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1. There is a growing recognition that functional measures of diversity, based on quantification of functionally important species traits, are useful for explaining variation in ecosystem processes. However, the mechanisms linking functional diversity to different processes remain poorly understood, hindering development of a predictive framework for ecosystem functioning based on species traits. 2. The current understanding of how the functional traits of aquatic plants (macrophytes) affect nitrogen (N) cycling by regulating microbial communities and their activity in freshwater habitats is particularly limited. Denitrifying bacteria are typically associated with the roots of both aquatic and terrestrial plants and denitrification is the main cause of loss of N from ecosystems. Disentangling the interplay between plants and microbial denitrifiers is key to understanding variation in rates of denitrification from local to landscape scales. 3. In a mesocosm experiment, we varied the species richness (monocultures or two-species mixtures) and composition of macrophytes. We quantified effects of both macrophyte functional diversity, quantified as functional trait dissimilarity, and functional trait composition, quantified as community weighted mean trait values, on N removal in wetlands. We used structural equation modelling to disentangle the direct and indirect influences of traits on N accumulation in plant biomass, denitrification activity and abundance of key bacterial denitrification genes (nirS and nirK). 4. Both functional diversity and functional trait composition regulated N removal, explaining 70%–94% variation in the underlying ecosystem processes. Increased macrophyte functional diversity increased plant N accumulation, and indirectly enhanced denitrification by increasing denitrification gene abundance. Among traits, greater plant relative growth rates, specific leaf area and above-ground biomass increased plant N accumulation. Denitrification activity increased with increasing below-ground biomass but decreased with increasing root diameter. 5. These findings improve our understanding of N removal in freshwater wetlands dominated by macrophytes, and have broad ecological implications for wetland management targeting enhanced ecosystem services. Our results highlight the potential for optimizing denitrification and plant N accumulation in wetlands and thereby improving water purification by increasing macrophyte functional diversity and ensuring the presence of key traits in macrophyte assemblages. biodiversity, denitrification, ecosystem functioning, ecosystem service, functional diversity, functional traits, macrophytes, plant uptake

Impact or risk assessments of alien species can use qualitative criteria (such as verbally described categories) or quantitative criteria (numerically defined threshold values of empirically measurable quantities). According to a common misconception, the use of qualitative criteria in invasion biology is justified by uncertainty in the available data. Yet qualitative criteria have the effect of increasing uncertainty. In contrast, assessments using quantitative criteria are testable, transparent, highly repeatable and comparable. Most of these characteristics do not even depend on the availability of numerical data. Although quantitative criteria do not necessarily make assessments correct, they do make them correctable, which is the benchmark of science.

Optimization of clutch size and timing of reproduction have substantial effects on lifetime reproductive success in vertebrates, and both individual quality and environmental variation may impact life history strategies. We tested hypotheses related to maternal investment and timing of reproduction, using 17 years (1978–1994) of individual-based life history data on willow ptarmigan ( Lagopus l. lagopus , n = 290 breeding females with n = 319 breeding attempts) in central Norway. We analysed whether climatic variation and individual state variables (age and body mass) affected the number of offspring and timing of reproduction, and individual repeatability in strategies. The results suggest that willow ptarmigan share a common optimal clutch size that is largely independent of measured individual states. While we found no clear direct weather effects on clutch size, higher spring temperatures advanced onset of breeding, and early breeding was followed by an increased number of offspring. Warmer springs were positively related to maternal mass, and mass interacted with clutch size in production of hatchlings. Finally, clutch size and timing of reproduction were highly repeatable within individuals, indicating that individual quality guided trade-offs in reproductive effort. Our results demonstrate how climatic forcing and individual heterogeneity in combination influenced life history traits in a resident montane keystone species.

Most European forests are used for timber production. Given the limited extent of unmanaged (and especially primary) forests, it is essential to include commercial forests in the conservation of forest biodiversity. In order to develop ecologically sustainable forest management practices, it is important to understand the management impacts on forest-dwelling organisms. Experiments allow testing the effects of alternative management strategies, and monitoring of multiple taxa informs us on the response range across forest-dwelling organisms. To provide a representative picture of the currently available information, metadata on 28 multi-taxa forest management experiments were collected from 14 European countries. We demonstrate the potential of compiling these experiments in a single network to upscale results from the local to continental level and indicate directions for future research. Among the different forest types, temperate deciduous beech and oak-dominated forests are the best represented in the multi-taxa manage ment experiments. Of all the experimental treatments, innovative ways of traditional manage ment techniques (e.g., gap cutting and thinning) and conservation-oriented interventions (e.g., microhabitat enrichment) provide the best opportunity for large-scale analyses. Regarding the organism groups, woody regeneration, herbs, fungi, beetles, bryophytes, birds and lichens offer the largest potential for addressing management–biodiversity relationships at the European level. We identified knowledge gaps regarding boreal, hemiboreal and broadleaved evergreen forests, the treatments of large herbivore exclusion, prescribed burning and forest floor or water ma nipulations, and the monitoring of soil-dwelling organisms and some vertebrate classes, e.g., amphibians, reptiles and mammals. To improve multi-site comparisons, design of future experi ments should be fitted to the set-up of the ongoing projects and standardised biodiversity sam pling is suggested. However, the network described here opens the way to learn lessons on the impact on forest biodiversity of different management techniques at the continental level, and thus, supports biodiversity conservation in managed forests.

