Rune Halvorsen

• Økland, Inghild Halvorsen; Halvorsen, Rune; Nemes, Attila; Dawson, Lorna & Haraldsen, Trond (2026). Gradient analysis of relationships between soil, decomposition of human remains, and external factors in graves in four Norwegian municipalities. Urban Ecosystems. ISSN 1083-8155. 29(5). doi: 10.1007/s11252-026-02100-6. Fulltekst i vitenarkiv
• Naas, Adam Eindride; Horvath, Peter; Halvorsen, Rune; Sivertsen, Bendik & Bryn, Anders (2026). The impact of reference data errors on land-cover classifiers. Norsk Geografisk Tidsskrift. ISSN 0029-1951. doi: 10.1080/00291951.2026.2661590. Fulltekst i vitenarkiv Vis sammendrag

  Errors in thematically detailed land-cover maps have large consequences for downstream applications. Moreover, simulation-based studies suggest that land-cover classifiers are sensitive to errors in reference data. We (1) quantified the expected error from field interpretation of land-cover types; (2) the sensitivity of classifiers to reference data errors; and (3) the error transferred from reference data to classifiers. Lastly, we (4) recommended strategies to reduce errors. The study area was mapped by 12 field interpreters divided into three equal-sized experience-level groups. The field-based land-cover maps were aggregated to three thematic resolutions and used to train 6804 land-cover classifiers by varying inputs, algorithm, and hyperparameter values. Separately from the first field campaign, four field interpreters classified validation data points, which were used to quantify error for each field interpreter and land-cover classifier, as the proportion of incorrectly classified validation points. We observed (1) generally high and varying levels of interpreter error; (2) a strong relationship between interpreter and classifier error; and (3) a net positive transfer of errors from reference data to classifiers. Because classifier error seems largely driven by interpreter error at the levels commonly observed in thematically detailed land-cover mapping, we (4) recommend strategies to reduce interpreter error before modelling.

• Asplund, Ulrika Jansson; Karlsen, Damian Petkovic; Brysting, Anne Krag; Halvorsen, Rune; Kauserud, Håvard & Kjønaas, Janne [Vis alle 7 forfattere av denne artikkelen] (2026). Long-term effects of clear-cutting on understory plant communities in boreal forests. Forest Ecology and Management. ISSN 0378-1127. 613. doi: 10.1016/j.foreco.2026.123784. Fulltekst i vitenarkiv Vis sammendrag

  After five centuries of selective cutting in the boreal Fennoscandian forest there was a shift to stand replacing harvest (clear-cutting) in the 1940s. This shift altered light conditions experienced by the forest understory profoundly, from semi-open conditions to light regimes altering between very open in the recently clear-cut forest to very dense some decades later. In this study, we investigated the long-term effects of clear-cutting on vascular plants and bryophytes. Our study system consists of twelve pairs of mesic spruce forests in Southeastern Norway, with a previously clear-cut, but now mature stand and a near-natural forest within each pair. Vascular plant cover was almost twice as high in the near-natural than in the mature, previously clear-cut forest sites, despite similar standing volume and light availability. Overall, previous clear-cutting did not have long-term effects on species richness, but vascular plant species richness was more responsive to soil Ca, a key driver of plant community composition, in the near natural forests. Likewise, the community composition showed a stronger association with soil chemistry in near-natural forests, suggesting that management alters natural drivers of understory communities. The long-lasting effects of clear-cutting was distinct for understory cover and mainly driven by common species such as the keystone species Vaccinium myrtillus, which was substantially less abundant in previously clear-cut stands.

• Schuuring, Sil; Halvorsen, Rune; Eidesen, Pernille Bronken; Niittynen, Pekka; Kemppinen, Julia & Lang, Simone I. (2026). High Arctic vegetation lowers soil temperatures on sunny days despite low stature. Arctic, Antarctic and Alpine research. ISSN 1523-0430. 58(1). doi: 10.1080/15230430.2026.2649436. Fulltekst i vitenarkiv Vis sammendrag

  The impact of vegetation on soil temperatures in low Arctic and boreal regions is well documented,where dense vegetation reduces soil temperatures. However, equivalent empirical evidence forinfluence of sparse, low-stature high Arctic vegetation and its interaction with cloud cover islimited. Improved understanding of this relationship is vital, because soil temperatures driveimportant ecosystem processes, such as nutrient cycling and carbon fluxes. We investigatedwhether effects on soil temperature are found under smaller high Arctic vegetation in Svalbard,Norway, by modeling soil temperatures in relation to vegetation cover and height across forty plots,using July temperature recordings from 2020 to 2023. We found reduced minimum temperaturesunder thicker moss layers and taller forb and shrub vegetation, whereas organic layers reducedmaximum temperatures. These effects were strongest under sunny conditions, whereas shrubcover showed weak interactions with cloud cover. This contrasts with lower latitudes, where shrubsexert strong shading effects and vegetation reduces maximum and raises minimum soil tempera-tures. This discrepancy might stem from smaller diurnal temperature fluctuations, lower vegetationheight, and lower solar radiation in the high Arctic. Our results indicate that predicted vegetationshifts resulting from climate change may lead to complex soil temperature responses in the future.

• Ronold, Eivind Kverme; Morgado, Luis; Mundra, Sunil; Nybakken, Line; Halvorsen, Rune & Kauserud, Håvard (2026). Above- and belowground communities in boreal forests are tightly linked along common ecological gradients. Plant and Soil. ISSN 0032-079X. doi: 10.1007/s11104-026-08440-8. Fulltekst i vitenarkiv Vis sammendrag

  Aims Fungal communities in boreal forest soils are highly diverse, both taxonomically and functionally, with the majority of fungi associated with living or dead plants as saprotrophs, pathogens or mycorrhizal symbionts. The aim of this study was to examine to what extent soil fungal communities are structured by the above-ground vegetation versus topographic and edaphic factors. Methods We take advantage of a vegetation survey in which plant communities have been monitored in plots located along topographic and edaphic gradients in a boreal forest area in southern Norway, spanning from mesic spruce forests to xeric pine forests. To survey the corresponding fungal communities, we applied DNA metabarcoding of soil samples collected from the same permanent plots. Results The fungal soil communities exhibited a strong structure along the same edaphic and topographic gradients as the vegetation. Plant community composition explained most of the variation in fungal community composition followed by edaphic factors and topography. The xeric pine forest was characterized by high CN ratios, ericoid vegetation, and a correspondingly higher abundance of Ascomycota, many of which form ericoid mycorrhizae or are root-associated. The submesic spruce forest was characterized by higher pH, lower CN ratios, diverse understory vegetation and high abundance of ectomycorrhizal and white-rot litter decomposer Basidiomycota. Conclusions The gradient from mesic spruce- to xeric pine-dominated forest is ubiquitous in boreal forests, and we here show a strong link between composition of vegetation and fungal communities, highlighting long-term effects influencing both plant and fungal communities in similar and predictable ways.

• Naas, Adam Eindride; Simensen, Trond; Keetz, Lasse Torben; Tjessem, Ingrid Vesterdal; Bryn, Anders & Halvorsen, Rune [Vis alle 13 forfattere av denne artikkelen] (2026). Supporting spatial planning with high-spatial-resolution model-based ecosystem maps. Environmental impact assessment review. ISSN 0195-9255. 120. doi: 10.1016/j.eiar.2026.108433. Fulltekst i vitenarkiv Vis sammendrag

  Field-based ecosystem maps are often used to support environmental impact assessments (EIAs) in later stages of spatial planning. During the early stages, however, information on geographical distributions of ecosystems is typically unavailable. This can result in uninformed decisions, with negative consequences for biodiversity and ecosystem services. Although model-based maps offer low-cost wall-to-wall coverage, they are rarely used for spatial planning. Using Norway as a study system, we aimed to: (1) quantify the coverage of field-based ecosystem maps in areas reserved for development; (2) use a model-based map to assess ecosystem extents in these areas; and (3) provide guidance on how model-based maps can support spatial planning. We first collated municipality-level land-use plans and intersected these with existing field-based ecosystem maps created for EIAs. Then, we constructed a model-based map for 17 ecosystem types with a 10 m × 10 m resolution that was intersected with the unsurveyed land-use plans. We estimated that 4.2 km2 of land is reserved for development in an average municipality, of which 0.3 km2 is covered by field-based maps. Our model-based map indicates, with moderate uncertainty, that 260 km2 covered by red-listed ecosystem types is at risk of being affected if unsurveyed land reserves are developed. However, improvements in model training and uncertainty quantification methodology should be considered to increase utility of the maps. We provide guidelines for using model-based ecosystem maps in spatial planning, especially in early planning stages, aiming to support decision-making while taking the limitations of model-based maps into account.

• Simensen, Trond; Bryn, Anders; Chipperfield, Joseph; Halvorsen, Rune; Naas, Adam Eindride & Töpper, Joachim Paul [Vis alle 8 forfattere av denne artikkelen] (2026). Bruk av utbredelsesmodeller for arter og naturtyper i arealplanlegging og naturforvaltning. Kart og Plan. ISSN 0047-3278. 119(1), s. 18–35. doi: 10.18261/kp.119.1.3. Fulltekst i vitenarkiv Vis sammendrag

  For å ivareta naturhensyn i arealplanlegging trenger vi kunnskap om hvor arter og naturtyper finnes, om bestandsstørrelser og om økologisk tilstand. Kart over registrerte forekomster er nyttige, men ofte ufullstendige. Utbredelsesmodeller kan supplere dagens arts- og naturtypekart ved å predikere sannsynlig forekomst i hele landskapet basert på kjente funn og miljødata. Slike modeller brukes mye i økologi, men sjeldnere i arealplanlegging. Dette skyldes delvis mangel på relevante modellerte kart av god nok kvalitet, delvis at modeller kan være krevende å tolke, og delvis skepsis mot bruk av modellerte data. I denne artikkelen gir vi en kort, ikke-teknisk innføring i utviklingen innen utbredelsesmodellering, viser eksempler på ulike typer utbredelsesmodeller, og foreslår en sjekkliste til støtte for bestilling, tolkning og ansvarlig bruk av utbredelsesmodeller i planlegging og naturforvaltning.

• Vloon, Catharina Caspara; Halvorsen, Rune; Nordbakken, Jørn-Frode; Töpper, Joachim Paul; Auestad, Inger & Rydgren, Knut (2025). Vegetation Dynamics on a Boreal Raised Bog: Changes in Carpets, Lawns and Hummocks Towards Wetter Conditions Over a 34‐Year Period. Journal of Vegetation Science (JVS). ISSN 1100-9233. 36(6). doi: 10.1111/jvs.70095. Fulltekst i vitenarkiv Vis sammendrag

  Question How do vascular plant and cryptogam cover, bare peat area and species composition in different microforms on a boreal raised bog change over a 34-year period (1988–2022)? We discuss the observed patterns in the light of ongoing climate change. Location Rønnåsmyra Nature Reserve, south-eastern Norway. Methods We recorded total vascular plant and cryptogam cover, bare peat area and species composition in 51 permanent 0.5 × 0.5 m plots in 1988, 2004 and 2022. The plots were assigned to microform classes (carpet, lawn, hummock) based on their characteristics in 1988 and 2022. We analysed changes over time and explored the relationship between change in species composition and change in the relative distance from the bog surface to the groundwater table (rDWT) in each microform using linear mixed-effect models and ordination (GNMDS). Results No shifts between microforms had occurred during the 34-year period, but the number of observed taxa had decreased from 51 to 38. While the vegetation changed very little between 1988 and 2004, substantial changes occurred from 2004 to 2022. During this period, carpets showed a substantial increase in bare peat at the cost of cryptogam and vascular plant cover. Lawns showed a similar but less strong trend. Hummocks showed no such changes. The species composition of all microforms changed towards vegetation typical of wetter bog surfaces. In hummocks, this implied a shift from dominance by lichens to dominance by strongly peat-producing Sphagnum species of section Acutifolia, coupled with an increase in rDWT. Conclusion We demonstrate that bog vegetation can change substantially within two decades. The observed, divergent successions—retrogressive in carpets and lawns and progressive in hummocks—may result from the responses of the cryptogam layer to a combination of increased temperature and increased precipitation. Extreme weather events may have contributed to the increase in bare peat.

• Rydgren, Knut; Andersen, Roxane; Halvorsen, Rune; Hancock, Mark H.; Hughes, Robert D. & Martin-Walker, Alice [Vis alle 8 forfattere av denne artikkelen] (2025). Restoration of formerly afforested blanket bog: Estimating time for vegetation recovery. Ecological Applications. ISSN 1051-0761. 35(8). doi: 10.1002/eap.70138. Fulltekst i vitenarkiv Vis sammendrag

  Peatland restoration aims to restore hydrology and peat-forming vegetation, supporting other ecosystem functions. However, the time required for complete vegetation recovery is generally unknown. Here, we investigate this in an experimentally restored, formerly afforested blanket bog in northern Scotland, which was plowed, fertilized, and planted with non-native conifers in the mid-1980s. Plowing created three “microforms”: Ridges, Original surface, and Furrows. Restoration management took place in two stages: trees were felled and drains blocked in 1998 (Standard treatment); then parts of the area were further rewetted with additional drain-blocking in 2015/2016 (Enhanced treatment). We recorded plant species composition in permanent quadrats 0, 5, 13, and 24 years after the start of restoration. Here we use an ordinationregression-based approach (ORBA) to predict time to plant species compositional recovery compared with a reference (comparable nearby intact blanket bog). For the first 13 years, plant species composition diverged from the reference, then later started to converge. If the current speed and direction of vegetation change were maintained, predicted time to recovery varies between 50–100 years and 120–285 years applying a relaxed or strict criterion for restoration success, respectively. Seven growing seasons after Enhanced treatment, recovery speed increased only for the driest microform, Ridge. Surprisingly, this microform was not predicted to take longer to recover than other microforms under either treatment. On the landscape scale, sloping areas were harder to restore than flatter areas, having longer predicted times to recovery. Complete vegetation restoration may take a long time because of legacies from the afforestation (e.g., increased nutrient availability) and the time taken to fully restore surface morphology and water table. On the other hand, other research has already demonstrated that the site is currently acting as a net carbon sink, despite the incomplete vegetation recovery. We argue that functions may be restored without full recovery of species composition. However, approaching the full suite of species may be desirable to support long-term resilience. Successful peatland restoration needs a strong science-practice partnership, where learning gained from monitoring both damaged and comparable intact peatlands can be used to adapt management interventions.

