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We measured community-level traits of vascular plants, lichens, and bryophytes in an alpine Dryas octopetala L. heath in Finse, Norway, after nearly two decades of experimental warming by open-top chambers. We hypothesized that under warming (1) vascular plant traits would shift from resource conservative towards more resource acquisitive, and (2) lichen and bryophyte traits would shift to those associated with drier conditions, due to increased evapotranspiration. Both hypotheses were not supported, as vascular plant nitrogen concentration decreased, whereas carbon to nitrogen ratio increased with warming, indicative of a less resource acquisitive strategy, and lichen specific thallus area and water holding capacity were unresponsive. Bryophyte specific shoot length increased, and carbon concentration and water holding capacity tended to decrease under warming, concurrent with increased vegetation height and litter cover indicating stronger competition from vascular plants. Intraspecific variation was most important for vascular plant and lichen traits, whereas species turnover was the main driver of bryophyte trait variation. This indicates that bryophytes may be affected more strongly by future warming than vascular plants and lichens in our study system. We highlight the importance of studying traits of different primary producer groups simultaneously, as they may respond differently to the same environmental changes.

The International Tundra Experiment (ITEX) was established to understand how environmental change impacts Arctic and alpine ecosystems. The success of the ITEX-network has allowed for several important across-site syntheses, and for some ITEX-sites enough data have now been collected to perform within-site syntheses on the effects of environmental change across ecological scales. In this study, we analyze climate data and synthesize three decades of research on the ecological effects of environmental change at the ITEX-site at Finse, southern Norway. We found a modest warming rate of +0.36 °C per decade and minor effects on growing season length. Maximum winter snow depth was highest in winters with a positive North Atlantic Oscillation. Our synthesis included 80 ecological studies from Finse, biased towards primary producers with few studies on ecological processes. Species distributions depended on microtopography and microclimate. Experimental warming had contrasting effects on abundance and traits of individual species and only modest effects at the community-level above and below ground. In contrast, nutrient addition experiments caused strong responses in primary producer and arthropod communities. This within-site synthesis enabled us to conclude how different environmental changes (experimental and ambient warming, nutrient addition, and environmental gradients) impact across ecological scales, which is challenging to achieve with across-site approaches.

Phenotypic plasticity can mask population genetic differentiation, reducing the predictability of trait-environment relationships. In short-lived plants, reproductive traits may be more genetically determined due to their direct impact on fitness, whereas vegetative traits may show higher plasticity to buffer short-term perturbations. Combining a multi-treatment greenhouse experiment with global field observations for the short-lived Plantago lanceolata, we 1) disentangled the genetic and plastic responses of functional traits to a set of environmental drivers and 2) assessed the utility of trait-environment relationshisps inferred from observational data for predicting genetic differentiation. Reproductive traits showed distinct genetic differentiation that was highly predictable from observational data, but only when correcting traits for differences in their (labile) biomass component. Vegetative traits showed higher plasticity and contrasting genetic and plastic responses, leading to unpredictable trait patterns. Our study suggests that genetic differentiation may be inferred from observational data only for the traits most closely related with fitness.

I Norge regnes flere varianter av edelløvskog som truet. På Østlandet finnes det gjengrodde jordbruks- og skoglandskap hvor skjøtselstiltak kan bidra til å gjenskape edelløvskogen. Formålet med denne artikkelen er å undersøke skogeieres erfaringer med og interesse for restaurering av edelløvskog, hva restaurering av edelløvskoger kan bety for lokalbefolkningen og hvordan lokale organisasjoner kan bidra til friluftsliv i områder med edelløvskog. Videre er formålet å gi et bilde av hvor godt dagens forvaltningssystemer og virkemiddelapparat er tilpasset restaurering av skog som er avhengig av skjøtsel for ivaretakelse av det biologiske mangfoldet. restoration, deciduous forest, policy instruments, attitudes Several types of temperate deciduous forest are threatened in Norway. For some of these forests, restoration through long-term and regular management will be important if biodiversity should be restored. The TransForest project established 13 field trials to carry out selective thinning to restore temperate deciduous forests. Based on qualitative data and document analyses this article analyses 1) forest owners' experiences, perspectives, and interest in restoration of these forests; 2) what outdoor recreation organizations think about restoration of these forests; and 3) whether current agricultural and environmental policy instruments are suited for supporting restoration of temperate deciduous forest that need regular management. Personal interviews were carried out with forest owners that had hosted the field trials, representatives from outdoor recreation organisations, and key informants from private and public organisations on policy and planning instruments. Our results show that forest owners and local outdoor recreation organisations value the thinning measures that have been carried out. The forest owners generally do not see any possibilities for net earnings from these measures and the representatives from the local outdoor recreation organisations emphasize that the public sector should bear the costs of restoration measures. Norwegian policy instruments for forests and agricultural land are, however, poorly fit for stimulating restoration measures that imply regular management in temperate deciduous forests.