Citizen science and automated collection methods increasinglydepend on image recognition to provide the amountsof observational data research and management needs.Recognition models, meanwhile, also require large amounts ofdata from these sources, creating a feedback loop between themethods and tools. Species that are harder to recognize, bothfor humans and machine learning algorithms, are likely to beunder-reported, and thus be less prevalent in the trainingdata. As a result, the feedback loop may hamper trainingmostly for species that already pose the greatest challenge. Inthis study, we trained recognition models for various taxa, andfound evidence for a‘recognizability bias’, where species thatare more readily identified by humans and recognitionmodels alike are more prevalent in the available image data.This pattern is present across multiple taxa, and does notappear to relate to differences in picture quality, biologicaltraits or data collection metrics other than recognizability. Thishas implications for the expected performance of futuremodels trained with more data, including such challenging species. citizen science, image recognition, machinelearning, recognizability, artificial intelligence/environmental science/ecology, Ecology, conservation and global change biology

The pace of Holocene vegetation change Although much is known about the rapid environmental changes that have occurred since the Industrial Revolution, the patterns of change over the preceding millennia have been only patchily understood. Using a global set of >1100 fossil pollen records, Mottl et al. explored the rates of vegetation change over the past 18,000 years (see the Perspective by Overpeck and Breshears). The authors show that the rates of change accelerated markedly during the Late Holocene (∼4.6 to 2.9 thousand years ago), even more rapidly than the climate-driven vegetation changes associated with the end of the last glacial period. In addition, the Late Holocene acceleration began for terrestrial communities as a whole, suggesting that the acceleration in turnover over the past two centuries is the tip of a deeper trend. Science , abg1685, this issue p. 860 ; see also abi9902, p. 786

1. Researchers in ecology and evolutionary biology are increasingly dependent on computational code to conduct research. Hence, the use of efficient methods to share, reproduce, and collaborate on code as well as document research is fundamental. GitHub is an online, cloud-based service that can help researchers track, organize, discuss, share, and collaborate on software and other materials related to research production, including data, code for analyses, and protocols. Despite these benefits, the use of GitHub in ecology and evolution is not widespread. 2. To help researchers in ecology and evolution adopt useful features from GitHub to improve their research workflows, we review 12 practical ways to use the platform. 3. We outline features ranging from low to high technical difficulty, including storing code, managing projects, coding collaboratively, conducting peer review, writing a manuscript, and using automated and continuous integration to streamline analyses. Given that members of a research team may have different technical skills and responsibilities, we describe how the optimal use of GitHub features may vary among members of a research collaboration. 4. As more ecologists and evolutionary biologists establish their workflows using GitHub, the field can continue to push the boundaries of collaborative, transparent, and open research. collaboration, data management, ecoinformatics, GitHub, open science, project management, reproducible research, version control

1. Long-term metapopulation persistence is mediated by the dynamics of colonization and extinction. To understand and predict future species occupancy in changing landscapes, we must account for the dynamic rates that shape the occupancy and disentangle their dependence on environmental conditions. Specialist and generalist species may differ in their dynamics in systematic ways. 2. Using an extensive, large-scale repeat survey dataset for wood-decaying fungi, we fitted dynamic metapopulation models for ten species, ranging from generalists to specialists with differing resource requirements. We first estimated base rates of colonization and extinction and tested their relationships to species' degree of specialization. We then tested for effects of local and landscape scale variables on the colonization and extinction rates. Finally, using the fitted models and a scenario of future forest development we projected future colonization–extinction dynamics over 100 years to test for differences in species occupancies between production stands and set-aside stands. 3. Our study revealed a striking pattern of decreasing colonization rates with increasing degree of specialization across species, along with concomitantly increasing extinction rates. Strong sensitivity of colonization probabilities to local habitat quality (dead wood volume and stand age) in specialist but not generalist species constrained the regional occupancy of specialists, especially in production forest. We found evidence for short-range dispersal limitation in two specialists, but no effect of our measure for landscape-scale connectivity on colonization rates. Simulations of future metapopulation dynamics resulted in decreasing and lower final occupancy in production forest than in set-asides, especially of specialist species. In set-aside stands, however, specialists increased over time to relatively high occupancies. 4. Synthesis. Colonization–extinction dynamics of wood-decaying fungi varied with species' degree of specialization. Increasing specialization was associated with increasing sensitivity of colonization rates to habitat conditions, and partly local connectivity, as well as with increasing extinction rates. Low landscape-scale occupancies of specialist as compared to generalist wood-decaying fungi are thus maintained by a combination of lower colonization rates, particularly in production forest, and higher extinction rates. colonization–extinction dynamics, decomposer fungi, dynamic occupancy model, ecological specialization, forestry, landscape ecology, land-use scenario, metapopulation

Climate change is pushing species ranges towards poles and mountain tops. Although many studies have documented local altitudinal shifts, knowledge of general patterns at a large spatial scale, such as a whole mountain range, is very limited. From a conservation perspective, studying altitudinal shifts is particularly important as mountain regions often represent biodiversity hotspots and are among the most vulnerable ecosystems. Here, we examine whether altitudinal shifts have occurred among birds in the Scandinavian mountains over 13 years and assess whether such shifts are related to species’ traits. Using abundance data, we show a clear pattern of uphill shifts in the mean altitudes of the bird species’ abundances across the Scandinavian mountains, with an average speed of 0.9 m per year. Out of 77 species, 54 shifted their ranges uphill. In general, the range shift was faster when the altitudinal range within the area was wider. Importantly, the altitudinal shift was strongly related to species’ longevity: short-lived species showed more pronounced altitudinal uphill shifts than long-lived species. Our results show that the altitudinal range shifts are not only driven by a small number of individuals at the range boundaries, but the overall bird abundances are on the move. This highlights the wide-ranging impact of climate change and the potential vulnerability of species with slow life-histories, as they appear unable to timely respond to rapidly changing climatic conditions.

The Arctic Ocean is undergoing rapid change: sea ice is being lost, waters are warming, coastlines are eroding, species are moving into new areas, and more. This paper explores the many ways that a changing Arctic Ocean affects societies in the Arctic and around the world. In the Arctic, Indigenous Peoples are again seeing their food security threatened and cultural continuity in danger of disruption. Resource development is increasing as is interest in tourism and possibilities for trans-Arctic maritime trade, creating new opportunities and also new stresses. Beyond the Arctic, changes in sea ice affect midlatitude weather, and Arctic economic opportunities may re-shape commodities and transportation markets. Rising interest in the Arctic is also raising geopolitical tensions about the region. What happens next depends in large part on the choices made within and beyond the Arctic concerning global climate change and industrial policies and Arctic ecosystems and cultures. Arctic Ocean Climate change Ecology Geopolitics Indigenous Peoples Sea ice