• Lunde, Lisa Fagerli; Birkemoe, Tone; Sverdrup-Thygeson, Anne; Asplund, Johan; Halvorsen, Rune & Kjønaas, O. Janne [Vis alle 11 forfattere av denne artikkelen] (2025). Towards repeated clear-cutting of boreal forests – a tipping point for biodiversity? Biological Reviews. ISSN 1464-7931. 100(3), s. 1181–1205. doi: 10.1111/brv.13180. Fulltekst i vitenarkiv Vis sammendrag

  Boreal forests are important carbon sinks and host a diverse array of species that provide important ecosystem functions. Boreal forests have a long history of intensive forestry, in which even-aged management with clear-cutting has been the dominant harvesting practice for the past 50–80 years. As a second cycle of clear-cutting is emerging, there is an urgent need to examine the effects of repeated clear-cutting events on biodiversity. Clear-cutting has led to reduced numbers of old and large trees, decreased volumes of dead wood of varied decay stages and diameters, and altered physical and chemical compositions of soils. The old-growth boreal forest has been fragmented and considerably reduced. Here, we review short- and long-term (≥50 years) effects of clear-cutting on boreal forest biodiversity in four key substrates: living trees, dead wood, ground and soil. We then assess landscape-level changes (habitat fragmentation and edge effects) on this biodiversity. There is evidence for long-term community changes after clear-cutting for several taxa: epiphytic lichens; saproxylic fungi, bryophytes and insects; epigeic bryophytes; and soil snails, bacteria, and ectomycorrhizal fungi. Long-term declines in species richness were found for saproxylic fungi, bryophytes and true flies. However, for the majority of taxa, long-term effects of clear-cutting are not well understood. On the landscape level, reduced connectivity to old-growth forests has negative effects on several species of fungi, lichens, bryophytes and insects, notably among Red-Listed species. Furthermore, altered microclimate near clear-cut edges negatively affects epiphytic lichens and epigeic arthropods, implying complex effects of habitat fragmentation. Repeated cycles of clear-cutting might pose even stronger pressures on boreal forest biodiversity due to continued fragmentation of old-growth forests and accumulation of extinction debts. Examining the broad effects of forestry on biodiversity across the boreal biome is crucial: (i) to increase our knowledge of long-term and landscape-level effects of former clear-cutting; and (ii) to gain a better understanding of how forestry will affect biodiversity and, subsequently, ecosystem functioning, with repeated cycles of clear-cutting.

• Sulavik, Jan; Auestad, Inger; Boudreau, Stéphane; Halvorsen, Rune & Rydgren, Knut (2024). Population re-establishment and spatial dynamics of crowberry (Empetrum nigrum ssp. hermaphroditum), a foundation species in restored alpine ecosystems. Ecology and Evolution. 14(9). doi: 10.1002/ece3.70242. Fulltekst i vitenarkiv Vis sammendrag

  Many ecosystems are defined and shaped by one or a few common, foundation species. Even though such species hold a key role in the restoration of these ecosystems, the demographic processes involved in their re-establishment have rarely been studied. Foundation species' population dynamics, re-establishment history, and the abiotic and biotic factors that affect individual establishment at restored sites can be studied by addressing population spatial patterns and age structure. Such an approach to studying population dynamics is particularly relevant for long-lived species with low mortality, such as shrubs in alpine areas. We studied a population of the foundation species Empetrum nigrum ssp. hermaphroditum at an alpine spoil heap site and found evidence of population re-establishment starting within a decade after construction. High Empetrum densities close to the spoil heap edges indicated that short distances to seed sources in the surroundings had a strong positive effect on establishment of individuals. Empetrum individuals were significantly clustered, which indicated intraspecific facilitation. As revealed by spatial analyses of recruits and older, established individuals, clustering developed gradually over time, which indicated a shift from no interaction to increased facilitation. We conclude that intraspecific facilitation promotes Empetrum reestablishment at the studied alpine spoil heap. Synthesis: We show that population spatial patterns and age structure can be successfully used to unveil the re-establishment history of a foundation species in a restoration context. Efficient seed dispersal and intraspecific facilitation seem to be important factors behind Empetrum's successful re-establishment at alpine spoil heaps. Identification of abiotic and biotic factors determining foundation species' establishment success at restored sites can support planning and improve success of restoration.

• Salazar, Maria Ariza; Engelstad, Mari; Lieungh, Eva; Laux, Marcele; Ready, Jonathan & Mauvisseau, Quentin [Vis alle 8 forfattere av denne artikkelen] (2024). Evaluating the feasibility of using plant-specific metabarcoding to assess forest types from soil eDNA. Applied Vegetation Science. ISSN 1402-2001. 27(4). doi: 10.1111/avsc.12806. Fulltekst i vitenarkiv Vis sammendrag

  Questions An essential aspect of variation in natural systems is that species respond to complex environmental gradients. Recognizing plant composition gradients associated with abiotic factors (ecoclines) can be foundational for defining habitat types, which, in turn, helps map natural variation. Typically, ecoclinal structures are assessed through visual evaluation of above-ground vegetation and analysis of covarying abiotic factors. However, the correlation between ecological structures detected by soil eDNA plant assessments and those identified by visual assessment remains largely unexplored. Location Hvaler archipelago, southern Norway. Methods Plant diversity assessments were conducted using metabarcoding of the trnL (UUA) intron p6 loop and ITS2 from 31 soil samples collected across six forest types. These forest types span gradients related to drought risk and calcium richness. Results The barcode amplicons identified 70 plant taxa, primarily vascular plants (67), with most assigned to the species level (59), representing common forest taxa across the sites. Comparisons between soil eDNA compositions and theoretical forest-type compositions showed a low to medium correspondence (26% to 76%) between the two. Ordinations of soil eDNA compositions revealed two axes without clear ecological interpretation and correlated poorly with the calcium–richness gradient previously identified by visual assessments. Conclusions Overall, our results emphasize the necessity for comprehensive sequence reference libraries to conduct thorough plant biodiversity assessments. They also highlight the potential of soil eDNA to assess plant composition, which can aid in ecosystem mapping.

• Handegard, Eivind; Gjerde, Ivar; Halvorsen, Rune; Lewis, Robert John; Storaunet, Ken Olaf & Sætersdal, Magne [Vis alle 7 forfattere av denne artikkelen] (2024). How important is Forest Age in explaining the species composition of Near-natural Spruce Forests? Forest Ecology and Management. ISSN 0378-1127. 569. doi: 10.1016/j.foreco.2024.122170. Fulltekst i vitenarkiv Vis sammendrag

  Multiple ecological drivers, along with forest age, determine the species composition of boreal forest ecosystems. However, the role of age in successional changes in forests cannot be understood without taking site conditions, the disturbance regime and forest structure into account. In this study, we ask two research questions: 1. What is the relationship between forest age and overall species composition in older near-natural spruce forests, i.e. forests of age beyond harvest maturity? 2. Do species associated with different forest habitats respond similarly to variation in forest age? Data were collected in 257 Norway spruce dominated 0.25 ha plots from three study areas in Southeastern and Central Norway. Species inventories were conducted for lichens and bryophytes on trees and rocks, vascular plants on the forest floor, and for deadwood-associated bryophytes and polypore fungi. Although NMDS ordination analyses of the total species composition identified a main axis related to the age of the oldest trees in two of the study areas, variation partitioning analyses showed that age explained a small fraction of variation of the species composition compared to site conditions, logging history, forest structure, and differences between the sites in all habitats. The unique variation explained by forest age species was, however, significant for all habitats. The fraction of variation in species composition explained by forest age was the largest for lichens and bryophytes on trees, and for deadwood-associated bryophytes and polypore fungi. Our results suggest that practical mapping of near-natural forests for management purposes inventories should include site conditions, forest structure and between site differences in addition to forest age.

• Schuuring, Sil; Halvorsen, Rune; Eidesen, Pernille Bronken; Niittynen, Pekka; Kemppinen, Julia & Lang, Simone Iris (2024). High Arctic Vegetation Communities With a Thick Moss Layer Slow Active Layer Thaw. Journal of Geophysical Research (JGR): Biogeosciences. ISSN 2169-8953. 129(8). doi: 10.1029/2023JG007880. Fulltekst i vitenarkiv Vis sammendrag

  Svalbards permafrost is thawing as a direct consequence of climate change. In the Low Arctic, vegetation has been shown to slow down and reduce the active layer thaw, yet it is unknown whether this also applies to High Arctic regions like Svalbard where vegetation is smaller, sparser, and thus likely less able to insulate the soil. Therefore, it remains unknown which components of High Arctic vegetation impact active layer thaw and at which temporal scale this insulation could be effective. Such knowledge is necessary to predict and understand future changes in active layer in a changing Arctic. In this study we used frost tubes placed in study grids located in Svalbard with known vegetation composition, to monitor the progression of active layer thaw and analyze the relationship between vegetation composition, vegetation structure and snow conditions, and active layer thaw early in summer. We found that moss thickness, shrub and forb height, and vascular vegetation cover delayed soil thaw immediately after snow melt. These insulating effects attenuated as thaw progressed, until no effect on thaw depth was present after 8 weeks. High Arctic mosses are expected to decline due to climate change, which could lead to a loss in insulating capacity, potentially accelerating early summer active layer thaw. This may have important repercussions for a wide range of ecosystem functions such as plant phenology and decomposition processes.

• Naas, Adam Eindride; Keetz, Lasse Torben; Halvorsen, Rune; Horvath, Peter; Mienna, Ida Marielle & Simensen, Trond [Vis alle 7 forfattere av denne artikkelen] (2024). Choice of predictors and complexity for ecosystem distribution models: effects on performance and transferability. Ecography. ISSN 0906-7590. 2024(8). doi: 10.1111/ecog.07269. Fulltekst i vitenarkiv Vis sammendrag

  There is an increasing need for ecosystem-level distribution models (EDMs) and a better understanding of which factors affect their quality. We investigated how the performance and transferability of EDMs are influenced by 1) the choice of predictors and 2) model complexity. We modelled the distribution of 15 pre-classified ecosystem types in Norway using 252 predictors gridded to 100 × 100 m resolution. The ecosystem types are major types in the ‘Nature in Norway' system mainly defined by rule-based criteria such as whether soil or specific functional groups (e.g. trees) are present. The predictors were categorised into four groups, of which three represented proxies for natural, anthropogenic, or terrain processes (‘ecological predictors') and one represented spectral and structural characteristics of the surface observable from above (‘surface predictors'). Models were generated for five levels of model complexity. Model performance and transferability were evaluated with data collected independently of th

• Ransedokken, Yngvild Eidissen; Asplund, Johan; Morgado, Luis; Kauserud, Håvard; Mundra, Sunil & Ohlson, Mikael [Vis alle 8 forfattere av denne artikkelen] (2024). Synchronic shifts in phenolic compounds and fungal communities during litter decomposition in boreal forests. Forest Ecology and Management. ISSN 0378-1127. 554. doi: 10.1016/j.foreco.2024.121696. Fulltekst i vitenarkiv Vis sammendrag

  Phenolic compounds in plant litter influence decomposition process both directly by their own degree of decomposability and indirectly by affecting decomposer processes. While phenolic characteristics of aboveground plant biomass are well-known, the fate of litter phenolics and their regulatory effects on belowground decomposition remain unclear. We conducted a two-year decomposition experiment distributing litterbags of spruce, pine, and bilberry along a gradient from mesic spruce-dominated to xeric pine-dominated forests. Litter material was analysed for mass loss, low molecular weight phenolic compounds, condensed tannins, fungal biomass, and fungal community composition (using DNA metabarcoding). Bilberry litter initially decayed more rapidly than the conifer litter, but the remaining mass of bilberry litter was the same as for pine and higher than that of spruce litter after two years. The concentration and composition of phenolic compounds decreased with time, with mainly MeOH-insoluble condensed tannins remaining at the end of the experiment. Correspondingly, fungal biomass increased in the first year, while all litter types underwent rapid changes in fungal community composition. The species-specific pattern of temporal change in mass loss, as well as in the synchronic shift in composition of phenolic compounds and fungal community, give new insights in the importance of litter quality for the decomposition process.

• Naas, Adam Eindride; Halvorsen, Rune; Horvath, Peter; Wollan, Anders Kvalvåg; Bratli, Harald & Brynildsrud, Katrine Marie [Vis alle 16 forfattere av denne artikkelen] (2023). What explains inconsistencies in field-based ecosystem mapping? Applied Vegetation Science. ISSN 1402-2001. 26(1). doi: 10.1111/avsc.12715. Fulltekst i vitenarkiv Vis sammendrag

  Questions Field-based ecosystem mapping is prone to observer bias, typically resulting in a mismatch between maps made by different mappers, that is, inconsistency. Experimental studies testing the influence of site, mapping scale, and differences in experience level on inconsistency in field-based ecosystem mapping are lacking. Here, we study how inconsistencies in field-based ecosystem maps depend on these factors. Location Iškoras and Guollemuorsuolu, northeastern Norway, and Landsvik and Lygra, western Norway. Methods In a balanced experiment, four sites were field-mapped wall-to-wall to scales 1:5000 and 1:20,000 by 12 mappers, representing three experience levels. Thematic inconsistency was calculated by overlay analysis of map pairs from the same site, mapped to the same scale. We tested for significant differences between sites, scales, and experience-level groups. Principal components analysis was used in an analysis of additional map inconsistencies and their relationships with site, scale and differences in experience level and time consumption were analysed with redundancy analysis. Results On average, thematic inconsistency was 51%. The most important predictor for thematic inconsistency, and for all map inconsistencies, was site. Scale and its interaction with site predicted map inconsistencies, but only the latter were important for thematic inconsistency. The only experience-level group that differed significantly from the mean thematic inconsistency was that of the most experienced mappers, with nine percentage points. Experience had no significant effect on map inconsistency as a whole. Conclusion Thematic inconsistency was high for all but the dominant thematic units, with potentially adverse consequences for mapping ecosystems that are fragmented or have low coverage. Interactions between site and mapping system properties are considered the main reasons why no relationships between scale and thematic inconsistency were observed. More controlled experiments are needed to quantify the effect of other factors on inconsistency in field-based mapping.