Genetic differentiation and phenotypic plasticity jointly shape intraspecific trait variation, but their roles differ among traits. In short- lived plants, reproductive traits may be more genetically determined due to their impact on fitness, whereas vegetative traits may show higher plasticity to buffer short- term perturbations. Combining a multi- treatment greenhouse experiment with observational field data throughout the range of a widespread short- lived herb, Plantago lanceolata, we (1) disentangled genetic and plastic responses of functional traits to a set of environmental drivers and (2) assessed how genetic differentiation and plasticity shape observational trait– environment relationships. Reproductive traits showed distinct genetic differentiation that largely determined observational patterns, but only when correcting traits for differences in biomass. Vegetative traits showed higher plasticity and opposite genetic and plastic responses, masking the genetic component underlying field- observed trait variation. Our study suggests that genetic differentiation may be inferred from observational data only for the traits most closely related to fitness.

Recent forests may be an asset for green infrastructure and ecological restoration, but studies are needed of the variation in forest biodiversity among sites, and possible reasons for observed patterns. In boreonemoral Scandinavia, reforestation occurs on abandoned agricultural land, and we studied 27 such recent (40–80 years old) mixed forests with temperate deciduous trees and boreal trees including Norway spruce, and their communities of dead wood fungi and vascular plants. By analysing aerial photos from 1960 and 2017, we explored how species richness and composition within sites vary with historical and present tree cover, and separately spruce cover, at site scale (2 ha) and within the surroundings (12.5 ha). Tree cover, and the percentage spruce cover, had increased considerably from 1960 and 2017, while open areas had decreased accordingly, at both scales. We found no significant relationships between species richness of forest plants, or fungi on coarse woody debris, and tree cover at any scale. On the other hand, species richness of grassland plants, and fungi on fine woody debris, showed significant negative correlations with high tree cover, and thus the recent forests with the highest total species richness seem to occur in surroundings with lower tree cover, currently dominated by agriculture. The reason may be a correlation between richer soils and more agriculture; the area with the richest soil have been extensively cleared and cultivated, and therefore currently have lower tree cover and more fragmented forests. Furthermore, ordination analysis showed that several deciduous tree species were negatively correlated with tree cover, locally and in the surroundings, while the tree species preferring rich soil such as Fraxinus and Ulmus (and several associated fungal species), were positively correlated with spruce cover. A possible explanation is that spruce colonize well on abandoned grasslands and therefore tends to be associated with grassland plants and trees requiring the richer soils of these areas. We suggest that recent forests in boreonemoral areas could be used for instance for restoration of temperate deciduous woodland, especially in areas dominated by agriculture, but that recurrent management may be needed to avoid spruce domination. Forest restoration Reforestation Sprucification Temperate deciduous forest Vascular plants Dead wood

Recreational use of nature areas is increasing worldwide. All trail-based activities have a certain degradation effect on vegetation and soil, and conflicts between conservation values and recreation may occur. Controversy still exists regarding the relative impact of mountain bikers compared to hikers on trails. In this study, we manipulated the use intensity from hikers and mountain bikers on existing, natural-surfaced trails, and investigated effects of increased use and the relative importance of mountain biking on trail degradation. In two study sites, two trails were selected, one designated for hiking and one for biking. Passes were counted with TRAFx counters. The proportion of mountain bikers on the designated biking trails was on average 47%, and on the hiking trails 13%. Trail width and depth were recorded at permanently marked transects repeatedly throughout the growing season, and analyzed with linear mixed models as a function of number of passes, proportion of bikers and environmental conditions along the trail. Trail width, both the core trail without vegetation and the total area influenced by trampling and biking, showed on average small, but highly variable increases with enhanced use. Trail widening occurred particularly in moist parts, and trail width increased more when a larger proportion of the passes was mountain bikers. Trail depth did not change much throughout the study period, suggesting that the soils along the trails were already compacted and to a limited degree prone to soil movement and subsequent soil loss. Our study shows that on-trail use by hikers and mountain bikers have relatively limited overall effects in terms of trail widening and deepening, but that effects depend highly on environmental conditions; enhanced use of trails in wet areas is likely to result in greater trail degradation, and more so if a large proportion of the users are mountain bikers. Management and maintenance of trails, in terms of re-routing or trail surface hardening, could thus be necessary to avoid negative impacts of increased use. For such management actions to be successful, they need to be targeted towards the actual user groups and the natural conditions in the area. Recreation Trail degradation Hiking Mountain biking Alpine Forest

International audience; In climate change ecology, simplistic research approaches may yield unrealistically simplistic answers to often more complicated problems. In particular, the complexity of vegetation responses to global climate change begs a better understanding of the impacts of concomitant changes in several climatic drivers, how these impacts vary across different climatic contexts, and of the demographic processes underlying population changes. Using a replicated, factorial, whole‐community transplant experiment, we investigated regional variation in demographic responses of plant populations to increased temperature and/or precipitation. Across four perennial forb species and 12 sites, we found strong responses to both temperature and precipitation change. Changes in population growth rates were mainly due to changes in survival and clonality. In three of the four study species, the combined increase in temperature and precipitation reflected nonadditive, antagonistic interactions of the single climatic changes for population growth rate and survival, while the interactions were additive and synergistic for clonality. This disparity affects the persistence of genotypes, but also suggests that the mechanisms behind the responses of the vital rates differ. In addition, survival effects varied systematically with climatic context, with wetter and warmer + wetter transplants showing less positive or more negative responses at warmer sites. The detailed demographic approach yields important mechanistic insights into how concomitant changes in temperature and precipitation affect plants, which makes our results generalizable beyond the four study species. Our comprehensive study design illustrates the power of replicated field experiments in disentangling the complex relationships and patterns that govern climate change impacts across real‐world species and landscapes.