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2022 The Authors. Ecological Monographs published by Wiley Periodicals LLC on behalf of Ecological Society of America. Competition between apex predators can alter the strength of top-down forcing, yet we know little about the behavioral mechanisms that drive competition in multipredator ecosystems. Interactions between predators can be synergistic (facilitative) or antagonistic (inhibitive), both of which are widespread in nature, vary in strength between species and across space and time, and affect predation patterns and predator–prey dynamics. Recent research has suggested that gray wolf (Canis lupus) kill rates decrease where they are sympatric with brown bears (Ursus arctos), however, the mechanisms behind this pattern remain unknown. We used data from two long-term research projects in Scandinavia (Europe) and Yellowstone National Park (North America) to test the role of interference and exploitation competition from bears on wolf predatory behavior, where altered wolf handling and search time of prey in the presence of bears are indicative of interference and exploitation competition, respectively. Our results suggest the mechanisms driving competition between bears and wolves were dependent on the season and study system. During spring in Scandinavia, interference competition was the primary mechanism driving decreased kill rates for wolves sympatric with bears; handling time increased, but search time did not. In summer, however, when both bear and wolf predation focused on neonate moose, the behavioral mechanism switched to exploitation competition; search time increased, but handling time did not. Alternartively, interference competition did affect wolf predation dynamics in Yellowstone during summer, where wolves prey more evenly on neonate and adult ungulates. Here, bear presence at a carcass increased the amount of time wolves spent at carcasses of all sizes and wolf handling time for small prey, but decreased handling time for the largest prey. Wolves facilitate scavenging opportunities for bears, however, bears alter wolf predatory behavior via multiple pathways and are primarily antagonistic to wolves. Our study helps to clarify the behavioral mechanisms driving competition between apex predators, illustrating how interspecific interactions can manifest into population-level predation patterns.

Spatial capture–recapture (SCR) is now routinely used for estimating abundance and density of wildlife populations. A standard SCR model includes sub-models for the distribution of individual activity centers (ACs) and for individual detections conditional on the locations of these ACs. Both sub-models can be expressed as point processes taking place in continuous space, but there is a lack of accessible and efficient tools to fit such models in a Bayesian paradigm. Here, we describe a set of custom functions and distributions to achieve this. Our work allows for more efficient model fitting with spatial covariates on population density, offers the option to fit SCR models using the semi-complete data likelihood (SCDL) approach instead of data augmentation, and better reflects the spatially continuous detection process in SCR studies that use area searches. In addition, the SCDL approach is more efficient than data augmentation for simple SCR models while losing its advantages for more complicated models that account for spatial variation in either population density or detection. We present the model formulation, test it with simulations, quantify computational efficiency gains, and conclude with a real-life example using non-invasive genetic sampling data for an elusive large carnivore, the wolverine (Gulo gulo) in Norway. area search, binomial point process, continuous sampling, NIMBLE, non-invasive genetic sampling, Poisson point process, spatial capture–recapture, wolverine

Corrigendum: Ecological Indicators, Volume 137, April 2022, Article number 108627, https://doi.org/10.1016/j.ecolind.2022.108627. In order to understand species' sensitivity to habitat change, we must correctly determine if a species is associated with a habitat or not, and if it is associated, its degree of specialization for that habitat. However, definitions of species' habitat association and specialization are often static, categorical classifications that coarsely define species as either habitat specialists or generalists and can fail to account for potential temporal or spatial differences in association or specialization. In contrast, quantitative metrics can provide a more nuanced assessment, defining species' habitat associations and specialization along a continuous scale and accommodate for temporal or spatial variation, but these approaches are less widely used. Here we explore relative habitat use (RHU) as a metric for quantifying species' association with and degree of specialization for different habitat types. RHU determines the extent of a species' association with a given habitat by comparing its abundance in that habitat relative to its mean abundance across all other habitats. Using monitoring data for breeding birds across Europe from 1998 to 2017; we calculate RHU scores for 246 species for five habitat types and compared them to the literature-based classifications of their association with and specialization for each of these habitats. We also explored the temporal variation in species' RHU scores for each habitat and assessed how this varied according to association and degree of specialization. In general, species' RHU and literature-derived classifications were well aligned, as RHU scores for a given habitat increased in line with reported association and specialization. In addition, temporal variation in RHU scores were influenced by association and degree of specialization, with lower scores for those associated with, and those more specialized to, a given habitat. As a continuous metric, RHU allows a detailed assessment of species' association with and degree of specialization for different habitats that can be tailored to specific temporal and/or spatial requirements. It has the potential to be a valuable tool for identifying indicator species and in supporting the design, implementation and monitoring of conservation management actions.

Understanding how niche-based and neutral processes contribute to the spatial varia-tion in plant–pollinator interactions is central to designing effective pollination con-servation schemes. Such schemes are needed to reverse declines of wild bees and other pollinating insects, and to promote pollination services to wild and cultivated plants. We used data on wild bee interactions with plants belonging to the four tribes Loteae, Trifolieae, Anthemideae and either spring- or summer-flowering Cichorieae, sampled systematically along a 682 km latitudinal gradient to build models that allowed us to 1) predict occurrences of pairwise bee–flower interactions across 115 sampling locations, and 2) estimate the contribution of variables hypothesized to be related to niche-based assembly structuring processes (viz. annual mean temperature, landscape diversity, bee sociality, bee phenology and flower preferences of bees) and neutral processes (viz. regional commonness and dispersal distance to conspecifics). While neutral processes were important predictors of plant–pollinator distributions, niche-based processes were reflected in the contrasting distributions of solitary bee and bumble bees along the temperature gradient, and in the influence of bee flower preferences on the distri-bution of bee species across plant types. In particular, bee flower preferences separated bees into three main groups, albeit with some overlap: visitors to spring-flowering Cichorieae; visitors to Anthemideae and summer-flowering Cichorieae; and visitors to Trifolieae and Loteae. Our findings suggest that both neutral and niche-based pro-cesses are significant contributors to the spatial distribution of plant–pollinator inter-actions so that conservation actions in our region should be directed towards areas: Page 2 of 11near high concentrations of known occurrences of regionally rare bees; in mild climatic conditions; and that are surrounded by heterogenous landscapes. Given the observed niche-based differences, the proportion of functionally distinct plants in flower-mixes could be chosen to target bee species, or guilds, of conservation concern. Keywords: ecological networks, machine learning, plant–pollinator interactions, spatial, wild bees Neutral processes related to regional bee commonness and dispersal distances are important predictors of plant–pollinator networks along gradients of climate and landscape conditions

In ectotherms, adult body size commonly declines with increasing environmental temperature, a pattern known as the temperature-size rule. One influential hypothesis explaining this observation is that the challenge of obtaining sufficient oxygen to support metabolism becomes greater with increasing body size, and more so at high temperatures. Yet, previous models based on this hypothesis do not account for phenotypic plasticity in the physiology of organisms that counteracts oxygen limitation at high temperature. Here, we model the predicted strength of the temperature-size response using estimates of how both the oxygen supply and demand is affected by temperature when allowing for phenotypic plasticity in the aquatic ectotherm Daphnia magna. Our predictions remain highly inconsistent with empirical temperature-size responses, with the prior being close to one order of magnitude stronger than the latter. These results fail to provide quantitative support for the hypothesis that oxygen limitation drives temperature-size clines in aquatic ectotherms. Future studies into the role of oxygen limitation should address how the strength of the temperature-size response may be shaped by evolution under fluctuating temperature regimes. Finally, our results caution against applying deterministic models based on the oxygen limitation hypothesis when predicting future changes in ectotherm size distributions under climate change.