• Auestad, Inger; Rydgren, Knut; Halvorsen, Rune; Avdem, Ingrid Hofmo; Berge, Rannveig & Bollingberg, Ina Marie [Vis alle 7 forfattere av denne artikkelen] (2023). Use climatic space-for-time substitutions with care: Not only climate, but also local environment affect performance of the key forest species bilberry along elevation gradient. Ecology and Evolution. 13(8). doi: 10.1002/ece3.10401. Fulltekst i vitenarkiv Vis sammendrag

  An urgent aim of ecology is to understand how key species relate to climatic and environmental variation, to better predict their prospects under future climate change. The abundant dwarf shrub bilberry (Vaccinium myrtillus L.) has caught particular interest due to its uphill expansion into alpine areas. Species' performance under changing climate has been widely studied using the climatic space-for-time approach along elevation gradients, but potentially confounding, local environmental variables that vary along elevation gradients have rarely been considered. In this study, performed in 10 sites along an elevation gradient (200–875 m) in W Norway, we recorded species composition and bilberry performance, both vegetative (ramet size and cover) and reproductive (berry and seed production) properties, over one to 4 years. We disentangled effects of local environmental variables and between-year, climatic variation (precipitation and temperature), and identified shared and unique contributions of these variables by variation partitioning. We found bilberry ramet size, cover and berry production to peak at intermediate elevations, whereas seed production increased upwards. The peaks were less pronounced in extreme (dry or cold) summers than in normal summers. Local environmental variables explained much variation in ramet size and cover, less in berry production, and showed no relation to seed production. Climatic variables explained more of the variation in berry and seed production than in ramet size and cover, with temperature relating to vegetative performance, and precipitation to reproductive performance. Bilberry's clonal growth and effective reproduction probably explain why the species persists in the forest and at the same time invades alpine areas. Our findings raise concerns of the appropriateness of the climatic space-for-time approach. We recommend including both climatic and local environmental variables in studies of variation along elevation gradients and conclude that variation partitioning can be a useful supplement to other methods for analysing variation in plant performance.

• Bendiksby, Mika; Thorbek, Birgitte Lisbeth Graae; Bjorå, Charlotte Sletten & Halvorsen, Rune (2023). Improving procedures for obtaining Sanger sequences from old herbarium specimens. Bauhinia. ISSN 0067-4605. doi: 10.12685/bauhinia.1352. Fulltekst i vitenarkiv Vis sammendrag

  Because DNA degrades over time, extracting DNA of sufficient quality for sequencing is presumed to be more difficult from older than younger herbarium specimens. Although massive parallel sequencing techniques have clear advantages when it comes to sequencing ancient DNA, Sanger sequencing is still in frequent use, prompting us to test and improve its application on herbarium specimens. During molecular phylogenetic investigations of the subfamily Lamioideae (Lamiaceae) and subgroups, we extracted DNA from 651 herbarium specimens collected between 1826 and 2006 using regular mini-prep methods. The aim was to obtain DNA of sufficient quality for Sanger sequencing of various plastid and nuclear genetic markers. Here, we report successful Sanger sequencing of the commonly used plastid marker, rps16, as a conservative measure of DNA quality, and logistic regression to investigate the relationship between age of the material and DNA quality. Our result indicates that the upper age limit for obtaining DNA suitable for Sanger sequencing from herbarium specimens using regular mini-prep DNA extraction methods has not been reached. After simple modifications to the regular DNA mini-prep and PCR procedures, at least one genetic marker was successfully sequenced for about 90 % of the specimens tested, the oldest being 168 years old. Jointly, despite the technique's drawbacks, these results demonstrate a high success rate of Sanger sequencing of herbarium specimens.

• Økland, Tonje; Halvorsen, Rune; Lange, Holger; Nordbakken, Jørn-Frode & Clarke, Nicholas (2023). Climate change drives substantial decline of understorey species richness and abundance in Norway spruce forests during 32 years of vegetation monitoring. Journal of Vegetation Science (JVS). ISSN 1100-9233. 34(3). doi: 10.1111/jvs.13191. Fulltekst i vitenarkiv Vis sammendrag

  Questions Observations in permanent forest vegetation plots in Norway and elsewhere indicate that complex changes have taken place over the period 1988–2020. These observations are summarised in the “climate-induced understorey change (CIUC)” hypothesis, i.e. that the understorey vegetation of old-growth boreal forests in Norway undergoes significant long-term changes and that these changes are consistent with the ongoing climate change as an important driver. Seven testable predictions were derived from the CIUC hypothesis. Location Norway. Methods Vegetation has been monitored in a total of 458 permanently marked plots, each 1 m2, in nine old-growth forest sites dominated by Picea abies at intervals of 5–8 years over the 32-year study period. For each of the 52 combinations of site and year, we obtained response variables for the abundance of single species, abundance and species density of taxonomic–ecological species groups and two size classes of cryptogams, and site species richness. All of these variables were subjected to linear regression modelling with site and year as predictors. Results Mean annual temperature, growing-season length and the number of days with precipitation were higher in the study period than in the preceding ca. 30-year period, resulting in increasingly favourable conditions for bryophyte growth. Site species richness decreased by 13% over the 32-year study period. On average, group abundance of vascular plants decreased by 24% (decrease in forbs: 38%). Patterns of group abundance change differed among cryptogam groups: although peat-moss abundance increased by 39%, the abundance of mosses, hepatics and lichens decreased by 13%, 49% and 67%, respectively. Group abundance of small cryptogams decreased by 61%, whereas a 13% increase was found for large cryptogams. Of 61 single species tested for abundance change, a significant decrease was found for 43 species, whereas a significant increase was found only for 6 species. Conclusions The major patterns of change in species richness, group species density and group abundance observed over the 32-year study period accord with most predictions from the CIUC hypothesis and are interpreted as direct and indirect responses to climate change, partly mediated through changes in the population dynamics of microtine rodents. The more favourable climate for bryophyte growth explains the observed increase for a few large bryophyte species, whereas the decrease observed for small mosses and hepatics is interpreted as an indirect amensalistic effect, brought about by shading and burial in mats of larger species and accelerated by reduced fine-scale disturbance by microtine rodents. Indirect effects of a thicker moss mat most likely drive the vascular plant decline although long-term effects of tree-stand dynamics and former logging cannot be completely ruled out. Our results suggest that the ongoing climate change has extensive, cascading effects on boreal forest ecosystems. The importance of long time-series of permanent vegetation plots for detecting and understanding the effects of climate change on boreal forests is emphasised.

• Bässler, Claus; Heilmann-Clausen, Jacob; Andrew, Carrie; Boddy, Lynne; Büntgen, Ulf & Diez, Jeffrey [Vis alle 17 forfattere av denne artikkelen] (2022). European mushroom assemblages are phylogenetically structured by temperature. Ecography. ISSN 0906-7590. 11. doi: 10.1111/ecog.06206. Fulltekst i vitenarkiv Vis sammendrag

  Recent global warming affects species compositions at an unprecedented rate. To predict climate-induced changes in species assemblages, a better understanding of the link between species occurrence and climate is needed. Macrofungal fruit body assemblages are correlated with the thermal environment at the European scale. However, it is still unknown whether macrofungal communities are also phylogenetically structured by thermal environments. Thermal environments are characterized by annual temperature means but also by intra-annual temperature variability (hereafter termed temperature seasonality), which are both considered in this study. Here, we used distribution data of 2882 species based on fruit body records across Europe to address two main questions: 1) are mushroom assemblages at the extremes of the mean (warm and cold) and seasonal (high intra-annual variability, i.e. continental) climate gradient phylogenetically more similar than expected (phylogenetic alpha diversity); 2) are mushroom assemblages, that are subject to different mean and seasonal temperature conditions, composed of different lineages (phylogenetic beta diversity). Our phylogenetic alpha diversity analysis shows that mushroom assemblages are phylogenetically structured by warm and cold environments, indicating that phylogenetically related species with similar traits thrive under more extreme conditions. In contrast, assemblages are phylogenetically more dissimilar (overdispersed) in temperature seasonal environments, indicating limiting similarity. Phylogenetic beta diversity was significantly correlated with mean and seasonal temperature differences, a response mainly driven by a few genera. Our results show that macrofungal assemblages are phylogenetically structured by temperature across Europe, suggesting phylogenetically constrained specialization towards temperature extremes. Predicted anthropogenic warming is likely to affect species composition and phylogenetic diversity with additional consequences for the carbon- and nutrient cycles. assembly processes, climate change, fungal diversity, null models, regional

• Simensen, Trond; Halvorsen, Rune & Erikstad, Lars (2022). Gradient analysis of landscape variation in Norway. Sommerfeltia. ISSN 0800-6865. 40(1), s. 1–193. doi: 10.2478/som-2022-0001. Fulltekst i vitenarkiv Vis sammendrag

  Abstract A multitude of landscape characterisation and mapping methods exist, but few methods take into account that landscapes properties vary in a gradual, continuous manner along multiple directions of variation. In this study, we used gradient analytic methods, rooted in ecological continuum theory, to analyse landscape variation throughout Norway. The aim is to explain differences in landscape properties in the simplest possible way, by identifying ‘complex landscape gradients’ (CLGs), i.e. composite gradients of co-occurring landscape elements and properties. We collected data by stratified sampling of 100 test areas (20×20 km), in which we delineated a total of 3966 observation units (landscape polygons 4–30 km²) based on geo-morphological criteria. For each observation unit, 85 landscape variables were recorded. We identified patterns of variation in landscape element composition by parallel use of two multivariate statistical methods, detrended correspondence analysis (DCA) and global nonmetric multidimensional scaling (GNMDS). The analyses revealed that the most important properties explaining differences in total landscape elements composition was location of the landscape relative to the coastline and coarse-scale landform variation. Most landscape elements had distinct optima within specific segments along broad-scale complex-gradients in landscape properties. A tentative landscape-type hierarchy was built by an iterative procedure by which the amount of compositional turnover in landscape-element composition between adjacent types was standardised. Six ‘major landscape types’ were identified based on geomorphological criteria. Within each major type, we identified a unique set of 2–5 important CLGs, representing geo-ecological, bio-ecological, and land use-related landscape variation. Minor landscape types were obtained by combining segments along two or more CLGs. The study shows that geological diversity, biological diversity and human land-use are tightly intertwined at the landscape level of ecological complexity, and that predominantly abiotic processes control and constrain both biotic processes and human land use.

• Salazar, Maria Ariza; Fouks, Bertrand; Mauvisseau, Quentin; Halvorsen, Rune; Alsos, Inger Greve & Boer, Hugo de (2022). Plant biodiversity assessment through soil eDNA reflects temporal and local diversity. Methods in Ecology and Evolution. 14(2), s. 415–430. doi: 10.1111/2041-210X.13865. Fulltekst i vitenarkiv Vis sammendrag

  1. Several studies have shown the potential of eDNA-based proxies for plant identification, but little is known about their spatial and temporal resolution. This limits its use for plant biodiversity assessments and monitoring of vegetation responses to environmental changes. Here we calibrate the temporal and spatial plant signals detected with soil eDNA surveys by comparing with a standard visual above-ground vegetation survey.<p> <p>2. Our approach compares vegetation in an old-growth boreal forest in southern Norway, surveyed in 100 permanent 1-m2 plots seven times over a 30-year period, with a single soil eDNA metabarcoding-based survey from soil samples collected at the same 100 plots in the year of the last vegetation survey. <p>3. On average, 60% and 10% of the vascular plants and bryophytes recorded across all vegetation surveys were detected by soil eDNA. Taxa detected by soil eDNA were more representative for the local taxa pool than for the specific plot, and corresponded to those surveyed over the 30-year period although most closely matched the current taxa composition. Soil eDNA detected abundant taxa better than rare ones although both rare taxa and taxa unrecorded by the visual survey were detected. <p>4. Our study highlights the potential of soil eDNA assessments for monitoring of vegetation responses over broad spatial and temporal scales. The method's ability to detect abundant taxa makes it suitable for assessment of vegetation composition in a specific area and for broad-scale plant diversity assessments.

• Horvath, Peter; Tang, Hui; Halvorsen, Rune; Stordal, Frode; Tallaksen, Lena M. & Berntsen, Terje Koren [Vis alle 7 forfattere av denne artikkelen] (2021). Improving the representation of high-latitude vegetation distribution in dynamic global vegetation models. Biogeosciences. ISSN 1726-4170. 18(1), s. 95–112. doi: 10.5194/bg-18-95-2021. Fulltekst i vitenarkiv Vis sammendrag

  Vegetation is an important component in global ecosystems, affecting the physical, hydrological and biogeochemical properties of the land surface. Accordingly, the way vegetation is parameterized strongly influences predictions of future climate by Earth system models. To capture future spatial and temporal changes in vegetation cover and its feedbacks to the climate system, dynamic global vegetation models (DGVMs) are included as important components of land surface models. Variation in the predicted vegetation cover from DGVMs therefore has large impacts on modelled radiative and non-radiative properties, especially over high-latitude regions. DGVMs are mostly evaluated by remotely sensed products and less often by other vegetation products or by in situ field observations. In this study, we evaluate the performance of three methods for spatial representation of present-day vegetation cover with respect to prediction of plant functional type (PFT) profiles – one based upon distribution models (DMs), one that uses a remote sensing (RS) dataset and a DGVM (CLM4.5BGCDV; Community Land Model 4.5 Bio-Geo-Chemical cycles and Dynamical Vegetation). While DGVMs predict PFT profiles based on physiological and ecological processes, a DM relies on statistical correlations between a set of predictors and the modelled target, and the RS dataset is based on classification of spectral reflectance patterns of satellite images. PFT profiles obtained from an independently collected field-based vegetation dataset from Norway were used for the evaluation. We found that RS-based PFT profiles matched the reference dataset best, closely followed by DM, whereas predictions from DGVMs often deviated strongly from the reference. DGVM predictions overestimated the area covered by boreal needleleaf evergreen trees and bare ground at the expense of boreal broadleaf deciduous trees and shrubs. Based on environmental predictors identified by DM as important, three new environmental variables (e.g. minimum temperature in May, snow water equivalent in October and precipitation seasonality) were selected as the threshold for the establishment of these high-latitude PFTs. We performed a series of sensitivity experiments to investigate if these thresholds improve the performance of the DGVM method. Based on our results, we suggest implementation of one of these novel PFT-specific thresholds (i.e. precipitation seasonality) in the DGVM method. The results highlight the potential of using PFT-specific thresholds obtained by DM in development of DGVMs in broader regions. Also, we emphasize the potential of establishing DMs as a reliable method for providing PFT distributions for evaluation of DGVMs alongside RS.

• Tholstrup, Ditte Wiig; Halvorsen, Rune & Dahlgren, Johan P. (2021). Age matters: Demographic senescence in the moss Polytrichastrum formosum. Journal of Ecology. ISSN 0022-0477. 109(8), s. 3024–3030. doi: 10.1111/1365-2745.13717. Fulltekst i vitenarkiv Vis sammendrag

  1. It is known that many animal species senesce demographically, showing a decrease in survival and/or fertility with age. Although there is mounting evidence for and against senescence in various flowering plant species, the question of whether senescence also occurs in other plant taxa, such as mosses and other bryophytes, remains unanswered. 2. We used GAMMs (generalised additive mixed models) and GLMMs to assess the effects of age on survival, size and the monocarpic female ramets' sexual reproduction in Polytrichastrum formosum using demographic, ramet-level data collected over 25 years in Solhomfjell nature reserve, Norway. 3. Survival was found to be negatively correlated with ramet age, with 1-year survival decreasing from 83% in 1-year-old to 43% in 10-year-old plants. Stem growth was positively correlated with survival but accounting for it in our models did not change the relationship between age and survival qualitatively. Annual growth decreased during the first years of the ramets' life but then stabilised. Sexual reproduction in the monocarpic females peaked at ramet age 2–4 years but was observed at ages up to 13 years. The longest-living (non-reproducing) ramet died at age 14. 4. Synthesis. Our findings indicate that Polytrichastrum formosum ramets experience constant actuarial senescence, at least in terms of survival. This finding improves our understanding of age-dependent demography in mosses, as well as in plants in general. This new knowledge about moss demography may also aid in management decisions for threatened species, as it can improve the precision of predictions of population longevity.