Habitat fragmentation resulting from anthropogenic land-use change may negatively affect both biodiversity and ecosystem structure and function. However, susceptibility to fragmentation varies between species and may be influenced by for instance specialization, functional traits and trophic level. We examined how total and specialist species richness, species composition and functional trait composition at two trophic levels (vascular plants and sap-feeding hoppers) vary with habitat fragmentation (patch size and connectivity) in dry calcareous grasslands in southeast Norway. We found that fragmentation affected plant and hopper species composition both totally and of habitat specialists, but with a net species loss only for the specialists, indicating greater susceptibility of specialized species. Reductions in patch size and increasing isolation negatively affected plant specialists with different sets of traits, effectively reducing the number of species with trait combinations suitable to persist in small and isolated patches. Fragmentation influenced trait composition of the total hopper community, but not of habitat specialists. A lesser degree of habitat association could explain why hoppers, despite belonging to a higher tropic level, seemed to be less susceptible to fragmentation than plants. Nonetheless, our study shows that habitat fragmentation affects both species richness, species composition and trait composition of plants and hoppers, indicating that fragmentation leads not only to a loss of species, but also alters dominance hierarchies and the functionality of grassland communities. Calcareous grasslands · Functional traits · Habitat fragmentation · Auchenorrhyncha · Vascular plants

Globally accelerating trends in societal development and human environmental impacts since the mid-twentieth century 1–7 are known as the Great Acceleration and have been discussed as a key indicator of the onset of the Anthropocene epoch 6 . While reports on ecological responses (for example, changes in species range or local extinctions) to the Great Acceleration are multiplying 8, 9 , it is unknown whether such biotic responses are undergoing a similar acceleration over time. This knowledge gap stems from the limited availability of time series data on biodiversity changes across large temporal and geographical extents. Here we use a dataset of repeated plant surveys from 302 mountain summits across Europe, spanning 145 years of observation, to assess the temporal trajectory of mountain biodiversity changes as a globally coherent imprint of the Anthropocene. We find a continent-wide acceleration in the rate of increase in plant species richness, with five times as much species enrichment between 2007 and 2016 as fifty years ago, between 1957 and 1966. This acceleration is strikingly synchronized with accelerated global warming and is not linked to alternative global change drivers. The accelerating increases in species richness on mountain summits across this broad spatial extent demonstrate that acceleration in climate-induced biotic change is occurring even in remote places on Earth, with potentially far-ranging consequences not only for biodiversity, but also for ecosystem functioning and services.

Background The stress-gradient hypothesis predicts a shift from facilitative to competitive plant interactions with decreasing abiotic stress. This has been supported by studies along elevation and temperature gradients, but also challenged by the hypothesis of a facilitation collapse at extremely harsh sites. Although facilitation is known to be important in primary succession, few studies have examined these hypotheses along primary succession gradients. Aim To examine whether there is a relationship between the presence of the circumpolar cushion plant Silene acaulis and other species, and if so, whether there is a shift between positive and negative interactions along a primary succession gradient in a glacier foreland. Location Finse, southern Norway. Methods We examined the performance of the common alpine forb Bistorta vivipara, species richness of vascular plants, bryophytes and lichens, and the number of seedlings and fertile vascular plants in S. acaulis cushions, and control plots without S. acaulis, along a succession gradient with increasing distance from a glacier front, and thus decreasing abiotic stress. To examine if S. acaulis cushions modify the abiotic environment, we recorded soil temperature, moisture, organic content and pH in cushions and control plots. Results B. vivipara performed better, as shown by bigger leaves in S. acaulis cushions compared to control plots in the harshest part of the gradient close to the glacier. There were few differences in B. vivipara performance between cushion and control plots in the more benign environment further away from the glacier. This suggests a shift from facilitative to mainly neutral interactions by S. acaulis on the performance of B. vivipara with decreasing abiotic stress. A trend, although not significant, of higher vascular species richness and fertility inside S. acaulis cushions along the whole gradient, suggests that S. acaulis also facilitates community-level species richness. The causal mechanism of this facilitation is likely that the cushions buffer extreme temperatures. Conclusions Our results support the stress-gradient hypothesis for the relationship between the cushion plant S. acaulis and the performance of a single species along a primary succession gradient in a glacier foreland. S. acaulis also tended to increase vascular plant species richness and fertility regardless of stress level along the gradient, suggesting facilitation at the community level. We found no collapse of facilitation at the most stressful end of the gradient in this alpine glacier foreland.