The fasting endurance hypothesis (FEH) predicts strong selection for large body size in mammals living in environments where food supply is interrupted over prolonged periods of time. The Arctic is a highly seasonal and food restricted environment, but contrary to predictions from the FEH, empirical evidence shows that Arctic mammals are often smaller than their temperate conspecifics. Intraspecific studies integrating physiology and behaviour of different‐sized individuals, may shed light on this paradox. We tested the FEH in free‐living Svalbard reindeer (Rangifer tarandus platyrhynchus). We measured daily energy expenditure (DEE), subcutaneous body temperature (Tsc) and activity levels during the late winter in 14 adult females with body masses ranging from 46.3 to 57.8 kg. Winter energy expenditure (WEE) and fasting endurance (FE) were modelled dynamically by combining these data with body composition measurements of culled individuals at the onset of winter (14 years, n = 140) and variation in activity level throughout winter (10 years, n = 70). Mean DEE was 6.3±0.7 MJ day−1. Lean mass, Tsc and activity had significantly positive effects on DEE. Across all 140 individuals, mean FE was 85±17 days (range 48–137 days). In contrast to the predictions of the FEH, the dominant factor affecting FE was initial fat mass, while body mass and FE were not correlated. Furthermore, lean mass and fat mass were not correlated. FE was on average 80% (45 days) longer in fat than lean individuals of the same size. Reducing activity levels by ~16% or Tsc by ~5% increased FE by 7%, and 4%, respectively. Our results fail to support the FEH. Rather, we demonstrate that (i) the size of fat reserves can be independent of lean mass and body size within a species, (ii) ecological and environmental variation influence FE via their effects on body composition, and (iii) physiological and behavioural adjustments can improve FE within individuals. Altogether, our results suggest that there is a selection in Svalbard reindeer to accumulate body fat, rather than to grow structurally large. he Arctic, activity, biologging, daily energy expenditure, doubly labelled water, intraspecific scaling, subcutaneous body temperature, Svalbard reindeer to accumulate body fat, rather than to grow structurally large.

1. Selection for crypsis has been recognized as an important ecological driver of animal colouration, whereas the relative importance of thermoregulation is more contentious with mixed empirical support. A potential thermal advantage of darker individuals has been observed in a wide range of animal species. Arctic animals that exhibit colour polymorphisms and undergo seasonal colour moults are interesting study subjects for testing the two alternative hypotheses: demographic performance of different colour morphs might be differentially affected by snow cover with a cryptic advantage for lighter morphs, or conversely by winter temperature with a thermal advantage for darker morphs. 2. In this study, we explored whether camouflage and thermoregulation might explain differences in reproduction and survival between the white and blue colour morphs of the Arctic fox Vulpes lagopus under natural conditions. 3. Juvenile and adult survival, breeding propensity and litter size were measured for 798 captive-bred and released or wild-born Arctic foxes monitored during an 11-year period (2007–2017) in two subpopulations in south-central Norway. We investigated the proportion of the two colour morphs and compared their demographic performance in relation to spatial variation in duration of snow cover, onset of snow season and winter temperatures. 4. After population re-establishment, a higher proportion of blue individuals was observed among wild-born Arctic foxes compared to the proportion of blue foxes released from the captive population. Our field study provides the first evidence for an effect of colour morph on the reproductive performance of Arctic foxes under natural conditions, with a higher breeding propensity of the blue morph compared to the white one. Performance of the two colour morphs was not differentially affected by the climatic variables, except for juvenile survival. Blue morph juveniles showed a tendency for higher survival under colder winter temperatures but lower survival under warmer temperatures compared to white morph juveniles. 5. Overall, our findings do not consistently support predictions of the camouflage or the thermoregulation hypotheses. The higher success of blue foxes suggests an advantage of the dark morph not directly related to disruptive selection by crypsis or thermoregulation. Our results rather point to physiological adaptations and behavioural traits not necessarily connected to thermoregulation, such as stress response, immune function, sexual behaviour and aggressiveness. Our findings highlight the need to explore the potential role of genetic linkage or pleiotropy in influencing the fitness of white and blue Arctic foxes as well as other species with colour polymorphisms. apparent survival, Arctic fox, camouflage, capture–mark– recapture models, colour polymorphism, fitness, reproductive performance, snow cover This is an open access article under the terms of the Creative Commons Attribution-NonCommercial- NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2021 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society

Natural and cultural diversity is gaining wider global recognition as the key to sustainable development. This article looks at the challenges of conserving marine biocultural diversity by investigating the unique heritage of marine salmon fisheries through a case study of a small group of marine fisheries in Norway, still fishing for Atlantic salmon Salmo salar L. Tight relationships between declining natural resources and daily struggles to keep cultural heritage alive are highlighted through theoretical perspectives of social identity and local ecological knowledge. The theoretical lens of social identity contributes to better understanding tensions between scientific and local knowledge by bringing forward social categorisation, polarisation and power relations as drivers of conflicts. Involvement of local communities and respect for their cultural heritage, knowledge and practices can assist in more effective management and governance of multifunctional biocultural landscapes, and contribute to their resilience and adaptability. coastal heritage, cultural and biological diversity, local ecological knowledge, salmon, small-scale fisheries, social identity, traditions