• Horvath, Peter; Halvorsen, Rune; Simensen, Trond & Bryn, Anders (2021). A comparison of three ways to assemble wall-to-wall maps from distribution models of vegetation types. GIScience & Remote Sensing. ISSN 1548-1603. 58(8), s. 1458–1476. doi: 10.1080/15481603.2021.1996313. Fulltekst i vitenarkiv Vis sammendrag

  Distribution modeling methods are used to provide occurrence probability surfaces for modeled targets. While most often used for modeling species, distribution modeling methods can also be applied to vegetation types. However, surfaces provided by distribution modeling need to be transformed into classified wall-to-wall maps of vegetation types to be useful for practical purposes, such as nature management and environmental planning. The paper compares the performance of three methods for assembling predictions for multiple vegetation types, modeled individually, into a wall-to-wall map. The authors used grid-cell based probability surfaces from distribution models of 31 vegetation types to test the three assembly methods. The first, a probability-based method, selected for each grid cell the vegetation type with the highest predicted probability of occurrence in that cell. The second, a performance-based method, assigned the vegetation types, ordered from high to low model performance, to a fraction of the grid cells given by the vegetation type’s prevalence in the study area. The third, a prevalence-based method, differed from the performance-based method by assigning vegetation types in the order from low to high prevalence. Thus the assembly methods worked in two principally different ways: the probability-based method assigned vegetation types to grid cells in a cell-by-cell manner, and both the performance-based method and prevalence-based method assigned them in a type-by-type manner. All methods were evaluated by use of reference data collected in the field, more or less independently of the data used to parameterize the vegetation-type models. Quantity, allocation, and total disagreement, as well as proportional dissimilarity metrics, were used for evaluation of assembly methods. Overlay analysis showed 38.1% agreement between all three assembly methods. The probability-based method had the lowest total disagreement with, and proportional dissimilarity from, the reference datasets, but the differences between the three methods were small. The three assembly methods differed strongly with respect to the distribution of the total disagreement on its quantity and allocation components: the cell-by-cell assignment method strongly favored allocation disagreement and the type-by-type methods strongly favored quantity disagreement. The probability-based method best reproduced the general pattern of variation across the study area, but at the cost of many rare vegetation types, which were left out of the assembled map. By contrast, the prevalence-based and performance-based methods represented vegetation types in accordance with nationwide area statistics. The results show that maps of vegetation types with wall-to-wall coverage can be assembled from individual distribution models with a quality acceptable for indicative purposes, but all the three tested methods currently also have shortcomings. The results also indicate specific points in the methodology for map assembly that may be improved. area frame survey, assembly strategies, distribution modeling, spatial probabilities, vegetation mapping, vegetation types

• Bryn, Anders; Bekkby, Trine; Rinde, Eli; Gundersen, Hege & Halvorsen, Rune (2021). Reliability in Distribution Modeling—A Synthesis and Step-by-Step Guidelines for Improved Practice. Frontiers in Ecology and Evolution. 9. doi: 10.3389/fevo.2021.658713. Fulltekst i vitenarkiv Vis sammendrag

  Information about the distribution of a study object (e.g., species or habitat) is essential in face of increasing pressure from land or sea use, and climate change. Distribution models are instrumental for acquiring such information, but also encumbered by uncertainties caused by different sources of error, bias and inaccuracy that need to be dealt with. In this paper we identify the most common sources of uncertainties and link them to different phases in the modeling process. Our aim is to outline the implications of these uncertainties for the reliability of distribution models and to summarize the precautions needed to be taken. We performed a step-by-step assessment of errors, biases and inaccuracies related to the five main steps in a standard distribution modeling process: (1) ecological understanding, assumptions and problem formulation; (2) data collection and preparation; (3) choice of modeling method, model tuning and parameterization; (4) evaluation of models; and, finally, (5) implementation and use. Our synthesis highlights the need to consider the entire distribution modeling process when the reliability and applicability of the models are assessed. A key recommendation is to evaluate the model properly by use of a dataset that is collected independently of the training data. We support initiatives to establish international protocols and open geodatabases for distribution models.

• Simensen, Trond; Erikstad, Lars & Halvorsen, Rune (2021). Diversity and distribution of landscape types in Norway. Norsk Geografisk Tidsskrift. ISSN 0029-1951. s. 1–23. doi: 10.1080/00291951.2021.1892177. Fulltekst i vitenarkiv Vis sammendrag

  Norwegian landscapes are changing at an increasingly rapid rate and therefore systematically structured information about observable landscape variation is required for knowledge-based management of landscape diversity. The purpose of the article is to present the first version of a complete, area covering, evidence-based, landscape type map of Norway, simultaneously addressing geoecological, bioecological and land use related variations. The type system used for the mapping is supported by systematically structured empirical evidence. The results of the mapping procedure, including the geographical distribution and descriptive statistics (abundance and areal coverage), are presented for each of the nine identified major landscape types identified based on coarse-scale landform variation. Within six inland and coastal major types, a large number of minor landscape types are defined based on the composition of geoecological, bioecological, and land use related landscape properties. The results provide new insights into the geography of Norwegian marine, coastal and inland landscapes. The authors discuss potential errors, uncertainties and limitations of the landscape type maps, and address the potential value of the new tool for research, management and planning purposes. They conclude that the results of the study might contribute to knowledge-based spatial planning and management of the unique landscape diversity of Norway.landscape diversity, landscape mapping, landscape type, Norway

• Simensen, Trond; Horvath, Peter; Vollering, Julien; Erikstad, Lars; Halvorsen, Rune & Bryn, Anders (2020). Composite landscape predictors improve distribution models of ecosystem types. Diversity and Distributions: A Journal of Conservation Biogeography. ISSN 1366-9516. 26(8), s. 928–943. doi: 10.1111/ddi.13060. Fulltekst i vitenarkiv Vis sammendrag

  Aim: Distribution modelling is a useful approach to obtain knowledge about the spatial distribution of biodiversity, required for, for example, red-list assessments. While distribution modelling methods have been applied mostly to single species, modelling of communities and ecosystems (EDM; ecosystem-level distribution modelling) produces results that are more directly relevant for management and decision-making. Although the choice of predictors is a pivotal part of the modelling process, few studies have compared the suitability of different sets of predictors for EDM. In this study, we compare the performance of 50 single environmental variables with that of 11 composite landscape gradients (CLGs) for prediction of ecosystem types. The CLGs represent gradients in landscape element composition derived from multivariate analyses, for example “inner-outer coast” and “land use intensity.” Location: Norway. Methods: We used data from field-based ecosystem-type mapping of nine ecosystem types, and environmental variables with a resolution of 100 × 100 m. We built nine models for each ecosystem type with variables from different predictor sets. Logistic regression with forward selection of variables was used for EDM. Models were evaluated with independently collected data. Results: Most ecosystem types could be predicted reliably, although model performance differed among ecosystem types. We identified significant differences in predictive power and model parsimony across models built from different predictor sets. Climatic variables alone performed poorly, indicating that the current climate alone is not sufficient to predict the current distribution of ecosystems. Used alone, the CLGs resulted in parsimonious models with relatively high predictive power. Used together with other variables, they consistently improved the models. Main conclusions: Our study highlights the importance of variable selection in EDM. We argue that the use of composite variables as proxies for complex environmental gradients has the potential to improve predictions from EDMs and thus to inform conservation planning as well as improve the precision and credibility of red lists and global change assessments.conservation planning, distribution modelling, ecosystem classification, ecosystem types, IUCN Red List of Ecosystems, landscape gradients, spatial prediction, species response curves

• Auestad, Inger; Rydgren, Knut & Halvorsen, Rune (2020). Dataset properties affect the performance of the ordination regression-based approach (ORBA) in predicting time to recovery. Ecological Engineering: The Journal of Ecotechnology. ISSN 0925-8574. 152. doi: 10.1016/j.ecoleng.2020.105875. Fulltekst i vitenarkiv
• Sulavik, Jan; Auestad, Inger; Halvorsen, Rune & Rydgren, Knut (2020). Assessing recovery of alpine spoil heaps by vascular plant, bryophyte, and lichen functional traits. Restoration Ecology. ISSN 1061-2971. s. 1–12. doi: 10.1111/rec.13257. Fulltekst i vitenarkiv Vis sammendrag

  Functional traits are linked to ecosystem processes and services and therefore relevant in recovery assessment. However, traits of bryophytes and lichens, important components of many ecosystems, have received less attention than those of vascular plants. We explored the use of functional traits of multiple important organism groups in recovery assessment. We combined data on traits and species composition for vascular plants, bryophytes, and lichens from four alpine spoil heaps and their undisturbed surroundings in western Norway, collected at three time‐points spanning more than two decades. We studied changes in community‐weighted mean (CWM) trait values and distribution of trait‐category optima over time. We analyzed temporal variation in joint functional trait composition using the ordination regression‐based approach (ORBA) to predict time to recovery. We observed functional shifts along the successional gradient for all organism groups, e.g. from wind‐dispersed propagules shortly after disturbance to vegetative reproduction at later successional stages. Over time, the similarity between dispersal‐related traits of vascular plants and bryophytes on the spoil heaps and in their surroundings increased, indicating that propagule influx is important in alpine restoration. The joint functional trait composition of all spoil heaps converged towards that of their surroundings: one spoil heap had recovered 34 years after construction, while the predicted time to recovery for the other three was 59–74 years. Our results indicate that inclusion of multiple organism groups improves trait‐based recovery assessments and time‐to‐recovery predictions. Further development of trait databases is essential for future use of joint functional trait composition in recovery assessment.

• Jašková, Anni; Braslavskaya, Tatyana Yu.; Tikhonova, Elena; Paal, Jaanus; Rūsiņa, Solvita & Laiviņš, Māris [Vis alle 29 forfattere av denne artikkelen] (2020). European Boreal Forest Vegetation Database. Phytocoenologia. ISSN 0340-269X. 50(1), s. 79–92. doi: 10.1127/phyto/2019/0336. Fulltekst i vitenarkiv Vis sammendrag

  The European Boreal Forest Vegetation Database (EBFVD, GIVD ID: EU-00-027) is a repository for vegetation-plot data from the forests of the boreal and hemiboreal zones of Europe. In this report, we describe its structure, current content and future perspectives opened up by the database. In February 2019, the database contained 13 037 vegetation-plot records from Belarus, Estonia, Finland, Latvia, Norway, Russia and Sweden that are not yet stored in the databases of the European Vegetation Archive (EVA). Consequently, this database significantly improves the availability of forest plant community data from Northern Europe. The database is managed by the Vegetation Science Group, Department of Botany and Zoology, Masaryk University, Brno (Czech Republic), in the TURBOVEG 2 program. It is registered in the Global Index of Vegetation Plot Databases (GIVD) and included in EVA. The whole database, or a subset of it, can be requested via EVA, or directly from the database custodian.

• Halvorsen, Rune; Skarpaas, Olav; Bryn, Anders; Bratli, Harald; Erikstad, Lars & Simensen, Trond [Vis alle 7 forfattere av denne artikkelen] (2020). Towards a systematics of ecodiversity: the Ecosyst framework. Global Ecology and Biogeography. ISSN 1466-822X. 29(11), s. 1887–1906. doi: 10.1111/geb.13164. Fulltekst i vitenarkiv Vis sammendrag

  Background Although a standard taxonomy of organisms has existed for nearly 300 years, no consensus has yet been reached on principles for systematization of ecological diversity (i.e., the co‐ordinated variation of abiotic and biotic components of natural diversity). In a rapidly changing world, where nature is under constant pressure, standardized terms and methods for characterization of ecological diversity are urgently needed (e.g., to enhance precision and credibility of global change assessments). Aim The aim is to present the EcoSyst framework, a set of general principles and methods for systematization of natural diversity that simultaneously addresses biotic and abiotic variation, and to discuss perspectives opened by this framework. Innovation EcoSyst provides a framework for systematizing natural variation in a consistent manner across different levels of organization. At each ecodiversity level, EcoSyst principles can be used to establish: (a) an extensive attribute system with descriptive variables that cover all relevant sources of variation; (b) a hierarchical‐type system; and (c) a set of guidelines for land‐cover mapping that is consistent across spatial scales. EcoSyst type systems can be conceptualized as multidimensional models, by which a key characteristic (the response) is related to variation in one or more key sources of variation (predictors). EcoSyst type hierarchies are developed by a gradient‐based iterative procedure, by which the “ecodiversity distance” (i.e., the extent to which the key characteristic differs between adjacent candidate types) is standardized and the ecological processes behind observed patterns are explicitly taken into account. Application We present “Nature in Norway” (NiN), an implementation of the EcoSyst framework for Norway for the ecosystem and landscape levels of ecodiversity. Examples of applications to research and management are given. Conclusion The EcoSyst framework provides a theoretical platform, principles and methods that can complement and enhance initiatives towards a global‐scale systematics of ecodiversity. iodiversity complex gradient continuum theory ecodiversity ecosystem geodiversity gradient landscape mapping typology

• Økland, Tonje; Aarrestad, Per Arild; Bakkestuen, Vegar & Halvorsen, Rune (2019). Mengdeendringer for utvalgte plantearter 1988–2018. I Framstad, Erik (Red.), Terrestrisk naturovervåking i 2018: Markvegetasjon, epifytter, smågnagere og fugl. Sammenfatning av resultater. Norsk institutt for naturforskning (NINA). ISSN 9788242634429. s. 96–102. Fulltekst i vitenarkiv Vis sammendrag