© 2020 The Authors. Global change experiments such as experimental warming and nutrient addition strongly affect the structure and functioning of high latitude and altitude ecosystems. However, it is often unknown to what extend such effects are permanent or whether changes persist after environmental conditions return to pre-treatment levels. In this study, we assess the legacy effects of temperature manipulation and nutrient addition experiments on alpine soil micro-arthropod (i.e., Collembola and Oribatida) communities nine years after the treatments were discontinued. Treatment effects on the vegetation were still detectable six years after cessation, although grazing increased the recovery rate. Because micro-arthropods are often closely associated with vegetation, we expected to find that treatment effects on Collembola and Oribatida abundance and species composition persisted to date, reflecting plant community dynamics. Also, we expected large-bodied, drought-resistant Collembola species that live on top of the soil to show less strong legacy effects. We did not find legacy effects of environmental treatments on Collembola and Mesostigmata in terms of abundance. However, we found persistent changes in community composition of Collembola and Oribatida, suggesting treatment effects persist to date. The generalist Folsomia quadrioculata was the most responsive Collembola species to initial treatments, most likely due to its variable life-history strategy. Although its abundance recovered, F. quadrioculata remained dominant in Collembola communities after cessation of the treatments. Grazing affected community composition of both Collembola and Oribatida, but we did not find grazing to reduce legacy effects on micro-arthropod as it did for vegetation. We therefore conclude that the environmental treatments had only temporary effects on micro-arthropods in terms of overall abundance, but that effects on individual species and therefore species composition may be long-lasting and less predictable. The study was designed by Johan Asplund, Juha M. Alatalo, and Kari Klanderud. Field work was performed by Ruben Erik Roos, Johan Asplund, Kari Klanderud, and Tone Birkemoe. Peter Ľuptáčik and Natália Raschmanová identified soil micro‐arthropods for 2016. Statistical analyses were performed by Ruben Erik Roos and Siri Lie Olsen. All co‐authors contributed to manuscript revisions and agree with the final version. This study was funded by Carl Tryggers stiftelse för vetenskaplig forskning through a grant to Juha M. Alatalo and a grant from the Research Council of Norway (249902) to Johan Asplund. We thank Sigmund Hågvar for sharing his original data, comments and feedback, Hans Cornelissen and Stef Bokhorst for useful discussions, and Matty Berg for sharing data from his personal Collembola database. Mari Steinert, Ross Wetherbee, Mahdieh Tourani, and Richard Bischof were of great help for discussions on the statistical analyses. We thank the Finse Alpine Research Center and Erika Leslie for hospitality during fieldwork and Kristel van Zuijlen for assistance in the field.

Globally, boreal forests cover 33 percent of Earth's forested area, constitute the largest terrestrial carbon source, and house an important biodiversity of forest-dependent species, many of which are saproxylic taxa reliant on a wide variety of dead wood. This dead wood is most prevalent in old-growth forest, yet intensive management means that little old growth is left, and the remaining forests rarely attain the necessary age and structure to resemble these original forests. There is increasing recognition, however, that forests that have not been subjected to modern, stand-replacing harvest methods (like clear-cutting), and in which management activities are no longer occurring, may be able to provide habitat similar to old-growth forest for many species (older mean age, higher deadwood volumes, and more age-class heterogeneity). These are called ‘near-natural’ forests. We use linear mixed models and redundancy analysis (RDA) to compare beetle species richness and community composition using a large, mixed data set, containing more than one third of all beetle species known from Norway, from window trap records in three types of forest: intensively managed mature stands, recent clear-cuts, and ‘near-natural forests’. Even though location, study substrate and other sampling details vary substantially between sites, the signal from management still comes out as a significant factor explaining the patterns on beetle diversity. We find that species richness of saproxylic, natural-forest indicator, and red-listed beetle species is higher in both near-natural forests and recent clear-cuts than in managed mature forests. Community composition also differs significantly between the three forest types, and these differences are correlated with forest age and volume at the landscape (1 km radius) level. These findings provide support for the idea that near-natural forests provide habitats that are distinct from those in managed forests and which are important for species of conservation concern. Clear-cuts briefly harbor some of these same species, probably due to the sun-exposed coarse woody debris (CWD) that is available immediately after felling, but this effect is transient. Conservation of existing near-natural forests, many of which are currently without legal protection, should therefore be prioritized.

Significance We found that long-distance dispersal and repeated introductions by humans have shaped adaptive potential in a globally distributed invasive species. Some plant species, therefore, do not need strong demographic changes to overcome environmental constraints that exist in the native range; simply mixing genetic stock from multiple populations can provide an adaptive advantage. This work highlights the value of preventing future introduction events for problematic invasive species, even if the species already exists in an area., When plants establish outside their native range, their ability to adapt to the new environment is influenced by both demography and dispersal. However, the relative importance of these two factors is poorly understood. To quantify the influence of demography and dispersal on patterns of genetic diversity underlying adaptation, we used data from a globally distributed demographic research network comprising 35 native and 18 nonnative populations of Plantago lanceolata. Species-specific simulation experiments showed that dispersal would dilute demographic influences on genetic diversity at local scales. Populations in the native European range had strong spatial genetic structure associated with geographic distance and precipitation seasonality. In contrast, nonnative populations had weaker spatial genetic structure that was not associated with environmental gradients but with higher within-population genetic diversity. Our findings show that dispersal caused by repeated, long-distance, human-mediated introductions has allowed invasive plant populations to overcome environmental constraints on genetic diversity, even without strong demographic changes. The impact of invasive plants may, therefore, increase with repeated introductions, highlighting the need to constrain future introductions of species even if they already exist in an area.