Movement ecology is increasingly relying on experimental approaches and hypothesis testing to reveal how, when, where, why, and which animals move. Movement of megafauna is inherently interesting but many of the fundamental questions of movement ecology can be efficiently tested in study systems with high degrees of control. Lakes can be seen as microcosms for studying ecological processes and the use of high-resolution positioning systems to triangulate exact coordinates of fish, along with sensors that relay information about depth, temperature, acceleration, predation, and more, can be used to answer some of movement ecology's most pressing questions. We describe how key questions in animal movement have been approached and how experiments can be designed to gather information about movement processes to answer questions about the physiological, genetic, and environmental drivers of movement using lakes. We submit that whole lake telemetry studies have a key role to play not only in movement ecology but more broadly in biology as key scientific arenas for knowledge advancement. New hardware for tracking aquatic animals and statistical tools for understanding the processes underlying detection data will continue to advance the potential for revealing the paradigms that govern movement and biological phenomena not just within lakes but in other realms spanning lands and oceans. Correction published here, October 2021: https://doi.org/10.1186/s40462-021-00285-3

Accurate occurrence data is necessary for the conservation of keystone or endangered species, but acquiring it is usually slow, laborious, and costly. Automated acoustic monitoring offers a scalable alternative to manual surveys, but identifying species vocalisations requires large manually annotated training datasets, and is not always possible (e.g., for silent species). A new, intermediate approach is needed that rapidly predicts species occurrence without requiring extensive labelled data.We investigated whether local soundscapes could be used to infer the presence of 32 avifaunal and seven herpetofaunal species across a tropical forest degradation gradient in Sabah, Malaysia. We developed a machine-learning based approach to characterise species indicative soundscapes, training our models on a coarsely labelled manual point-count dataset.Soundscapes successfully predicted the occurrence of 34 out of the 39 species across the two taxonomic groups, with area under the curve (AUC) metrics of up to 0.87 (Bold-striped Tit-babbler Macronus bornensis). The highest accuracies were achieved for common species with strong temporal occurrence patterns.Soundscapes were a better predictor of species occurrence than above-ground biomass – a metric often used to quantify habitat quality across forest degradation gradients.Synthesis and applications: Our results demonstrate that soundscapes can be used to efficiently predict the occurrence of a wide variety of species. This provides a new direction for audio data to deliver large-scale, accurate assessments of habitat suitability using cheap and easily obtained field datasets.

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

Background: Human food subsidies can provide predictable food sources in large quantities for wildlife species worldwide. In the boreal forest of Fennoscandia, gut piles from moose (Alces alces) harvest provide a potentially important food source for a range of opportunistically scavenging predators. Increased populations of predators can negatively affect threatened or important game species. As a response to this, restrictions on field dressing of moose are under consideration in parts of Norway. However, there is a lack of research to how this resource is utilized. In this study, we used camera-trap data from 50 gut piles during 1043 monitoring days. We estimated depletion of gut piles separately for parts with high and low energy content, and used these results to scale up gut pile density in the study area. We identified scavenger species and analyzed the influences of gut pile quality and density on scavenging behavior of mammals and corvids (family Corvidae). Results: Main scavengers were corvids and red fox (Vulpes vulpes). Parts with high energy content were rapidly consumed, mainly by corvids that were present at all gut piles shortly after the remains were left at the kill site. Corvid presence declined with days since harvest, reflecting reduction in gut pile quality over time independent of gut pile density. Mammals arrived 7–8 days later at the gut piles than corvids, and their presence depended only on gut pile density with a peak at intermediate densities. The decline at high gut pile densities suggest a saturation effect, which could explain accumulation of gut pile parts with low energy content. Conclusions: This study shows that remains from moose harvest can potentially be an important food resource for scavengers, as it was utilized to a high degree by many species. This study gives novel insight into how energy content and density of resources affect scavenging patterns among functional groups of scavengers. Keywords: Carrion ecology, Scavenging, Human subsidies, Pulsed resources, Gut piles, Scavenger community

According to classic theory, species interactions are less important than climatic variation for species’ population dynamics and distributions in climatically harsh regions compared with more climatically benign regions. In boreal ecosystems, the cyclic dynamics of rodents strongly affect many other species, including ground-nesting birds. According to the ‘alternative prey hypothesis’ (APH), high rodent densities positively affect the abundance of ground-nesting birds due to predator-mediated interactions. We analysed a spatiotemporal dataset of willow ptarmigan ( Lagopus lagopus ) and rodents to examine how the role of predator-mediated interactions changes along a climatic harshness gradient in comparison with climatic variation. Ptarmigan and rodent data were collected during a national program of line-transect sampling across Norway during 2007–2017. We build a hierarchical Bayesian model to estimate the sensitivity of ptarmigan populations to interannual variation in climate and rodent occurrence. Ptarmigan abundance was positively linked with rodent occurrence, consistent with the APH. Moreover, we found that both rodent dynamics and temporal climatic variation had stronger effects on ptarmigan in colder regions. Our study highlights how species interactions play an important role for the population dynamics of species at higher latitudes and suggest that they become even more important in the most climatically harsh regions.