  Program for terrestrisk naturovervåking startet i 1990 og omfatter undersøkelser av vanlige planter og dyr i seks områder i bjørkeskog og elleve i granskog. Her ses resultatene fra 2018 i sammenheng med resultatene fra tidligere år. Markvegetasjonen i bjørkeskog i Gutulia har siden 1993 endret seg fra fattige lyng- og bærlyng-dominerte typer til svakt rikere lågurttyper med større innslag av urter, gras og starr. Dette skyldes trolig at lengre og mildere vekstsesong på høsten har ført til noe mer baserikhet i jorda og økt næringstilgangen til plantene. I Dividalen har bregner og urter økt i mengde, mens blåbær, fjellplanter, moser og lav har avtatt. Endringene skyldes trolig mildere klima og økt næringstilgang. Markvegetasjonen i granskog i Paulen viste betydelig tilbakegang i antall registrerte arter av karplanter og moser pr. analyseflate, både fra begynnelsen av overvåkingen i 1990 og siden forrige registrering (2010). Totalt antall registrerte plantearter er også redusert, fra 87 i 1990 til 79 i 2018. Siden 1990 var det tilbakegang i mengde for ni karplantearter og ti mosearter; ingen arter økte i mengde. Artssammensetningen har blitt mer homogen, med større likhet mellom ‘fattig’ og ‘rik’ vegetasjon. I perioden 2013–18 viste markvegetasjonen i granskog i Solhomfjell redusert mengde for moderat mineralnæringskrevende arter i rikere granskog, som på slutten av 1900-tallet. Økningen i bunnsjiktsdekning stoppet opp, men store mosearter synes å ha nådd en mengde, og mosemattene en tetthet, som har gitt vedvarende reduksjon for små moser. Populasjonsundersøkelsene av etasjemose i sju granskogsområder bekrefter at populasjonsøkningen stagnerer i områder med høy bunnsjiktsdekning, men det er fortsatt tendens til at store moser som etasjemose øker noe i mengde på bekostning av små moser. Disse mønstrene antas å ha blitt forsterket av mangelen på toppår i smågnagerbestander, slik at mosemattene blir fortettet gjennom mangel på for-styrrelse. I furuskogen i Solhomfjell ble det funnet redusert artstetthet og redusert mengde for mange lavarter og andre arter med tyngdepunkt i den mer tørkeutsatte furuskogen. Både i Gutulia og Dividalen har mengden epifytter på bjørketrær økt over overvåkingsperioden, men økningen synes nå å ha stagnert. Generelt øker dominansen av svakt varmekjære arter. Andel skadd lav er betydelig redusert fra 1993, men varierer med klimaforholdene om vinteren. Endringene reflekterer mindre svovelnedfall og gunstig klimautvikling med lengre vekstsesong, økt temperatur og nedbør. Siden 2014 har det vært utbrudd av bjørkemålere i 2014 i Dividalen, 2018 i Børgefjell og 2017 i øvrige fjellområder. Det var betydelige beiteskader på bjørkeblader i 2017/2018 i alle områdene utenom Dividalen. Smågnagere viser nokså regelmessige bestandstopper i Møsvatn, Åmotsdalen og Børgefjell, men mer uregelmessige og lavere topper i øvrige TOV-områder (Lund, Solhomfjell, Gutulia, Dividalen). I 2018 var det stor bestand av smågnagere (særlig gråsidemus, rødmus og markmus) i Dividalen, men lav eller svært lav bestand i øvrige områder. Ungeproduksjonen for kongeørn lå i 2018 noe under gjennomsnittet for overvåkingsperioden i Børgefjell, Åmotsdalen, Møsvatn og Gutulia, omtrent som snittet i Solhomfjell og noe over i Lund. Produksjonen i 2018 var noe lavere enn i 2017 for alle områdene unntatt Lund. Ungeproduksjonen for jaktfalk var betydelig lavere i 2018 enn gjennomsnitt

• Krah, Franz-Sebastian; Büntgen, Ulf; Schaefer, Hanno; Müller, Jörg; Andrew, Carrie & Boddy, Lynne [Vis alle 25 forfattere av denne artikkelen] (2019). European mushroom assemblages are darker in cold climates. Nature Communications. 10:2890, s. 1–11. doi: 10.1038/s41467-019-10767-z. Fulltekst i vitenarkiv Vis sammendrag

  Thermal melanism theory states that dark-colored ectotherm organisms are at an advantage at low temperature due to increased warming. This theory is generally supported for ectotherm animals, however, the function of colors in the fungal kingdom is largely unknown. Here, we test whether the color lightness of mushroom assemblages is related to climate using a dataset of 3.2 million observations of 3,054 species across Europe. Consistent with the thermal melanism theory, mushroom assemblages are significantly darker in areas with cold climates. We further show differences in color phenotype between fungal lifestyles and a lifestyle differentiated response to seasonality. These results indicate a more complex ecological role of mushroom colors and suggest functions beyond thermal adaption. Because fungi play a crucial role in terrestrial carbon and nutrient cycles, understanding the links between the thermal environment, functional coloration and species’ geographical distributions will be critical in predicting ecosystem responses to global warming.

• Olsen, Siri Lie; Brandrud, Tor Erik & Halvorsen, Rune (2019). Tilbakegang for flueblom Ophrys insectifera i Røsskleiva naturreservat i perioden 1984-2017. Blyttia : Norsk botanisk forenings tidsskrift. ISSN 0006-5269. 77(3/2019), s. 149–157. Fulltekst i vitenarkiv Vis sammendrag

  The red-listed orchid Ophrys insectifera is in decline despite years of protection. One of the species’ most important habitats is seasonally moist calcareous pine forest. This characteristic and species-rich forest type is especially well developed in Røsskleiva nature reserve in Langesund, Bamble, Telemark. A cattle grazing management regime was implemented in the reserve in 2017. As a basis for evaluation the management measures, as well as to document changes in the vegetation in general and the O. insectifera population in particular, we re-analysed 10 permanent plots established in Røsskleiva in the 1980s. The re-analyses, as well as surveys outside the plots, show a sharp decline in the O. insectifera population in the reserve from 1984 to 2017. The decrease in the O. insectifera population is coupled with marked vegetation changes, including increased cover of the shrub and tree layers. These changes are most likely driven by cessation of traditional use. The new management regime will hopefully restore favourable conditions for O. insectifera and other light-demanding species, but it remains to be seen if the O. insectifera population is able to recover.

• Kistenich, Sonja; Halvorsen, Rune; Schrøder-Nielsen, Audun; Thorbek, Birgitte Lisbeth Graae; Timdal, Einar & Bendiksby, Mika (2019). DNA Sequencing Historical Lichen Specimens. Frontiers in Ecology and Evolution. 7. doi: 10.3389/fevo.2019.00005. Fulltekst i vitenarkiv Vis sammendrag

  Biological specimens in natural history collections worldwide are increasingly being used in biogeographical, environmental, and taxonomic studies. For their meaningful use, correct species identification is crucial. For example, clarifying if a species is new to science requires an overview of what has already been described. This includes comparisons with existing authoritative specimens (types). Most type specimens are rather old and their DNA expected to be degraded to various extents. Comparative DNA sequence analysis is in regular use in taxonomic research of today and is essential for identifying and delimiting species. In this study, we focus on lichenized fungi (lichens), in which many species groups are highly inconspicuous and impossible to identify to species based on morphology alone. Our aim was to test the non-mutually exclusive hypotheses that DNA quality of lichens depends on (1) time since collection, (2) taxonomic affinity, and/or (3) habitat/ecology. We included two species from each of four different lichen genera (i.e., Cladonia, Nephroma, Peltigera, and Ramalina), each species pair with a different autecology. For each species, we included samples from approximately every 25 years from present to about 150 years back in time. We used a two-step PCR-based approach followed by sequencing on an Ion Torrent PGM to produce target sequences (mtSSU) of degraded DNA. We received satisfactory DNA sequence information for 54 of 56 specimens. We recovered full-length sequences for several more than 100-years-old specimens, including a 127-years-old specimen, and retrieved enough sequence information for species identification of a 150-years-old specimen. As expected, sequencing success was negatively correlated with age of the specimens. It also varied with taxonomic affinity. We found no significant correlation between sequencing success and habitat ecology of the investigated specimens. The herein tested Ion Torrent sequencing approach outperformed Sanger sequencing with regard to sequencing success and efficiency. We find the protocol used herein highly suitable for obtaining sequences from both young and old lichen specimens and discuss potential improvements to it.

• Vollering, Julien; Halvorsen, Rune & Mazzoni, Sabrina (2019). The MIAmaxent R package: Variable transformation and model selection for species distribution models. Ecology and Evolution. 9(21), s. 1–14. doi: 10.1002/ece3.5654. Fulltekst i vitenarkiv Vis sammendrag

  The widely used “Maxent” software for modeling species distributions from presence‐only data (Phillips et al., Ecological Modelling, 190, 2006, 231) tends to produce models with high‐predictive performance but low‐ecological interpretability, and implications of Maxent's statistical approach to variable transformation, model fitting, and model selection remain underappreciated. In particular, Maxent's approach to model selection through lasso regularization has been shown to give less parsimonious distribution models—that is, models which are more complex but not necessarily predictively better—than subset selection. In this paper, we introduce the MIAmaxent R package, which provides a statistical approach to modeling species distributions similar to Maxent's, but with subset selection instead of lasso regularization. The simpler models typically produced by subset selection are ecologically more interpretable, and making distribution models more grounded in ecological theory is a fundamental motivation for using MIAmaxent. To that end, the package executes variable transformation based on expected occurrence–environment relationships and contains tools for exploring data and interrogating models in light of knowledge of the modeled system. Additionally, MIAmaxent implements two different kinds of model fitting: maximum entropy fitting for presence‐only data and logistic regression (GLM) for presence–absence data. Unlike Maxent, MIAmaxent decouples variable transformation, model fitting, and model selection, which facilitates methodological comparisons and gives the modeler greater flexibility when choosing a statistical approach to a given distribution modeling problem.

• Horvath, Peter; Halvorsen, Rune; Stordal, Frode; Tallaksen, Lena Merete; Tang, Hui & Bryn, Anders (2019). Distribution modelling of vegetation types based on area frame survey data. Applied Vegetation Science. ISSN 1402-2001. 22(4), s. 547–560. doi: 10.1111/avsc.12451. Fulltekst i vitenarkiv Vis sammendrag

  Aim: Many countries lack informative, high‐resolution, wall‐to‐wall vegetation or land cover maps. Such maps are useful for land use and nature management, and for input to regional climate and hydrological models. Land cover maps based on remote sensing data typically lack the required ecological information, whereas traditional field‐based mapping is too expensive to be carried out over large areas. In this study, we therefore explore the extent to which distribution modelling (DM) methods are useful for predicting the current distribution of vegetation types (VT) on a national scale. Location: Mainland Norway, covering ca. 324,000 km2. Methods: We used presence/absence data for 31 different VTs, mapped wall‐to‐wall in an area frame survey with 1081 rectangular plots of 0.9 km2. Distribution models for each VT were obtained by logistic generalised linear modelling, using stepwise forward selection with an F‐ratio test. A total of 116 explanatory variables, recorded in 100 m × 100 m grid cells, were used. The 31 models were evaluated by applying the AUC criterion to an independent evaluation dataset. Results: Twenty‐one of the 31 models had AUC values higher than 0.8. The highest AUC value (0.989) was obtained for Poor/rich broadleaf deciduous forest, whereas the lowest AUC (0.671) was obtained for Lichen and heather spruce forest. Overall, we found that rare VTs are predicted better than common ones, and coastal VTs are predicted better than inland ones. Conclusions: Our study establishes DM as a viable tool for spatial prediction of aggregated species‐based entities such as VTs on a regional scale and at a fine (100 m) spatial resolution, provided relevant predictor variables are available. We discuss the potential uses of distribution models in utilizing large‐scale international vegetation surveys. We also argue that predictions from such models may improve parameterisation of vegetation distribution in earth system models.

• Vollering, Julien Martin Marie; Halvorsen, Rune; Auestad, Inger & Rydgren, Knut (2019). Bunching up the background betters bias in species distribution models. Ecography. ISSN 0906-7590. 42, s. 1–11. doi: 10.1111/ecog.04503. Fulltekst i vitenarkiv Vis sammendrag

  Sets of presence records used to model species’ distributions typically consist of observations collected opportunistically rather than systematically. As a result, sampling probability is geographically uneven, which may confound the model's characterization of the species’ distribution. Modelers frequently address sampling bias by manipulating training data: either subsampling presence data or creating a similar spatial bias in non‐presence background data. We tested a new method, which we call ‘background thickening’, in the latter category. Background thickening entails concentrating background locations around presence locations in proportion to presence location density. We compared background thickening to two established sampling bias correction methods – target group background selection and presence thinning – using simulated data and data from a case study. In the case study, background thickening and presence thinning performed similarly well, both producing better model discrimination than target group background selection, and better model calibration than models without correction. In the simulation, background thickening performed better than presence thinning when the number of simulated presence locations was low, and vice versa. We discuss drawbacks to target group background selection, why background thickening and presence thinning are conservative but robust sampling bias correction methods, and why background thickening is better than presence thinning for small sample sizes. Particularly, background thickening is advantageous for treating sampling bias when data are scarce because it avoids discarding presence records.

• Rydgren, Knut; Halvorsen, Rune; Töpper, Joachim Paul; Auestad, Inger; Hamre, Liv Norunn & Jongejans, Eelke [Vis alle 7 forfattere av denne artikkelen] (2019). Advancing restoration ecology: A new approach to predict time to recovery. Journal of Applied Ecology. ISSN 0021-8901. 56(1), s. 225–234. doi: 10.1111/1365-2664.13254. Fulltekst i vitenarkiv Vis sammendrag

  1. Species composition is a vital attribute of any ecosystem. Accordingly, ecological restoration often has the original, or “natural,” species composition as its target. However, we still lack adequate methods for predicting the expected time to compositional recovery in restoration studies. 2. We describe and explore a new, ordination regression-based approach (ORBA) for predicting time to recovery that allows both linear and asymptotic (logarithmic) relationships of compositional change with time. The approach uses distances between restored plots and reference plots along the successional gradient, represented by a vector in ordination space, to predict time to recovery. Thus, the approach rests on three requirements: (a) the general form of the relationship between compositional change and time must be known; (b) a sufficiently strong successional gradient must be present and adequately represented in a species compositional dataset; and (c) a restoration target must be specified. We tested the approach using data from a boreal old-growth forest that was followed for 18 years after experimental disturbance. Data from the first 9 years after disturbance were used to develop models, the subsequent 9 years for validation. 3. Rates of compositional recovery in the example dataset followed the general pattern of decrease with time since disturbance. Accordingly, linear models were too optimistic about the time to recovery, whereas the asymptotic models provided more precise predictions. 4. Synthesis and applications. Our results demonstrate that the new approach opens for reliable prediction of recovery rates and time to recovery using species compositional data. Moreover, it allows us to assess whether recovery proceeds in the desired direction and to quantitatively compare restoration speed, and hence effectiveness, between alternative management options. ordination, prediction, recovery, reference, restoration ecology, species composition, successional gradient, time to recovery

• Rydgren, Knut; Auestad, Inger; Halvorsen, Rune; Hamre, Liv Norunn; Jongejans, Eelke & Töpper, Joachim Paul [Vis alle 7 forfattere av denne artikkelen] (2019). Assessing restoration success by predicting time to recovery- But by which metric? Journal of Applied Ecology. ISSN 0021-8901. 57(2). doi: 10.1111/1365-2664.13526. Fulltekst i vitenarkiv Vis sammendrag