Biotic interactions are often ignored in assessments of climate change impacts. However, climate-related changes in species interactions, often mediated through increased dominance of certain species or functional groups, may have important implications for how species respond to climate warming and altered precipitation patterns. We examined how a dominant plant functional group affected the population dynamics of four co-occurring forb species by experimentally removing graminoids in seminatural grasslands. Specifically, we explored how the interaction between dominants and subordinates varied with climate by replicating the removal experiment across a climate grid consisting of 12 field sites spanning broad-scale temperature and precipitation gradients in southern Norway. Biotic interactions affected population growth rates of all study species, and the net outcome of interactions between dominants and subordinates switched from facilitation to competition with increasing temperature along the temperature gradient. The impacts of competitive interactions on subordinates in the warmer sites could primarily be attributed to reduced plant survival. Whereas the response to dominant removal varied with temperature, there was no overall effect of precipitation on the balance between competition and facilitation. Our findings suggest that global warming may increase the relative importance of competitive interactions in seminatural grasslands across a wide range of precipitation levels, thereby favouring highly competitive dominant species over subordinate species. As a result, seminatural grasslands may become increasingly dependent on disturbance (i.e. traditional management such as grazing and mowing) to maintain viable populations of subordinate species and thereby biodiversity under future climates. Our study highlights the importance of population-level studies replicated under different climatic conditions for understanding the underlying mechanisms of climate change impacts on plants.

Seedling recruitment is a critical life history stage for trees, and successful recruitment is tightly linked to both abiotic factors and biotic interactions. In order to better understand how tree species’ distributions may change in response to anticipated climate change, more knowledge of the effects of complex climate and biotic interactions is needed. We conducted a seed-sowing experiment to investigate how temperature, precipitation and biotic interactions impact recruitment of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) seedlings in southern Norway. Seeds were sown into intact vegetation and experimentally created gaps. To study the combined effects of temperature and precipitation, the experiment was replicated across 12 sites, spanning a natural climate gradient from boreal to alpine and from sub-continental to oceanic. Seedling emergence and survival were assessed 12 and 16 months after sowing, respectively, and aboveground biomass and height were determined at the end of the experiment. Interestingly, very few seedlings were detected in the boreal sites, and the highest number of seedlings emerged and established in the alpine sites, indicating that low temperature did not limit seedling recruitment. Site precipitation had an overall positive effect on seedling recruitment, especially at intermediate precipitation levels. Seedling emergence, establishment and biomass were higher in gap plots compared to intact vegetation at all temperature levels. These results suggest that biotic interactions in the form of competition may be more important than temperature as a limiting factor for tree seedling recruitment in the sub- and low-alpine zone of southern Norway. acceptedVersion

Summary Global change, such as climate warming and nitrogen deposition, has been predicted to induce non-reversible regime shifts in natural ecosystems. However, we lack knowledge of the potential for recovery from global change perturbations and factors influencing the recovery rate. We examined the recovery of an alpine plant community from a combined warming and nutrient addition experiment, which initially caused profound changes in plant community composition and diversity. We also examined whether the recovery process was affected by herbivory, as the presence of herbivores has been shown to modify the response of plant communities to global change. Many aspects of the alpine plant community had not recovered from experimental warming and nutrient addition 6 years after cessation of the treatments. A persistent shift in vascular plant species composition seemed to inhibit recovery and maintain a community dominated by highly competitive grasses at the expense of the previously dominating dwarf shrub Dryas octopetala, lichens and bryophytes. The exclusion of herbivores decreased the community recovery rate by maintaining unfavourable conditions for lichens and bryophytes. Synthesis. Our findings suggest that a shift in dominance hierarchies in arctic and alpine plant communities due to global change is not readily reversible. Herbivory may, however, facilitate plant community recovery.

Low nitrogen (N) supply is a limiting factor for plant growth in most terrestrial ecosystems. N-fixing legumes therefore have the potential to facilitate surrounding vegetation by increasing soil N levels. This effect should be especially pronounced in low-productivity habitats where ambient soil N levels are low, such as in alpine areas. We examined whether plant species composition, community diversity measures, and soil N levels differed with and without the presence of two alpine legumes, Oxytropis lapponica (Wahlenb.) Gay and Astragalus alpinus L., in a Dryas octopetala heath at Finse, Norway. Species composition and richness differed between plots with and without Oxytropis in one of two study sites, as other plant species were positively associated with the legume. None of the measured community properties differed between plots with and without the presence of Astragalus. The contrasting influence of the two legume species corresponds to our findings of higher soil N levels below Oxytropi...

Th e determinants of local species richness in plant communities have been the subject of much debate. Is species richness the result of stochastic events such as dispersal processes, or do local environmental fi lters sort species into communities according to their ecological niches? Recent studies suggest that these two processes simultaneously limit species richness, although their relative importance may vary in space and time. Understanding the limiting factors for species richness is especially important in light of the ongoing global warming, as new species establish in resident plant communities as a result of climate-driven migration. We examined the relative importance of dispersal and environmental fi ltering during seedling recruitment and plant establishment in an alpine plant community subjected to seed addition and long-term experimental warming. Seed addition increased species richness during the seedling recruitment stage, but this initial increase was cancelled out by a corresponding decrease in species richness during plant establishment, suggesting that environmental fi lters limit local species richness in the long term. While initial recruitment success of the sown species was related to both abiotic and biotic factors, long-term establishment was controlled mainly by biotic factors, indicating an increase in the relative importance of biotic interactions once plants have germinated in a microhabitat with favourable abiotic conditions. Th e relative importance of biotic interactions also seemed to increase with experimental warming, suggesting that increased competition within the resident vegetation may decrease community invasibility as the climate warms.