1. Due to globalisation, trade and transport, the spread of alien species is increasing dramatically. Some alien species become ecologically harmful by threatening native biota. This can lead to irreversible changes in local biodiversity and ecosystem functioning, and, ultimately, to biotic homogenisation. 2. We risk-assessed all alien plants, animals, fungi and algae, within certain delimitations, that are known to reproduce in Norway. Mainland Norway and the Arctic archipelago of Svalbard plus Jan Mayen were treated as separate assessment areas. Assessments followed the Generic Ecological Impact Assessment of Alien Species (GEIAA) protocol, which uses a fully quantitative set of criteria. 3. A total of 1519 species were risk-assessed, of which 1183 were species reproducing in mainland Norway. Among these, 9% were assessed to have a severe impact, 7% high impact, 7% potentially high impact, and 49% low impact, whereas 29% had no known impact. In Svalbard, 16 alien species were reproducing, one of which with a severe impact. 4. The impact assessments also covered 319 so-called door-knockers, i.e. species that are likely to establish in Norway within 50 years, and 12 regionally alien species. Of the door-knockers, 8% and 10% were assessed to have a severe and high impact, respectively. 5. The impact category of most species was driven by negative interactions with native species, transformation of threatened ecosystems, or genetic contamination. The proportion of alien species with high or severe impact varied significantly across the different pathways of introduction, taxonomic groups, time of introduction, and the environments colonised, but not across continents of origin. 6. Given the large number of alien species reproducing in Norway and the preponderance of species with low impact, it is neither realistic nor necessary to eradicate all of them. Our results can guide management authorities in two ways. First, the use of quantitative assessment criteria facilitates the prioritisation of management resources across species. Second, the background information collected for each species, such as introduction pathways, area of occupancy and ecosystems affected, helps designing appropriate management measures. 1. Globalisering, handel og transport fører til en dramatisk økning i spredningen av fremmede arter. Noen fremmede arter er skadelige og truer det stedegne naturmangfoldet. Lokalt kan dette medføre irreversible endringer i det lokale biologiske mangfoldet og økosystemenes funksjon; globalt en homogenisering av artssammensetningen. 2. Vi har gjennomført risikovurderinger av alle fremmede planter, dyr, sopper og alger som reproduserer i Norge og oppfyller visse avgrensninger. Svalbard og Jan Mayen ble behandla som et eget vurderingsområde, adskilt fra Fastlands‐Norge. Risikovurderingene ble gjort i tråd med GEIAA (Generic Ecological Impact Assessment of Alien Species), som benytter et rent kvantitativt kriteriesett. 3. Totalt ble 1519 arter risikovurdert, hvorav 1183 reproduserte i Fastlands‐Norge. Av disse ble 9 % vurdert til å utgjøre en svært høy risiko, 7 % en høy risiko, 7 % en potensielt høy risiko, 49 % en lav risiko og 29 % ingen kjent risiko. På Svalbard forekom 16 reproduserende fremmede arter, hvorav én med svært høy risiko. 4. Risikovurderingene omfatta også 319 såkalte dørstokkarter, dvs. fremmede arter som antas å kunne etablere seg i Norge innen 50 år, samt 12 regionalt fremmede arter. Blant dørstokkartene ble 8 % og 10 % vurdert til å utgjøre en svært høy respektive høy risiko. 5. For de fleste arter ble risikokategorien bestemt av artenes interaksjoner med stedegne arter, tilstandsendringer i trua naturtyper eller genetisk forurensning. Andelen av fremmede arter med høy eller svært høy risiko varierte signifikant på tvers av ulike introduksjonsveier, artsgrupper, tidspunkt for introduksjon og koloniserte naturtyper, men ikke på tvers av opphavsområder. 6. Gitt det store antallet av fremmede arter som reproduserer i Norge, og overvekten av arter som har lav risiko, er det verken realistisk eller nødvendig å utrydde alle. Resultatene våre kan hjelpe forvaltningsmyndighetene på to måter. For det første gjør bruken av kvantitative kriterier det lettere å prioritere ressurser på tvers av arter. For det andre kan passende forvaltningstiltak utarbeides på grunnlag av den innsamla bakgrunnsinformasjonen om artene, f.eks. deres spredningsveier, forekomstareal og berørte naturtyper. This is an open access article under the terms of the Creative Commons Attribution License, which permits use,distribution and reproduction in any medium, provided the original work is properly cited.c 2020 The Authors. Ecological Solutions and Evidence published by John Wiley & Sons Ltd on behalf of British Ecological Society

Assessing the vulnerability of species to climate change serves as the basis for climate-adaptation planning and climate-smart conservation, and typically involves an evaluation of exposure, sensitivity, and adaptive capacity (AC). AC is a species’ ability to cope with or adjust to changing climatic conditions, and is the least understood and most inconsistently applied of these three factors. We propose an attribute-based framework for evaluating the AC of species, identifying two general classes of adaptive responses: “persist in place” and “shift in space”. Persist-in-place attributes enable species to survive in situ, whereas the shift-in-space response emphasizes attributes that facilitate tracking of suitable bioclimatic conditions. We provide guidance for assessing AC attributes and demonstrate the framework's application for species with disparate life histories. Results illustrate the broad utility of this generalized framework for informing adaptation planning and guiding species conservation in a rapidly changing climate. publishedVersion

The determinants of intraspecific stoichiometric variation remain difficult to elucidate due to their multiple ori- gins (e.g. genetic vs. environmental) and potential interactive effects. We evaluated whether two size-selected lines of medaka (Oryzias latipes) with contrasted life-history strategies (small- and large-breeder lines with slow growth and early maturity vs. fast growth and late maturity) differed in their organismal stoichiometry (percentage and ratios of carbon [C], nitrogen [N] and phosphorus [P]) in a mesocosm experiment. We also tested how size-selection interacted with environmental conditions (i.e. two levels of fish density and light intensity), body condition and sex. Results showed that large-breeder fish were significantly N-enriched compared to small-breeders, while the two size-selected lines did not differ in body P composition. Size-selection interacted with density – high density only affected small-breeders leading to decreasing %C and C: N – and with sex – large-breeder females had higher %C and C:N values than large-breeder males. Finally, C:P and N:P ratios in- creased with body condition due to decreasing %P. Overall, our results show that the ecological consequences of size-selective mortality extend to organismal stoichiometry and may, from there, change nutrient cycling and ecosystem functioning. publishedVersion

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. The 8.2 ka bp cooling event is assumed to be the most clearly marked abrupt climate event in the Holocene at northern mid‐ to high latitudes. In this study, we simulate the vegetation responses to the 8.2 ka bp climate change event over Europe and Northern Africa. Our results show that all dominant plant functional types (PFTs) over Europe and North Africa respond to these climate changes, but the magnitude, timing and impact factor of their responses are different. Compared with pollen‐based vegetation reconstructions, our simulation generally captures the main features of vegetation responses to the 8.2 ka bp event. Interestingly, in Western Europe, the simulated vegetation after perturbation is different from its initial state, which is consistent with two high‐resolution pollen records. This different vegetation composition indicates the long‐lasting impact of abrupt climate change on vegetation through eco‐physiological and ecosystem demographic processes, such as plant competition. Moreover, our simulations suggest a latitudinal gradient in the magnitude of the event, with more pronounced vegetation responses to the severe cooling in the north and weaker responses to less severe cooling in the south.