  1. Restoration of degraded ecosystems may take decades or even centuries. Accordingly, information about the current direction and speed of recovery provided by methods for predicting time to recovery may give important feedback to restoration schemes. While predictions of time to recovery have so far been based mostly upon change in species richness and other univariate predictors, the novel ordination-regression based approach (ORBA) affords a multivariate approach based upon species compositional change. 2. We used species composition data from four alpine spoil heaps in western Norway, recorded at three time points, to predict time to recovery using ORBA. This approach uses distances between restored plots and reference plots along a successional gradient, represented by a vector in ordination space, to model linear or asymptotic relationships of compositional change as a function of time. Results from ORBA were compared with results from models of more generic univariate attributes, that is total cover, species richness and properties of the physical environment as functions of time. 3. ORBA predictions of time to species compositional recovery varied from less than 60 years with linear models to 115–212 years with asymptotic models. The long estimated time to recovery suggests that the restoration schemes adopted for these spoil heaps are likely to be suboptimal. 4. Much shorter time to recovery was predicted from some of the more generic univariate attributes, that is species richness and total cover, than from species composition. Given the current rates of recovery, most spoil heaps will reach reference levels for total cover and species richness within 50 years, whereas predictions indicate that 67–111 years are needed to restore levels of soil organic matter and pH. 5. Synthesis and applications. Species composition and soil conditions provide information of generally higher relevance for evaluation of ecosystem recovery processes than the most commonly used metric to assess restoration success, species richness. Species richness is decoupled from species compositional recovery, and likely to be a generally poor measure of restoration success. We therefore encourage further improvement of methods like the ordination-regression based approach that use species compositional data to predict time to recovery. ORBA, Ordination-Regression Based Approach, restoration ecology, soil conditions, species composition, species richness, spoil heaps, time to recovery

• Eriksen, Eva Lieungh; Ullerud, Heidrun Asgeirsdatter; Halvorsen, Rune; Aune, Sigrun; Bratli, Harald & Horvath, Peter [Vis alle 9 forfattere av denne artikkelen] (2018). Point of view: error estimation in field assignment of land-cover types. Phytocoenologia. ISSN 0340-269X. 49(2), s. 135–148. doi: 10.1127/phyto/2018/0293. Fulltekst i vitenarkiv Vis sammendrag

  Questions: Substantial variation between observers has been found when comparing parallel land-cover maps, but how can we know which map is better? What magnitude of error and inter-observer variation is expected when assigning land-cover types and is this affected by the hierarchical level of the type system, observer characteristics, and ecosystem properties? Study area: Hvaler, south-east Norway. Methods: Eleven observers assigned mapping units to 120 stratified random points. At each observation point, the observers first assigned a mapping unit to the point independently. The group then decided on a ‘true’ reference mapping unit for that point. The reference was used to estimate total error. ‘Ecological distance’ to the reference was calculated to grade the errors. Results: Individual observers frequently assigned different mapping units to the same point. Deviating assignments were often ecologically close to the reference. Total error, as percentage of assignments that deviated from the reference, was 35.0% and 16.4% for low and high hierarchical levels of the land-covertype system, respectively. The corresponding figures for inter-observer variation were 42.8% and 19.4%, respectively. Observer bias was found. Particularly high error rates were found for land-cover types characterised by human disturbance. Conclusions: Access to a ‘true’ mapping unit for each observation point enabled estimation of error in addition to the inter-observer variation typically estimated by the standard pairwise comparisons method for maps and observers. Three major sources of error in the assignment of land-cover types were observed: dependence on system complexity represented by the hierarchical level of the land-cover-type system, dependence on the experience and personal characteristics of the observers, and dependence on properties of the mapped ecosystem. The results support the necessity of focusing on quality in land-cover mapping, among commissioners, practitioners and other end users.

Se alle arbeider i NVA

• Edvardsen, Anette; Halvorsen, Rune; Bratli, Harald; Bryn, Anders; Dervo, Børre Kind & Erikstad, Lars [Vis alle 11 forfattere av denne artikkelen] (2024). Natur i Norge. Variasjon satt i system. Universitetsforlaget. ISBN 9788215069869. 434 s. Fulltekst i vitenarkiv
• Dervo, Børre Kind; Brabrand, Åge; Erikstad, Lars; Halvorsen, Rune; Mjelde, Marit & Schartau, Ann Kristin [Vis alle 7 forfattere av denne artikkelen] (2022). Metodehåndbok. Kartleggingsmetodikk for NiN limnisk med vekt på natursystemet. Norsk institutt for naturforskning (NINA). ISBN 9788242648655. 80 s. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Fakhri, Arvin; Birkemoe, Tone; Eiterjord, Gaute; Gobakken, Terje; Halvorsen, Rune & Kauserud, Håvard [Vis alle 9 forfattere av denne artikkelen] (2025). Optimized vegetation index for detecting standing deadwood in boreal forests using airborne laser scanning and multispectral aerial imagery. Fulltekst i vitenarkiv Vis sammendrag

  Standing deadwood detection is critical for assessing forest health and biodiversity. This study presents an optimization-based method to identify standing dead trees in a boreal forest using Airborne Laser Scanning (ALS) and aerial multispectral (R, G, B, NIR) imagery. A canopy height model (accuracy 0.2 m) was derived from ALS data, and individual tree crowns were delineated with the Marker-Controlled Watershed Segmentation (MCWS) algorithm. Forty living and forty dead crowns were used to optimize a vegetation index (VI) of the form VI = a0 + a1R + a2G + a3B + a4NIR using the Cognitive Adaptive Swarm Optimization (CASO) algorithm. The model converged with an F1-score of 0.976 and optimal weights: a0= 0.499, a1 = 1.983, a2 = 1.864, a3 = 0.208, a4 = −1.359. The optimized VI effectively discriminated deadwood from live trees, demonstrating a robust, transferable framework for remote sensing-based forest monitoring in boreal environments.

• Vloon, Catharina Caspara; Halvorsen, Rune; Nordbakken, Jørn-Frode; Naas, Adam Eindride; Auestad, Inger & Rydgren, Knut (2025). Restoration of a boreal raised bog: does the state of the reference affect predicted time to recovery? Fulltekst i vitenarkiv
• Rydgren, Knut; Andersen, Roxane; Halvorsen, Rune; Hancock, Mark H.; Hughes, Robert D. & Martin-Walker, Alice [Vis alle 8 forfattere av denne artikkelen] (2025). Restoration of formerly afforested blanket bog: how long does vegetation recovery take. Fulltekst i vitenarkiv
• Naas, Adam Eindride; Horvath, Peter; Halvorsen, Rune; Sivertsen, Bendik & Bryn, Anders (2025). Garbage in, garbage out – propagation of errors from reference data to ecosystem distribution models. Fulltekst i vitenarkiv
• Tjessem, Ingrid Vesterdal; Bryn, Anders; Horvath, Peter; Naas, Adam Eindride; Halvorsen, Rune & Berntsen, Terje Koren [Vis alle 10 forfattere av denne artikkelen] (2025). Tales from the past: remapping rising tree- and forest lines in response to changing climate and land use regimes. Fulltekst i vitenarkiv
• Naas, Adam Eindride; Simensen, Trond; Keetz, Lasse Torben; Tjessem, Ingrid Vesterdal; Bryn, Anders & Halvorsen, Rune [Vis alle 13 forfattere av denne artikkelen] (2025). Ecosystem distribution models to support area management – a case study from Norway. Fulltekst i vitenarkiv
• Rydgren, Knut; Andersen, Roxane; Halvorsen, Rune; Hancock, Mark H.; Hughes, Robert D. & Martin-Walker, Alice [Vis alle 8 forfattere av denne artikkelen] (2025). Restoration of previously afforested blanket bogs in the Flow Country: how long does vegetation recovery take? Fulltekst i vitenarkiv
• Eiterjord, Gaute; Gobakken, Terje; Halvorsen, Rune; Kauserud, Håvard; Sverdrup-Thygeson, Anne & Ørka, Hans Ole [Vis alle 8 forfattere av denne artikkelen] (2025). BioDivAbove: Mapping forest biodiversity using airborne laser scanning and metabarcoding​. Fulltekst i vitenarkiv
• Vandvik, Vigdis; Armstrong, Claire W.; Barton, David Nicholas; Bekkby, Trine; Bjærke, Marit Ruge & Czúcz, Bálint [Vis alle 25 forfattere av denne artikkelen] (2025). Demokratisk fallitt i naturpolitikken? Khrono.no. ISSN 1894-8995. Fulltekst i vitenarkiv
• Bryn, Anders; Halvorsen, Rune; Horvath, Peter; Keetz, Lasse Torben; Mienna, Ida Marielle & Simensen, Trond [Vis alle 12 forfattere av denne artikkelen] (2025). Ecosystem distribution models to support area management - a case study from Norway. Fulltekst i vitenarkiv
• Bryn, Anders & Halvorsen, Rune (2024). Hva skal vi verne? Natur i Norge 3.0 kan gi bedre beslutninger mer effektivt. [Internet]. https://www.titan.uio.no. Fulltekst i vitenarkiv
• Storaunet, Ken Olaf; Sverdrup-Thygeson, Anne; Halvorsen, Rune & Rolstad, Jørund (2024). Naturskog og gammelskog: Hva er hva, og hva er ståa? Fulltekst i vitenarkiv
• Vandvik, Vigdis; Armstrong, Claire W.; Barton, David Nicholas; Bekkby, Trine; Bjærke, Marit Ruge & Czúcz, Bálint [Vis alle 25 forfattere av denne artikkelen] (2024). Stortinget må sette kunnskapen i arbeid for å stoppe naturtapet. Fulltekst i vitenarkiv
• Ronold, Eivind Kverme; Maurice, Sundy; Torp, Vilde Åvesland; Kostich-Nilsen, Celina Alexandria; Methlie, Ine-Susanne Hopland & Schmidt, Frida [Vis alle 17 forfattere av denne artikkelen] (2024). USING eDNA TO ASSESS THE EFFECTS OF CLEAR-CUTTING FORESTRY ON FUNGAL DIVERSITY IN BOREAL SPRUCE FORESTS. Fulltekst i vitenarkiv
• Ronold, Eivind Kverme; Kauserud, Håvard; Halvorsen, Rune; Morgado, Luis & Mundra, Sunil (2024). To what extent does vegetation structure fungal communities in boreal forests? Fulltekst i vitenarkiv
• Dolan, Margaret; Haugland, Barbro Taraldset; Bekkby, Trine; Thormar, Jonas; Son, Thijs Christiaan van & Halvorsen, Rune [Vis alle 10 forfattere av denne artikkelen] (2024). Nature in Norway (NiN) – describing and classifying properties of nature: Relevance for seabed habitat mapping. Fulltekst i vitenarkiv
• Naas, Adam Eindride; Keetz, Lasse Torben; Halvorsen, Rune; Horvath, Peter; Simensen, Trond & Mienna, Ida Marielle [Vis alle 7 forfattere av denne artikkelen] (2023). Distribution modelling of ecosystems in Norway - comparison of two modelling approaches and different types of predictors. Fulltekst i vitenarkiv
• Naas, Adam Eindride; Bryn, Anders; Halvorsen, Rune; Horvath, Peter; Keetz, Lasse Torben & Mienna, Ida Marielle [Vis alle 7 forfattere av denne artikkelen] (2023). Dynamic predictors improve ecosystem models. Fulltekst i vitenarkiv
• Naas, Adam Eindride; Halvorsen, Rune; Horvath, Peter; Wollan, Anders Kvalvåg; Bratli, Harald & Brynildsrud, Katrine Marie [Vis alle 16 forfattere av denne artikkelen] (2023). How consistent are NiN field mappers? Fulltekst i vitenarkiv
• Halvorsen, Rune & Bryn, Anders (2023). Hvorfor mangler naturkartlegging tillit? Fulltekst i vitenarkiv
• Vloon, Catharina Caspara; Halvorsen, Rune; Nordbakken, Jørn-Frode; Auestad, Inger & Rydgren, Knut (2023). Restoration of a boreal ombrogenous mire: predicting time to recovery after ditch blocking. Fulltekst i vitenarkiv
• Storaunet, Ken Olaf; Rolstad, Jørund; Skarpaas, Olav & Halvorsen, Rune (2023). Hva er naturlig dynamikk i skoglandskapet? Norsk Skogbruk. ISSN 0029-2087. s. 52–54. Fulltekst i vitenarkiv
• Schuuring, Sil; Halvorsen, Rune; Eidesen, Pernille Bronken; Nyttinen, Pekka; Kemppinen, Julia & Lang, Simone (2023). No need to be bushy: Low-statured high arctic vegetation slows early season active layer thaw. Fulltekst i vitenarkiv
• Halvorsen, Rune (2023). Peatlands: origin, dynamics, pattern and processes. Fulltekst i vitenarkiv
• Töpper, Joachim Paul; Bakkestuen, Vegar; Evju, Marianne; Halvorsen, Rune; Jokerud, Mari & Kvamme, Mons [Vis alle 9 forfattere av denne artikkelen] (2023). Fire tiår med og for naturen – Per Arild Aarrestad. Blyttia : Norsk botanisk forenings tidsskrift. ISSN 0006-5269. 81(1), s. 12–19. Fulltekst i vitenarkiv
• Bendiksby, Mika; Thorbek, Birgitte Lisbeth Graae; Bjorå, Charlotte Sletten & Halvorsen, Rune (2022). Simple procedures for obtaining DNA sequences from old herbarium specimens. Fulltekst i vitenarkiv
• Velle, Liv Guri; Töpper, Joachim Paul; Chipperfield, Joseph; Halvorsen, Rune; Seddon, Alistair William Robin & Vandvik, Vigdis (2022). ECoMAP: Modelling Ecological state and Condition Maps to support knowledge-based decision-making in Area management and spatial Planning. Fulltekst i vitenarkiv
• Vollering, Julien; Aakre, Gina & Halvorsen, Rune (2022). Sitkagranen har de mest produktive årene foran seg og stortrives i norsk klima. [Internet]. titan.uio.no. Fulltekst i vitenarkiv
• Halvorsen, Rune; Brenn, Odd Arne; Framstad, Erik; Gaarder, Geir; Gjerde, Ivar & Schei, Fride Høistad [Vis alle 9 forfattere av denne artikkelen] (2022). Framlegg til revidert beskrivelse av skogdynamikk i NiN. I Skarpaas, Olav & Halvorsen, Rune (Red.), Skogens dynamikk, struktur og artsmangfold - bakgrunnskunnskap for en ny beskrivelse av skogbestandsdynamikk i NiN. Naturhistorisk museum, UiO. ISSN 9788279701415. s. 85–115. Fulltekst i vitenarkiv
• Skarpaas, Olav; Son, Thijs Christiaan van; Halvorsen, Rune & Storaunet, Ken Olaf (2022). Samvariasjon mellom strukturvariabler i norsk skog – en analyse basert på Landsskogtakseringens data. I Skarpaas, Olav & Halvorsen, Rune (Red.), Skogens dynamikk, struktur og artsmangfold - bakgrunnskunnskap for en ny beskrivelse av skogbestandsdynamikk i NiN. Naturhistorisk museum, UiO. ISSN 9788279701415. s. 58–68. Fulltekst i vitenarkiv
• Velle, Liv Guri; Töpper, Joachim Paul; Chipperfield, Joseph; Halvorsen, Rune; Seddon, Alistair William Robin & Vandvik, Vigdis (2022). ECoMAP: Modelling Ecological state and Condition Maps to support knowledge-based decision-making in Area management and spatial Planning. Fulltekst i vitenarkiv
• Schuuring, Sil; Eidesen, Pernille Bronken; Halvorsen, Rune & Lang, Simone (2021). High Arctic Bryophytes: A green Blanket? Fulltekst i vitenarkiv
• Økland, Tonje & Halvorsen, Rune (2020). TOV granskog: Utvikling i bakkevegetasjonen og dens artsmangfold i ni områder med gammel, vernet granskog. Utvalgte overvåkingsresultater 1988–2019. Skogens helsetilstand i Norge. Resultater fra skogskadeovervåkingen i 2019. NIBIO. ISSN 9788217023876. s. 39–46. Fulltekst i vitenarkiv Vis sammendrag

  Skogens helsetilstand påvirkes i stor grad av klima og værforhold, enten direkte ved tørke, frost og vind, eller indirekte ved at klimaet påvirker omfanget av soppsykdommer og insektangrep. Klimaendringene og den forventede økningen i klimarelaterte skogskader gir store utfordringer for forvaltningen av framtidas skogressurser. Det samme gjør invaderende skadegjørere, både allerede etablerte arter og nye som kan komme til Norge i nær framtid. I denne rapporten presenteres resultater fra skogskadeovervåkingen i Norge i 2019 og trender over tid.....