We describe changes in vascular plant richness on 13 high mountain summits based on a historical study performed approximately 40 years ago. A summit is defined as the uppermost 30 m of the mountain tops. The altitudes of the summits range from 1512 to 1814 m. Data from neighboring climatologic stations showed higher mean values for July temperature (+0.7 °C) and January temperature (+1.5 °C), and mean annual precipitation had increased from 714 to 764.7 mm (7.1%) for the period from 1970 until 2009 compared with average data for the normal period (1961–1990). The total “top flora” had during this period increased by 19 taxa. On average, the increase in taxa richness was 18.9 ± 8.4 per summit, representing an average increase of 90.2%. Woody species had an average upward movement of 7.3 m during the study period. The ongoing upward shift of common, ubiquitous alpine species has resulted in a floristic homogenization of the mountain summits, and thus increasing α-diversity was accompanied by decre...

International audience; Most range shift predictions focus on the dispersal phase of the colonization process. Since moving populations experience increasingly dissimilar non-climatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in non-local sites. We assess the intraspecific variation in growth responses to non-local soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600 km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently 'colder' soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate-change driven plant movements by affecting growth of non-local migrants, a mechanism which should be integrated in predictions of future range shifts.

Økologisk restaurering handler om å gjenopprette økosystemer som på ulike måter har blitt forringet eller ødelagt. I skogene i Europa har særlig planting av gran i løvskoger en stor påvirkning på skogøkosystemene. I Norge har vi en særlig stor variasjon av boreale løvskoger, inkludert noen særlig verdifulle typer, og dette medfører et ekstra ansvar. I Junkerdalsura naturreservat nord for Saltfjellet i Nordland finnes store mengder rike fjellbjørkeskogutforminger. En trussel mot disse stedegne bjørkeskogene er spredningen av gran picea abies, som ble plantet i deler av reservatet mellom 1920- og 1960-tallet. Restaureringstiltak ble derfor igangsatt for å gjenopprette den stedegne fjellbjørkeskogen med tilhørende vegetasjon. Hogst med uttak av tømmer ble gjennomført i to granplantefelt i 2018 og 2019, og i 2021 ble et granplantefelt veteranisert, som innebærer en svekking av trærne som fremskynder en aldringsprosess og død. I 2022 undersøkte jeg effekten av disse tiltakene på vegetasjon. Parameterne for å evaluere effekten var artsrikdom, artssammensetning og dekning av ulike vegetasjonssjikt. Jeg fant at lukket hogst i et nokså fuktig/kildevannspåvirket område, med noe gjenværende kronedekke av bjørk, resulterte i en artssammensetning og dekning av arter i feltsjiktet tilsvarende den omkringliggende bjørkeskogen allerede tre år etter restaureringstiltaket. En mer omfattende hogst i et noe tørrere område førte til et stort oppslag av pionérarter hovedsakelig dominert av bringebær fire år etter restaureringstiltaket. Artsrikdommen nådde ikke opp til nivået til bjørkeskogen i noen av områdene. Veteraniseringstiltakene hadde medført et noe lavere kronedekke ett år etter tiltak, men resulterte ikke i endringer i hverken artsrikdom, artssammensetning eller dekning av planter i feltsjiktet. Resultatene viser at gjenopprettelse av artssammensetning i bjørkeskog kan gå fort, dersom forholdene ligger til rette for det. Hogstintensitet, kronedekning og kildevannspåvirkning kan dermed være viktige påvirkningsfaktorer i gjenopprettelsesprosessen etter restaurering i boreale fjellbjørkeskoger. Dette studiet i Junkerdalsura er den eneste kjente studien av restaurering av boreal fjellbjørkeskog i Norden, og er et viktig bidrag til kunnskapsbasen for disse skogene. Ecological restoration aims to aid the recovery of ecosystems that have been degraded or destroyed in various ways. In the forests of Europe, the planting of spruce in deciduous forests has had a significant impact on forest ecosystems. In Norway, there is a particularly large variation of boreal deciduous forests, including some particularly valuable types, which entails an extra responsibility. In the Junkerdalsura Nature Reserve north of Saltfjellet in Nordland, there are large amounts of species rich mountain birch forest formations. A threat to these indigenous birch forests is the spread of Norway spruce Picea abies, which was planted in parts of the reserve between the 1920s and 1960s. Restoration measures were therefore initiated to restore the indigenous mountain birch forest with associated vegetation. Logging with timber extraction was carried out in two spruce plantations in 2018 and 2019, and in 2021, a spruce plantation was veteranized, a process which weakens the trees and accelerates an aging process and death. In 2022, I investigated the effect of these measures on vegetation. The parameters for evaluating the effect were species richness, species composition, and the cover of different parts of the vegetation. I found that partial logging in an area influenced by spring-water, with some remaining canopy cover of birch, resulted in a species composition and coverage of species in the field layer equivalent to the surrounding birch forest already three years after the restoration measure. A more extensive logging in a somewhat drier area resulted in a large outbreak of pioneer species mainly dominated by raspberry four years after the restoration measure. Species richness did not reach the level of the birch forest in any of the areas. The veteranization measures had resulted in slightly lower canopy cover one year after the measure, but did not result in any changes in either species richness, species composition, or cover of plants in the field layer. The results show that restoring species composition in birch forest can be fast if conditions are right. Canopy cover, logging intensity, remaining canopy cover, and spring water influence can therefore be important factors influencing the recovery process after restoration in boreal mountain birch forests. This study in Junkerdalsura is the only known study of restoration of boreal mountain birch forests in the Nordic countries and is an important contribution to the knowledge base for these forests.