Understanding habitat preferences and distribution of threatened species is a cornerstone of conservation, however many of the techniques available can be resource intensive. One cost-effective method is by collecting information on species presence and absence from people who regularly interact with the area of interest, also known as Local Ecological Knowledge (LEK). However, the reliability of this type of data has been questioned, especially when there is a possibility that the focal species is being misidentified or their presence misreported. This can introduce false negatives, when a species is present but has not been reported, and false positives, when the species has been reported but is not present. These biases are not always accounted for which can result in the under- or overestimation of species presence. To better understand the reliability of LEK data, we compared the outputs of five different analytical techniques to that of a more widely accepted approach, resource selection functions (RSF), using GPS-collar data from three different carnivore species (African lion Panthera leo, cheetah Acinonyx jubatus and African wild dog Lycaon pictus). Hierarchical models which accounted for the possibilities of both false negatives and false positives most closely matched that of the RSFs, especially for the two rarer species; African wild dog and cheetah. Our results show that when both false negatives and false positives are accounted for that LEK can be used as a rapid and cost-efficient tool for assessing threatened species which can be adopted into practical conservation projects. Carnivores Detection probability False positives GPS telemetry data Interview survey Occupancy models Species distribution © 2020. This is the authors’ accepted and refereed manuscript to the article. Locked until 24.07.2021 due to copyright restrictions. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

Effective evidence-based nature conservation and habitat management relies on developing and refining our methodological toolbox for detecting critical ecological changes at an early stage. This requires not only optimizing the use and integration of evidence from available data, but also optimizing methods for dealing with imperfect knowledge and data deficiencies. For policy and management relevance, ecological data are often synthesized into indicators, which are assessed against reference levels and limit values. Here we explore challenges and opportunities in defining ecological condition in relation to a reference condition reflecting intact ecosystems, as well as setting limit values for good ecological condition, linked to critical ecological thresholds in dose–response relationships between pressures and condition variables. These two concepts have been widely studied and implemented in aquatic sciences, but rarely in terrestrial systems. In this paper, we address practical considerations, theoretical challenges and possible solutions using different approaches to determine reference and limit values for good ecological condition in terrestrial ecosystems, based on empirical experiences from a case study in central Norway. We present five approaches for setting indicator reference values for intact ecosystems: absolute biophysical boundaries, reference areas, reference communities, ecosystem dynamics based models, and habitat availability based models. We further present four approaches for identifying indicator limit values for good ecological condition: empirically estimated values, statistical distributions, assumed linear relationships, and expert judgement-based limits. This exercise highlights the versatile and robust nature of ecological condition assessments based on reference and limit values for different management purposes, for situations where knowledge of the underlying relationships is lacking, and for situations limited by data availability. Ecological condition Index Management Reference condition Terrestrial This is an open access article distributed under the terms of the Creative Commons CC-BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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

En rekke taigaarter har i mange områder vist seg å ha en negativ bestandsutvikling. Tilbakegangen knyttes ofte til skogbruk med flatehogst og tette plantefelt, som fører til fragmentering, ødeleggelser og tap av leveområder. Lavskrike (Perisoreus infaustus) kan være sårbar for slike inngrep, men i Norge har vi liten kunnskap om hvordan habitatvalg og bestandsutvikling er påvirket av skogbruk. For å få en bedre oversikt over hvilke habitater lavskrike foretrekker, og hvilke miljøfaktorer som påvirker den, gjennomførte vi ca. 360 km linjetaksering i egnede biotoper på 37 lokaliteter innenfor artens kjente utbredelsesområde i Sør-Norge. Vi registrerte 159 lavskriker, og fant at den har en klar preferanse for gammelskog. Den unngår åpnere områder og foretrekker noe tettere skog. Mindre områder med hogst innenfor reviret ble brukt aktivt til næringssøk. Vi fant ikke tegn til at lavskrike unngår hytter og hyttefelt. Heller ikke lot det til at den var fraværende der vi observerte andre kråkefugler. Vi gjennomførte også en spørreundersøkelse for å få et bedre bilde av endringer for lavskrike over tid. Spørreundersøkelsen viste ikke en overvekt av nedgang for lavskrike, men det var en signifikant sammenheng mellom hogst og negativ bestandsutvikling. Spørreundersøkelsen viste også signifikant økning for nøtteskrike, skjære og kråke i undersøkelsesområdet. Lavskrike ser ut til å ha blitt borte eller mer fåtallig i randområdene mot sørligere deler av utbredelsesområdet. Vi konkluderer med en økende negativ bestandsutvikling jo lengre man kommer fra artens kjerneområder. I kjerneområdene later bestanden til å være relativt stabil. Fortsatt bestandsskogbruk kan tvinge lavskrike til å bruke mindre egnede reirlokaliteter, noe som i kombinasjon med økt forekomst av kråkefugler som følge av økt menneskelig tilstedeværelse, kan føre til en høyere grad av reirpredasjon og redusert hekkesuksess. Et mildere klima kan forsterke disse tendensene, og samtidig føre til at områder med tørre og kalde nok vintre til at hamstret næring konserveres, blir mindre. Lavskrike vil være avhengig av større sammenhengende områder med solide innslag av gammelskog for å opprettholde en levedyktig bestand. Mer vern av høyereliggende barskog, og bevaring av mindre og tettere hekkebiotoper innenfor revirene, vil kunne være et effektivt tiltak for å bedre forholdene for lavskrike. M-NF

Ocean acidification and carbonation, driven by anthropogenic emissions of carbon dioxide (CO2), have been shown to affect a variety of marine organisms and are likely to change ecosystem functioning. High latitudes, especially the Arctic, will be the first to encounter profound changes in carbonate chemistry speciation at a large scale, namely the under-saturation of surface waters with respect to aragonite, a calcium carbonate polymorph produced by several organisms in this region. During a CO2 perturbation study in Kongsfjorden on the west coast of Spitsbergen (Norway), in the framework of the EU-funded project EPOCA, the temporal dynamics of a plankton bloom was followed in nine mesocosms, manipulated for CO2 levels ranging initially from about 185 to 1420 μatm. Dissolved inorganic nutrients were added halfway through the experiment. Autotrophic biomass, as identified by chlorophyll a standing stocks (Chl a), peaked three times in all mesocosms. However, while absolute Chl a concentrations were similar in all mesocosms during the first phase of the experiment, higher autotrophic biomass was measured as high in comparison to low CO2 during the second phase, right after dissolved inorganic nutrient addition. This trend then reversed in the third phase. There were several statistically significant CO2 effects on a variety of parameters measured in certain phases, such as nutrient utilization, standing stocks of particulate organic matter, and phytoplankton species composition. Interestingly, CO2 effects developed slowly but steadily, becoming more and more statistically significant with time. The observed CO2-related shifts in nutrient flow into different phytoplankton groups (mainly dinoflagellates, prasinophytes and haptophytes) could have consequences for future organic matter flow to higher trophic levels and export production, with consequences for ecosystem productivity and atmospheric CO2.