• Økland, Tonje; Aarrestad, Per Arild; Bakkestuen, Vegar & Halvorsen, Rune (2020). Mengdeendringer for utvalgte plantearter 1988–2019. I Framstad, Erik (Red.), Terrestrisk naturovervåking i 2019: Markvegetasjon, epifytter, smågnagere og fugl. Sammenfatning av resultater. Norsk institutt for naturforskning (NINA). ISSN 9788242645579. s. 48–54. Fulltekst i vitenarkiv Vis sammendrag

  Framstad, E. (ed.) 2019. Terrestrial Ecosystems Monitoring in 2017: Ground vegetation, epiphytes, small mammals and birds. Summary of results. NINA Report 1608. Norwegian Institute for Nature Research. The TOV Monitoring Program started in 1990 and covers common plants and animals in 6 birch forest and 11 spruce forest sites. Here, we compare results from 2017 to those from previous years. Since 1997, the ground vegetation in Møsvatn has changed from domination by dwarf shrubs to slightly richer vegetation with herbs and grasses. This is partly due to atmospheric nitrogen deposition. Several moth attacks have supplied nitrogen from excrements and reduced crown cover. Along with longer and milder fall growing seasons, this has led to increased nutrient supply to plants. The ground vegetation in spruce forest in Gutulia National Park showed significant decline in the number of species of vascular plants, bryophytes and lichens recorded in 2017, both from 1989 and since the last survey (2009). Since 1989, 14 vascular plant species and 16 species of bryophytes have declined in quantity; only one peat moss has increased. The species composition has changed towards vegetation on nutrient-poor sites. In Møsvatn, the cover of epiphytes on birch trees has increased over the monitoring period to over 100%. The amount of fruticose lichens has increased since 2012, while the increase in foliose lichens has stopped. The proportion of damaged lichens is small and lower than in 2012. The changes reflect less sulphur deposition and favourable climate development with longer growing season, increased temperature and precipitation. During 2014-2017, Dividalen had outbreaks of birch moths in 2014, and there is an increase in their incidence in other areas, with significant damage to birch leaves in Åmotsdalen in 2017. Small rodents show rather regular population peaks in Møsvatn, Åmotsdalen and Børgefjell, but more irregular and lower peaks in other areas. In 2017, there were relatively high populations of small rodents in Møsvatn and Åmotsdalen, lower peaks in Solhomfjell, Finse and Gutulia, and low years in Børgefjell and Dividalen. Few rodents were caught in Lund, but some individuals were observed. In most areas, bank voles and partly field voles dominated, except at Finse where lemmings and tundra voles dominated. In 2017, production of young in golden eagles was somewhat below average for the monitoring period for Børgefjell, Møsvatn, Gutulia and Lund and somewhat above at Åmotsdalen and Solhomfjell. Production in 2017 was nevertheless somewhat higher than in 2016 for most of southern Norway, probably due to larger rodent populations and better supply of grouse and other prey. Production of young in gyrfalcons was lower in 2017 than in 2016, roughly the average for the monitoring period in Møsvatn and lower in Børgefjell and Åmotsdalen. Surveys of willow grouse in 2017 showed few changes from 2016 for most TOV areas. In Børgefjell and Lund few grouse were observed. Dividalen was also estimated to have rather low densities, while estimates for Åmotsdalen were quite high. For Møsvatn, more grouse and higher production of young were observed than in any previous years. In 2017, observations of stationary passerine birds were above the median for the monitoring period for Dividalen, Åmotsdalen and Lund and below for other areas. In the mountains, observations in the last 10 years were lower than in the previous 10-year period. Decline in passerine birds is also documented for other mountain areas in Fennoscandia. Production of young in pied fly catchers was generally good in all four areas with such studies. There is good correlation between hatching times and May temperatures, but they do not show any trend over the monitoring period. The representative monitoring of nesting birds showed the most observations of willow warbler (17.5%), meadow pipit (7.4%) and chaffinch (6.6%). Over the last 10 years, monitoring shows a clear decline for 26 of 76 bird species with sufficient data and increase for 10 species. Species with population decline are especially associated with agricultural landscapes and mountains, but also include some forest species.

• Økland, Tonje; Halvorsen, Rune & Nordbakken, Jørn-Frode (2019). VEGETASJONSOVERVÅKING I GAMMEL GRANSKOG I TOV Hva kan den mer enn 30 år lange tidsserien bidra med til «Fagsystem for god økologisk tilstand»/ANO/Naturindeks? Fulltekst i vitenarkiv
• Halvorsen, Rune; Økland, Tonje & Nordbakken, Jørn-Frode (2019). Videreføring av TOV granskog. Fulltekst i vitenarkiv
• Halvorsen, Rune; Bratli, Harald & Wollan, Anders Kvalvåg (2019). Vegetasjonsundersøkelser av boreal barskog i Solhomfjell 2018. I Framstad, Erik (Red.), Terrestrisk naturovervåking i 2018: Markvegetasjon, epifytter, smågnagere og fugl. Sammenfatning av resultater. Norsk institutt for naturforskning (NINA). ISSN 9788242634429. s. 46–79. Fulltekst i vitenarkiv Vis sammendrag

  Overvåking av markvegetasjonen i gran- og furuskog har pågått i Solhomfjell-området siden 1988 (R. Økland & Eilertsen 1993). Overvåkingen i Solhomfjell ble i 2001 samorganisert med tilsvarende overvåking i regi av NIJOS (seinere Norsk institutt for skog og landskap og NIBIO) i granskog og NINA i bjørkeskog. Fra 2004 har alle disse vegetasjonsovervåkingsaktivitetene vært del av Program for terrestrisk naturovervåking (TOV). De tre overvåkingsaktivitetene for markvegetasjon som nå er samlet i TOV, var i utgangspunktet basert på ulike metoder for plassering av prøveflater (R. Økland & Eilertsen 1993, T. Økland 1996, Bakkestuen et al. 2010), men er seinere samordnet med sikte på å maksimere sammenliknbarhet (f.eks. T. Økland et al. 2001, 2004a, 2004b). Undersøkelsen i Solhomfjell skiller seg imidlertid (fortsatt) fra undersøkelsene i de øvrige områdene som inngår i TOV på tre måter: (1) Prøveflatene er plassert langs transekter i stedet for i 50-m2 makroruter. (2) I tillegg til å utspenne den lokale komplekse miljøgradienten kalkinnhold (mineralnæringsinnhold; KA i NiN-terminologi, jf. Halvorsen et al. 2015), fra kalkfattig via intermediær til (svakt) kalkrik, favner Solhomfjell-materialet hele uttørkingsfare-gradienten (UF i NiN) fra frisk, blåbærdominert granskog, inkludert fuktmarksutforminger [se R. Økland & Eilertsen (1993) og T. Økland (1996) for definisjon av begrepet 'blåbærdominert granskog'] via bærlyngskog (blandingsskog av gran og furu) og furu-dominert lyngskog, til svært tørkeutsatt, furudominert lavskog. Flater med svak kildevannspå-virkning (KI; overganger mellom lågurtskog og høgstaudeskog) inngår også. (3) Prøveflateantallet er 100 (et utvalg av de 200 flatene som opprinnelig ble plassert og analysert i 1988 og 1993) og ikke 50 flater som i de andre TOV-områdene. Vegetasjonen i prøveflatene i Solhomfjell ble første gang analysert i 1988. Deretter har 100 flater blitt analysert hvert 5. år: i 1993, 1998, 2003, 2008, 2013 og foreløpig siste gang i 2018. 50 av prøveflatene ble dessuten analysert hvert år mellom 1988 og 1993, samt i 1995. I 1988 og 1993 ble grundige registreringer av økologiske forklaringsvariabler registrert i tilknytning til hver av de 200 analyserte prøveflatene. For å identifisere hovedgradienter i artssammensetning og å relatere disse til komplekse miljøgradienter, ble det foretatt en vegetasjonsøkologisk basisundersøkelse av datamaterialet innsamlet i 1988 (R. Økland & Eilertsen 1993). De årlige undersøkelsene av vegetasjon fram til og med 1993 dannet grunnlag for undersøkelser av artenes persistens (R. Økland 1995a, 1995b). Gjenanalysedatasettet fra 1993 ble også grundig analysert med hensyn til endringer i vegetasjon og miljøvariabler (R. Økland 1995c, 1995d, R. Økland & Eilertsen 1996). Seinere gjenanalyser er, med unntak av datamaterialet som ble samlet inn i 1998, og som er grunnlag for artikkelen T. Økland et al. (2004a), rapportert i enklere form (R. Økland 1997a, R. Økland et al. 2000, R. Økland & Nordbakken 2004, Halvorsen et al. 2009b, 2014). I denne rapporten oppsummeres endringsmønstre for arter og vegetasjon i Solhomfjell-området 1988–2018, med særlig vekt på femårsperioden 2013–18. Parallelt med vegetasjonsundersøkelsen har det siden 1990 blitt gjennomført populasjonsbiologiske undersøkelser av etasjemose i granskog i Solhomfjell og i seks andre overvåkingsområder (R. Økland 1995e). Disse undersøkelsene blir rapportert i kapittel 7.

• Dolan, Margaret; Bekkby, Trine; Buhl-Mortensen, Pål; Andersen, Guri Sogn; Son, Thijs Christiaan van & Thormar, Jonas [Vis alle 11 forfattere av denne artikkelen] (2019). Phasing in use of the “Nature in Norway” (NiN) system for classification and description of nature in the marine environment – experiences, challenges and international relevance. Fulltekst i vitenarkiv
• Økland, Tonje; Aarrestad, Per Arild; Bakkestuen, Vegar & Halvorsen, Rune (2019). Mengdeendringer for utvalgte plantearter 1988–2017. I Framstad, Erik (Red.), Terrestrisk naturovervåking i 2017: Markvegetasjon, epifytter, smågnagere og fugl. Sammenfatning av resultater. Norsk institutt for naturforskning. ISSN 9788242633491. s. 50–56. Fulltekst i vitenarkiv Vis sammendrag

  Program for terrestrisk naturovervåking startet i 1990 og omfatter undersøkelser av vanlige planter og dyr i 6 områder i bjørkeskog og 11 i granskog. Her ses resultatene fra 2017 i sammenheng med resultatene fra tidligere år. Markvegetasjonen i Møsvatn har siden 1997 endret seg fra fattige lyng- og bærlyngdominerte typer til svakt rikere lågurttyper med større innslag av gras og starr. Dette skyldes dels påvirkning av langtransportert nitrogen. Flere bjørkemålerangrep har også tilført nitrogen fra ekskrementer og gitt mer lys til bakken. Sammen med lengre og mildere vekstsesong på høsten har dette ført til noe mer baserikhet i jorda og økt næringstilgangen til plantene. Markvegetasjonen i granskog i Gutulia nasjonalpark viste i 2017 betydelig tilbakegang i antall registrerte arter av karplanter, moser og lav, både fra begynnelsen av overvåkingen i 1989 og siden forrige registrering (2009). Siden 1989 var det tilbakegang i mengde for 14 karplantearter og 16 mosearter; bare én torvmoseart økte i mengde. Artssammensetningen har endret seg mot vegetasjon på næringsfattige voksesteder. I Møsvatn har mengden epifytter på bjørketrær økt over overvåkingsperioden og er nå over 100 %. Mengde busklav har økt også siden 2012, mens økning i bladlav har stagnert. Andel skadd lav er liten og lavere enn i 2012. Endringene tyder på mindre svovelnedfall og gunstig klimautvikling med lengre vekstsesong, økt temperatur og nedbør. I perioden 2014-2017 har Dividalen hatt utbrudd av bjørkemålere i 2014, mens det har vært en økning i forekomst i øvrige områder, med betydelige beiteskader på bjørkeblader i Åmotsdalen i 2017. Smågnagere viser nokså regelmessige bestandstopper i Møsvatn, Åmotsdalen og Børgefjell, men mer uregelmessige og lavere topper i øvrige TOV-områder. I 2017 var det forholdsvis høye bestander av smågnagere i Møsvatn og Åmotsdalen, lavere topper i Solhomfjell, Finse og Gutulia, og bunnår i Børgefjell og Dividalen. Få smågnagere ble fanget i Lund, men en del individer ble observert. I de fleste områdene dominerte klatremus og til dels markmus i fangstene, bortsett fra på Finse der lemen og fjellmarkmus dominerte. Ungeproduksjonen for kongeørn lå i 2017 noe under gjennomsnittet for overvåkingsperioden for Børgefjell, Møsvatn, Gutulia og Lund og noe over for Åmotsdalen og Solhomfjell. Produksjonen i 2017 var likevel noe høyere enn i 2016 for de fleste områdene i Sør-Norge, trolig pga. større smågnagerbestander og bedre tilgang på ryper og annet bytte. Ungeproduksjonen for jaktfalk var lavere i 2017 enn i 2016, omtrent som gjennomsnittet for overvåkingsperioden i Møsvatn og lavere i Børgefjell og Åmotsdalen. Rypetakseringene i 2017 viste få endringer fra 2016 for de fleste TOV-områdene. I Børgefjell og Lund ble få ryper observert. Også i Dividalen ble det estimert nokså lave tettheter, mens estimatene for Åmotsdalen var ganske høye. For Møsvatn ble det observert flere ryper og høyere unge-produksjon enn i noen tidligere år. NØKKELORD : terrestrisk miljø, overvåking, klimavariasjon, forurensinger, naturlig dynamikk, markvegetasjon, epifytter, smågnagere, fugl, reproduksjon, bestandsvariasjoner, artssammensetning, Norge, KEY WORDS : terrestrial environment, monitoring, climate variation, pollution, natural Dynamics, ground vegetation, epiphytes, small rodents, birds, reproduction, population variation, species composition, Norway