Død ved spiller en essensiell rolle i skogøkosystemer ved å bidra med økosystemfunksjoner som karbonlagring og næringsstoff-sirkulering, i tillegg til å være en fundamental ressurs for biodiversitet i skog. Vedlevende biller er en av de største artsgruppene som lever i tilknytning til død ved, og det er et svært viktig substrat for mange av disse artene, som blant annet bidrar med nedbrytning av ved og næringsstoffsirkulering. Intensivt skogbruk har ført til en mangel på død ved i produksjonsskoger, som har en vesentlig negativ effekt på mange vedlevende arter. Junkerdalsura naturreservat i Nordland omfatter et område med rik flora og fauna, og har en av de største forekomstene av kalkbjørkeskog i Norden. Naturreservatet ligger utenfor granas naturlige utbredelsesområde, men det ble i løpet av 1900-tallet plantet flere granfelt i dette området. Disse granfeltene utgjør i dag en trussel for mange av de stedegne artene, på grunn av spredning og etablering av grantrær utenfor feltene. Det er derfor ønskelig å restaurere granfeltene tilbake til den naturlige tilstanden før plantingen, som er den rike bjørkeskogen som vokser i området. Fra 2017 til 2021 ble det derfor utført flere restaureringstiltak for å fjerne granfeltene. I et av granfeltene bestod disse tiltakene av felling og veteranisering av grantrærne, der veteraniseringen fører til at trærne svekkes og dør over en lenger periode, og dermed bidrar med tilførsel av død ved over tid. Det var derfor interessant å undersøke om død ved-tilførselen gjennom disse restaureringstiltakene kunne ha en verdi for vedlevende biller, samtidig som granfeltet restaureres til bjørkeskog, til tross for at grana er uønsket i området. Jeg brukte vindusfeller for å sammenligne billefaunaen i granfeltet med restaureringstiltak, med et kontrollområde i granfeltet uten restaureringstiltak og omkringliggende bjørkeskog. Ett år etter at restaureringen ble utført, viste resultatene at det var en signifikant økning i artsrikdom og abundans hos de vedlevende artene, og spesielt for underkategorien bartre-spesialister, i granfeltet med tiltakene, sammenlignet med granfeltet uten tiltak. Mengde død ved hadde en signifikant positiv effekt på abundans og artssammensetningen av vedlevende biller, men ikke på artsrikdom. Det var distinkte forskjeller i billenes artssammensetning mellom granfeltet og bjørkeskogen, og artssammensetningen var fremdeles lik i delene av granfeltet med og uten restaureringstiltak, hvilket reflekterer det tidlige stadiet av restaureringsprosessen. Studiet viser at fjerning av uønskede granplantefelt ved felling og veteranisering uten tømmeruttak, i tillegg til å være arbeids- og kostnadsbesparende ettersom man slipper å frakte den døde veden ut av området, også skaper en ressurs for mange vedlevende biller.