Rapporten viser status for ECONADA-prosjektet ved årsskiftet 2011/2012.

After extensive exploratory investigations into crenic habitats at the beginning of the 1990s, a number of springs were selected and long-term ecological research programmes independently initiated in the Berchtesgaden National Park (north-eastern Alps, Bavaria) and the Adamello-Brenta Nature Park (south-eastern Alps, Trentino). Following more than a decade of standardized work, this paper presents a selection of results from both sides of the Alps, with a focus on zoobenthos in Bavaria and on pro- and eukaryotic algae in Trentino. In order to test the assumption that permanent springs are particularly suitable habitats for long-term ecological research, the following topics are addressed: (1) taxonomic diversity and relationships between diversity and spring typology; (2) transverse gradients in crenic habitats, hygrophilous terrestrial invertebrates and xerotolerant algae; (3) possibilities of documenting changes in species composition over decadal time scales ("medium-term") based on emergence traps, benthos, and benthic algae. The data obtained show that: (1) crenic habitats support particularly high biological diversity (but a thorough documentation of insect diversity is impossible without emergence studies); (2) helocrenes are the most species-rich habitats, for both invertebrates and diatoms; (3) dynamic (unstable) and occasionally-impacted springs show identifiable signs of medium-term change, whilst particularly complex and stable crenic habitats seem to be controlled by internal processes. Our results suggest that: (1) the meiofauna is likely to react directly to environmental change, while emergers and the hygrophilous terrestrial fauna are indirectly affected, and (2) diatoms react both to direct effects of environmental change, e.g. discharge and hydrochemistry, and to indirect effects on the surroundings of the spring. Based on our results, long-term research strategies are discussed. For long-term studies, we propose a focus on meiofauna and diatoms, with target-oriented emergence studies and macroscopic benthic algal analyses. This could form the basis for an integrated and uniform approach to studies of these habitats worldwide. This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Begrepet naturskog blir ofte brukt i skogbruk-, friluftsliv- og naturvern-sammenheng. Gjennom et opprop har mange forskere og fagpersoner oppfordret skogbruket til å avstå fra hogst i naturskogområder (Arbeidsgruppen for miljøorganisasjoner i Norge, 1998), og begrepet inngår i Levende skogs standard for biologisk viktige områder (Levende skog 1998). Skogmeldingen (Stortingsmelding nr 17, 1998-99) signaliserer at det kan være aktuelt å sette i verk en nærmere kartlegging av naturskogarealer, men etterlyser en definisjon som kan gi begrepet et konsistent og praktisk rettet innhold. På denne bakgrunnen har Landbruksdepartementet gitt Skogforsk og NINA i oppdrag å (1) gi en oversikt over hvordan begrepet naturskog brukes i ulike sammenhenger, (2) sammenfatte eksisterende kunnskap om økologi, arter og miljøverdier i slik skog, og (3) vurdere hensiktsmessigheten av – og eventuelt gi anbefalinger om – en norsk definisjon av naturskog, så langt som mulig forankret i internasjonal forståelse og relevant skog- og miljøstatistikk. I tillegg ønsket departementet vurderinger når det gjelder mer presise kriterier og indikatorer for naturskog, som eventuelt kan gi grunnlag for registrering, kartlegging og overvåking. En gjennomgang av begrepet naturskog avdekker en rekke ulike tilnærminger og definisjoner. Oppsummert framstår naturskog som et kvalitativt uttrykk for skog som relativt sett er lite påvirket av mennesker, dvs skog der naturlige økologiske prosesser er dominerende. Naturskog blir ofte brukt som motsats til kulturskog, der de økologiske prosessene i stor grad er modifisert av menneskelig aktivitet, i første rekke skogbruk. En sammenfatning av eksisterende kunnskap om økologi, arter og miljøverdier viser at urørt eller lite påvirket skog omfatter et bredt spekter av skogtilstander avhengig av skogtype og naturgitte suksesjoner og forstyrrelser. En gjennomgang av den historiske utnyttelsen av skogarealene viser at en stor del av skogarealet er sterkt påvirket av mennesker. Likevel har skogen i Norge i dag en betydelig grad av naturlige strukturer og sammensetninger. Skogstatistikken viser at det er gradvise strukturelle overganger fra kulturskog til naturskog, og det er således ikke funnet faglig grunnlag for å sette en konsistent grense som entydig skiller disse to fra hverande. Arealomfanget av naturskog vil følgelig avhenge av hvor strenge krav til naturlighet, eller urørthet, som legges til grunn. Det foreligger allerede flere definisjoner på hva naturskog er, basert på ulike sett av kriterier og intensjoner. Basert på gjennomgangen og diskusjonen i denne utredningen foreslås følgende generelle definisjon lagt til grunn for begrepet naturskog i Norge: Naturskog er skog framkommet ved naturlig foryngelse av stedegent genmateriale. Menneskelig påvirkning har funnet sted i så liten utstrekning, for så lang tid tilbake, eller er utført på en slik måte, at skogens naturlige struktur, sammensetning, og økologiske prosesser ikke er endret i vesentlig grad. Denne definisjonen ligger nært opptil de definisjonene som allerede er brukt i nordisk sammenheng, i arbeidet med barskogverneplanen, og som er skissert i Skogmeldingen. Den foreslåtte definisjonen er generell i formen, og det er ikke funnet faglig konsistente terskelverdier for hva som er vesentlige avvik fra en naturlig struktur, sammensetning og dynamikk. En eventuell registrering av naturskog krever følgelig at man ut fra normative (politiske) verdivurderinger fastlegger hvilke krav til urørthet, eller andre egenskaper ved skogen, som skal legges til grunn for kartleggingen (f.eks. 5% minst påvirkete områder, eller en viss andel av lite påvirket gammelskog). […] Naturskog i Norge. Definisjoner, økologi og bruk i norsk skog- og miljøforvaltning