• Simensen, Trond; Halvorsen, Rune; Erikstad, Lars & Bakkestuen, Vegar (2018). A gradient perspective on landscape classification. Fulltekst i vitenarkiv
• Bendiksen, Egil & Halvorsen, Rune (2025). Kjøttfe på utmarksbeite. Konsekvenser for lauvtreforyngelse. Undersøkelser i Mathiesen Eidsvold Værks skoger i Nannestad, Hurdal og Gran. Norsk institutt for naturforskning (NINA). ISSN 9788242654199. Fulltekst i vitenarkiv Vis sammendrag

  Norge, Akershus, Oppland, MEV, utmarksbeite, ammeku, skogsbeite, hogstflater

• Dervo, Børre Kind; Erikstad, Lars; Halvorsen, Rune; Mjelde, Marit & Schartau, Ann Kristin (2024). Metodehåndbok limnisk - Kartleggingsmetodikk og variabler (NiN 3.0), versjon 1. Artsdatabanken. ISSN 9788292838662. Fulltekst i vitenarkiv
• Bryn, Anders; Andersen, Guri Sogn; Bekkby, Trine; Bratli, Harald; Dervo, Børre Kind & Dolan, Margaret [Vis alle 14 forfattere av denne artikkelen] (2023). Hovedveileder for feltbasert kartlegging. Terrestrisk, limnisk og marin naturvariasjon etter NiN (3.0). Artsdatabanken. ISSN 9788292838617. Fulltekst i vitenarkiv
• Lyngstad, Anders; Moen, Asbjørn; Halvorsen, Rune & Øien, Dag-Inge (2023). Beskrivelser av torvmassivenheter. Kunnskapsgrunnlag for NiN 3.0. Norges teknisk-naturvitenskapelige universitet. ISSN 9788283223538. Fulltekst i vitenarkiv Vis sammendrag

  English summary A mire is defined as a land area with moisture-demanding vegetation that produces peat. Peat is autochton-ously accumulated material, with a dry fraction consisting of more than 30% organic material. The definition of mire does nor require a specific depth of the peat layer. A peatland is defined as an area with or without vegetation, with a naturally accumulated peat layer on top. Hence, all mires are peatlands but a peatland is not necessarily a mire. New estimates indicate that the mire area of Norway is 41 655 km2, consisting of 28 777 km2 open mire and 12 878 km2 forested mire and swamp. The total peatland area (including degraded peatland) is estimated to 48 655 km2. Nature in Norway version 3 (NiN 3) is an implementation for Norway of the theoretical EcoSyst framework for systematisation of Nature's variation. The two mire typologies in NiN 3 are based on vegetation, hydrology, hydromorphology and hydrogenetics. Hydrologic typologies address the origin and movement of water. Hydromorphology addresses the shape of mire massifs, distribution of mire sites, and the form and pattern of mire features. Hydrogenetics emphasise the processes leading to formation and development of peat and peatland. The mire ecosystems typology is based upon recognition of main ecological structuring processes, using species composition along ecological gradients to separate major and minor wetland ecosystem types. The mire massif typology uses hydrologic, hydromorphologic and hydrogenetic criteria to define mire massif units. The mire massif units are mire landforms, defined by the same principles and criteria as other landform categories in NiN 3, i.e. landforms in bedrock and sediments, river reaches, lake bassins and glacier massifs. The NiN 3 landform typologies are organised in two hierarchical levels. For mires, the first level is the mire massif group, and the second level is the mire massif unit. The mire typology includes 8 mire massif groups with a total of 22 mire massif units. The fundamental difference between minerogenous and ombrogenous peat is the basis for separating four minerogenous and two ombrogenous groups. Furthermore, the mixed mire group has structured occurrence of minerogenous and ombrogenous mire features, and the transitional mire group covers other mires with a mixture of minerogenous and ombrogenous elements. This yields the mire massif groups A Topogenous mire massifs, B Soligenous mire massifs, C Spring mire massifs, D Floodwater mire massifs, E Mixed mire massifs, F Transitional mire massifs, G Blanket bog mire massifs and H Raised bog mire massifs. The topogenous mire massif group has stagnant water, a plane water level, and contain the units A1 Terrestrialisation mire and A2 Flat fen. The soligenous mire massif group has a sloping surface and water level and are characterised by moving water. The units included are B1 Soligenous surface flow mire, B2 Percolation fen, B3 Sloping fen, B4 Low string-flark fen and B5 Medium string-flark fen. The spring mire massif group stand out by receiving a more or less constant flux of spring water and has one unit: C1 Spring fen. The floodwater mire massif group encompasses D1 Lake floodwater mire, D2 River floodwater mire and D3 Marine floodwater mire. This group is characterised by periodic flooding by water from rivers or lakes (limnogenous water), or by influence from tidal water (thalassogenous water). The mixed mire massif group includes E1 Islet mixed mire, E2 Palsa mire and E3 String-flark mixed mire. Mires in this group have ombrogenous structures formed by long-lasting frozen peat (E1, E3) or permafrost (E2). The mire massif unit F1 Transitional mire contains mire with a mixture of ombrogenous and minero-genous areas, and that do not fit into group E. Mires in this heterogeneous unit can be stable because their development is restricted by topographic barriers or climatic conditions. Most of them likely have not yet reached their hydromorphological potential, meaning they are currently developing towards another mire massif unit. Possible theoretical successional end points for transitional mires can be a raised bog mire massif unit, or a blanket bog mire massif unit. G1 Blanket bog mire massif unit follows the underlying terrain and lacks an ombrogenous peat dome. It is the sole mire massif unit of group G. Raised bogs mire massif group are characterised by an ombrogenous peat dome and include six mire massif units: H1 Atlantic raised bog, H2 Rim raised bog, H3 Plateau raised bog, H4 Concentric raised bog, H5 Wooded raised bog and H6 Eccentric raised bog. The four mire massif units H3 to H6 make up a group often referred to as typical raised bog. This is not a formalised mire massif group in NiN 3. Typical raised bogs are characterised by a more or less open mire expanse with ombrotrophic conditions, surrounded by a marginal forest, and a distinct lagg.

• Skarpaas, Olav & Halvorsen, Rune (2022). Skogens dynamikk, struktur og artsmangfold - bakgrunnskunnskap for en ny beskrivelse av skogbestandsdynamikk i NiN. Naturhistorisk museum, UiO. ISSN 9788279701415. Fulltekst i vitenarkiv
• Halvorsen, Rune; Wollan, Anders Kvalvåg; Bryn, Anders; Bratli, Harald & Horvath, Peter (2021). Naturtypekart etter NiN for området omkring Veia (Nedre Eiker og Øvre Eiker, Buskerud). Naturhistorisk museum. ISSN 9788279701262. Fulltekst i vitenarkiv
• Bratli, Harald; Halvorsen, Rune; Høitomt, Torbjørn; Ihlen, Per G. & Brynjulvsrud, John Gunnar (2021). Utvikling av kunnskapsgrunnlaget for beskrivelse av fossesprutsoner i Natur i Norge (NiN). Naturhistorisk museum. ISSN 9788279701255. Fulltekst i vitenarkiv
• Framstad, Erik; Bakkestuen, Vegar; Halvorsen, Rune; Kålås, John Atle; Myklebost, Heidi Elin & Nilsen, Erlend Birkeland [Vis alle 10 forfattere av denne artikkelen] (2020). Program for terrestrisk naturovervåking (TOV). Dokumentasjon av overvåkingsområder, metoder og data. Norsk institutt for naturforskning (NINA). ISSN 9788242645869. Fulltekst i vitenarkiv Vis sammendrag

  Norge, terrestrisk naturovervåking, dokumentasjon, områder, metoder, data, skog, fjell, vegetasjon, epifytter, bjørkemålere, smågnagere, fugler, Norway, terrestrial ecosystem monitoring, documentation, sites, methods, data, forest, mountains, vegetation, epiphytes, birch defoliating moths, small rodents, birds

• Halvorsen, Rune; Bryn, Anders; Bratli, Harald & Horvath, Peter (2020). Naturtypekart etter NiN for et område omkring Unsetsætra (Biri, Gjøvik, Oppland). Naturhistorisk Museum. ISSN 9788279701200. Fulltekst i vitenarkiv Vis sammendrag

  Denne rapporten gir en kortfattet beskrivelse av metadata for et naturtypekart etter NiN-metodikk, utarbeidet for et 500×500 m stort område omkring Unsetsætra, Biri, Gjøvik (Oppland). Kartet omfatter to kartlag, ett heldekkende kartlag for kartleggingsenheter etter NiN versjon 2.2 tilpasset kartlegging i målestokk 1:5000, og ett utvalgskartlag for spesifikke egenskaper fra NiNs beskrivelsessystem, som utfigureres som livsmiljøer i MiS-kartlegging (versjon 1.0.2) etter NiN. Resultatene presenteres som kart og tabeller. Som grunnlagsmateriale for feltkartleggingen ble ortofoto fra Norge Digitalt, skogbruksplandata fra Kilden (NIBIO) og topografiske kartdata fra N5 benyttet. Kartleggingen ble utført ved bruk av felt-PC med tilrettelagt oppsett i QGIS. Begge kartlagene er resultatet av at et feltbasert kartutkast, tegnet av én kartlegger, ble bearbeidet gjennom en konsensusprosess der tre kartleggere sammen i felt kontrollerte kartutkastet og drøftet seg fram til omforente løsninger på utfordringer knyttet til typetilordning og figuravgrensning. Rapporten inneholder kart og arealstatistikk for naturtyper og kartlagte egenskaper, samt en kortfattet drøfting av utfordringer ved kartleggingen og hvordan disse ble løst.

• Timmermann, Volkmar; Andreassen, Kjell; Beachell, Andreas Myki; Børja, Isabella; Brurberg, May Bente & Clarke, Nicholas [Vis alle 18 forfattere av denne artikkelen] (2020). Skogens helsetilstand i Norge. Resultater fra skogskadeovervåkingen i 2019. NIBIO. ISSN 9788217023876. Fulltekst i vitenarkiv Vis sammendrag

  Skogens helsetilstand påvirkes i stor grad av klima og værforhold, enten direkte ved tørke, frost og vind, eller indirekte ved at klimaet påvirker omfanget av soppsykdommer og insektangrep. Klimaendringene og den forventede økningen i klimarelaterte skogskader gir store utfordringer for forvaltningen av framtidas skogressurser. Det samme gjør invaderende skadegjørere, både allerede etablerte arter og nye som kan komme til Norge i nær framtid. I denne rapporten presenteres resultater fra skogskadeovervåkingen i Norge i 2019 og trender over tid.....

• Framstad, Erik; Bakkestuen, Vegar; Halvorsen, Rune; Ihlen, Per Gerhard; Nilsen, Erlend Birkeland & Olsen, Siri Lie [Vis alle 10 forfattere av denne artikkelen] (2020). TOV etter 2020. Utvikling av TOV som økosystembasert overvåking. Norsk institutt for naturforskning (NINA). ISSN 9788242646491. Fulltekst i vitenarkiv Vis sammendrag

  Overvåking, terrestriske økosystemer, vegetasjon, epifytter, fauna, modeller, integrasjon, adaptiv, monitoring, terrestrial ecosystems, vegetation, epiphytes, fauna, models, integration, adaptive

• Bryn, Anders; Bekkby, Trine; Dervo, Børre Kind; Dolan, Margaret & Halvorsen, Rune (2020). Hovedveileder for feltbasert kartlegging av terrestrisk, limnisk og marin naturvariasjon etter NiN. Artsdatabanken. ISSN 9788292838549. Fulltekst i vitenarkiv Vis sammendrag

  Formålet med veilederen er å fylle det kunnskapsrommet som trengs for å bruke natursystemnivået i NiN til feltbasert kartlegging; både til opplæring av nye kartleggere, til hjelp ved utlysning av oppdrag, og som veiledning for ulike brukere av naturtypekart. Feltbasert kartlegging etter NiN brukes og lyses ut for mange ulike formål, og veilederen bærer derfor preg av å skulle dekke mange ulike behov. Veilederen inkluderer kartlegging av terrestriske, limniske og marine økosystemer. Veilederen definerer ikke hvordan de enkelte sektorer skal løse sine kartleggingsbehov, men viser hvordan ulike behov og utfordringer kan løses. Formålet med veilederen er å bidra til at resultatene av praktisk kartlegging blir så gode som mulig. Naturtypekartenes kvalitet styres imidlertid i stor grad av rammer utenfor denne veilederen. Det er de ulike sektorene som organiserer og lyser ut oppdrag som avgjør hvordan kartleggingen i praksis foregår. Dette dokumentet er derfor en veileder, ikke en instruks.

• Bratli, Harald; Halvorsen, Rune; Bryn, Anders; Arnesen, Geir; Bendiksen, Egil & Jordal, Jon Bjarne [Vis alle 11 forfattere av denne artikkelen] (2019). Beskrivelse av kartleggingsenheter i målestokk 1:5000 etter NiN (2.2.0). Utgave 1, kartleggingsveileder nr 4. Artsdatabanken. ISSN 9788292838501. Fulltekst i vitenarkiv
• Halvorsen, Rune; Eriksen, Eva Lieungh; Wollan, Anders Kvalvåg; Ullerud, Heidrun Asgeirsdatter; Bryn, Anders & Bratli, Harald [Vis alle 7 forfattere av denne artikkelen] (2018). Forarbeid til standard for kontroll av kvalitet i naturtypekart etter NiN. FoU rapport 1. Artsdatabanken. ISSN 9788292838518. Fulltekst i vitenarkiv
• Bryn, Anders; Halvorsen, Rune & Ullerud, Heidrun Asgeirsdatter (2018). Hovedveileder for kartlegging av terrestrisk naturvariasjon i Norge (Version 2.2.0). Utgave 1. NiN-artikkel 7. Artsdatabanken. Fulltekst i vitenarkiv

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