Kalkfuruskogar husar eit særleg rikt artsmangfald med mange habitatspesifikke og sjeldne artar, og er difor ein spesielt viktig naturtype i forvaltningssamanheng. Orkidéen flueblom Ophrys insectifera har si hovudutbreiing i kalkfuruskog. Det er kjend at arten er lyskrevjande, og difor har hatt tilbakegang i tidlegare beiteskogar som gror igjen etter opphøyrt hevd. I dette studiet undersøkast effekten av skjøtselstiltak på flueblom og vegetasjonssamansetjing i tre verneområde på Austlandet, med kalkfuruskog som har vore påverka av gjengroing: Røsskleiva naturreservat, Haugene naturreservat og Langøya landskapsvernområde. Skjøtselseffektar vart undersøkt gjennom registrering av antal flueblom, vitalitetsindikatorar for flueblom, vegetasjonsdekke, artsrikdom og artssamansetjing ved hjelp av ruteanalysar som vart utført i blomstringssesongen i 2022. Forskjellar vart testa gjennom samanlikning av data frå 2022 med data frå tidlegare kartleggingar for Røsskleiva og Haugene, og gjennom samanlikning av eit skjøtta og eit uskjøtta område på Langøya i 2022. Det vart påvist ein stor nedgang i antal flueblom i Røsskleiva frå 1984 til 2017. Skjøtselstiltak vart implementert i 2017, men antalet flueblom hadde framleis ikkje auka i 2022. Det vart observert ein nedgang i busksjiktdekning etter utført skjøtsel, men tresjiktet var framleis tett og dekningsgraden i felt- og botnsjiktet var ikkje signifikant forskjellig mellom 2017 og 2022. Skjøtselstiltaka hadde ikkje resultert i ein høgare artsrikdom eller større innslag av lyskrevjande artar, sjølv om artssamansetjinga var ulik mellom åra. I Haugene var det òg ein stor nedgang i antal flueblom mellom 1984 og 2022, sjølv om skjøtselstiltak vart utført frå 2010. Dekningsgraden i tre- og busk- og botnsjiktet var lågare i 2022 enn i 1984, men feltsjiktsdekninga var uendra. Artsrikdomen og innslaget av lyskrevjande artar var ikkje blitt større, sjølv om artssamansetjinga var noko endra. Mellom eit område på Langøya som var uskjøtta eit område som vart skjøtta frå 2016/2017, var det ikkje forskjell i antal flueblom i 2022, men flueblomen i det skjøtta området hadde fleire blad, som kan indikere større grad av vitalitet. Vegetasjonssamansetjinga skilde seg heller ikkje signifikant mellom dei to områda, men det var tendensar til lågare busksjiktdekning i det skjøtta området. I sum vart det påvist få positive effektar av skjøtsel på flueblom og andre lyskrevjande artar i dei tre studieområda, og flueblombestanden har hatt ein nedgang i to av dei. Tregleik i respons, både etter gjengroing og skjøtsel, kan potensielt spele ei stor rolle for kor synlege effektane av skjøtsel var per 2022. I tillegg kan antalet blomstrande flueblomindivid fluktuere mykje mellom år. Det trengs vidare analysar for å fange opp skjøtselseffekten i desse områda, slik at den nedgangen i flueblombestanden som er sett kan motverkast. Calcareous pine forests harbor a rich species diversity with many habitat-specific and rare species, and are therefore particularly important in management context. The fly orchid Ophrys insectifera has its main distribution in calcareous pine forests. The species is somewhat light- demanding, and has declined in previously grazed forests with overgrowth after cessation of usage. This study examines the effects of management measures on fly orchid and vegetation composition in three nature conservation areas in Norway with calcareous pine forests affected by overgrowth: Røsskleiva nature reserve, Haugene nature reserve, and Langøya landscape protection area. The effects of management were investigated through registration of the number of fly orchids and their features, vegetation coverage and species richness- and composition, performing quadrat analyses. Differences were tested comparing data from 2022 to data from previous surveys for Røsskleiva and Haugene, and comparing an area treated from 2016/2017 to an untreated area on Langøya. A strong decline in the number of fly orchids was detected in Røsskleiva from 1984 to 2017. The population had still not increased by 2022, although management measures were implemented in 2017. The shrub layer coverage decreased between 2017 and 2022, but the tree layer was still dense, and the herb- and moss layer coverage was not significantly different. Management measures implemented in 2017 had not led to an increased number of fly orchids in 2022, nor a higher species richness or greater presence of light-demanding species, although there was a difference in species composition. It was also detected a significant decline in the number of fly orchids in Haugene between 1984 and 2022, despite the management measures in 2010. The coverage of the tree, shrub- and moss layer had declined between 1984 and 2022, but the herb layer coverage was unaffected. The species richness and presence of light-demanding species had not increased, even though the species composition was slightly changed. On Langøya, there was no difference in the number of fly orchids between the two areas in 2022. However, the orchids in the treated area had more leaves, which could indicate increased vitality. The vegetation composition did not differ significantly between the two areas, but there were tendencies towards less shrubs in the treated area. In total, there were detected few positive effects of management on the fly orchid and other light-demanding species in the study areas, and the fly orchid population had decreased in two of them. Delay in response following both overgrowth and management, as well as yearly fluctuations, probably plays an important role for the visibility of management effects as of 2022. There will be needed further analyses to detect the effects of management in these areas, to further counteract the decrease in the fly orchid population that has been observed.

1. The grim fact is that biodiversity in ecosystems across the globe are rapidly declining due to anthropogenic activities. On the other hand, focus on actions that may halt this loss is on the rise. Ecological restoration is frequently used as a management tool to increase the quality of degraded habitats. Management actions used in ecological restoration are numerous, though invasive plant removal is the most common target. However, due to lack of documentation, there is still little knowledge of what the outcome from management actions are, and this presents a global knowledge gap in most of the earth’s ecosystems. 2. In this thesis I have investigated how monitoring methods can be used to detect effects from management actions in localities of dry calcareous grassland, in the inner Oslofjord region, Norway. I have through four monitoring methods analyzed difference in locality condition and biodiversity between ten managed- and ten unmanaged localities. In addition, I also visited four localities that underwent first-time management actions summer of 2022. 3. The four different monitoring methods (NatStat, NiN, calcareous grassland reduced, and calcareous grassland complete) vary in the level of detail and scale variables are estimated. Two of the methods detected significant results in locality condition; higher abundance of invasive species in the unmanaged localities. Further significant results were found in biodiversity; one method detected higher richness of habitat-specific species in the managed localities and another method found the same for red listed species. 4. Results from this thesis points to the importance of adapting scale of sampling to type of effect wished to study. Both number- and size of sampling plots influence the result. Limiting monitoring of effects to variables management actions have targeted and doing so in a practical spatial scale, may not only provide more useable data for management, but also reduce the financial costs and contribute to sustainable monitoring of effect programs. Closing the gap between scientific research and practical management actions, may provide a key solution to increase documentation of management work and effects from such actions.