Climate change and biodiversity loss are among the most pressing issues of our time. Lichens have been shown to be sensitive to climate change, but responses are species-specific and contradictory trends have been reported. This review addresses lichen biology in relation to climate change and we overview the responses of lichens (e.g. biotic interactions, species distribution shifts and lichen acclimatisation, adaptation and extinction) to climate (e.g. temperature, precipitation, CO2-levels, snow). Research shows mainly adverse or alarming effects of climate change on lichens, but there is not yet a generalisable understanding of the topic. We argue that contradictory trends emerge partly because relatively few studies have been conducted and they encompass a variety of locations, taxa, and methods, which makes them difficult to compare. Moreover, many aspects of lichens are still insufficiently understood, including species diversity, distributions, functional traits and biotic interactions with other organisms. We highlight that future studies would benefit from: 1) Developing a set of model species and also embarking full community studies; 2) Better species data, including monitoring programmes and trait data; 3) Improved conservation planning and Red List evaluations and 4) Acknowledging that lichens are small ecosystems and climate change may affect the partners in ways we do not understand yet.

Microclimatic heterogeneity in high-latitude landscapes plays a key role in shaping ecosystem functioning, biodiversity and resilience to environmental change. Microclimates are shaped by topography, vegetation and synoptic atmospheric conditions. However, the translation of macroscale synoptic conditions into fine-scale temperature variability has rarely been investigated empirically. We examined summer near-surface air temperatures in relation to synoptic conditions (classified from calm and clear to windy and cloudy) and analysed changes in microclimatic drivers and spatial heterogeneity. The study was conducted in a high-latitude landscape, utilizing macroclimate data from weather stations and microclimate data from a dense network of 193 stations distributed across a heterogeneous landscape characterized by strong environmental gradients. Our results revealed that fine-scale temperature heterogeneity is strongly connected to synoptic conditions. The temperature range across the landscape was highest (10 °C Tmin and 16 °C Tmax) on calm, clear days, whereas on windy and cloudy days differences were significantly smaller (5 °C Tmin and 7 °C Tmax). Macroscale variations influenced microscale temperature heterogeneity differently depending on landscape properties: topography primarily affected minimum temperatures, while both topography and vegetation properties contributed to variations in maximum temperatures. Our findings highlight the variation in microclimate temperature heterogeneity across a high-latitude landscape, largely driven by synoptic conditions that regulate air mixing and radiation fluxes. By demonstrating how large-scale atmospheric patterns influence fine-scale thermal variability, our results offer deeper insight into key microclimatic drivers under different weather conditions. This understanding is crucial for predicting how microclimates will respond to climate change in high-latitude ecosystems.

Shrubification (i.e., increasing shrub abundance) and thermophilisation (i.e., increasing dominance of warmth-demanding species) are among the most widely documented imprints of climate change on mountain ecosystems. Still, it remains insufficiently quantified how increasing shrub cover alters the near-ground microclimate and snow duration, and in turn, how this interacts with the climate-change responses of alpine plant communities. To this end, we leveraged 21 years of vegetation resampling data and soil temperature time-series from 576 permanent plots positioned on European mountaintops and covering the treeline ecotone up to the middle alpine belt. Snow duration decreased faster in plots with stronger macroclimate warming, which in turn led to a rise in minimum soil temperatures of 0.28°C per decade across all plots. Overall thermophilisation rates were higher in sheltered habitats with snow accumulation, while habitats with higher shrub cover showed faster loss of cold-adapted species. Further research is needed to disentangle the joint effects of shrubs, snow and microclimates, yielding more accurate projections of climate-induced plant community reshuffling in alpine habitats.

Leaf functional traits are informative of plant fitness and functions in ecosystems. These functional traits and their variation across geographic extents are much studied but less is known about their temporal variation over a growing season. Here, we provide an analysis of the seasonal variation in six leaf functional traits of 11 sub-Arctic vascular plant species in northern Finland, highlighting significant temporal dynamics over a growing season. Our findings reveal that functional traits, including specific leaf area, leaf dry matter content, leaf area, leaf dry mass, brightness index, and greenness index, exhibit considerable variation across the 15-week growing season. These temporal variations are influenced by plant growth forms, with distinct patterns observed among forbs, deciduous shrubs and evergreen shrubs. Our analyses show that the ranking of species based on traits is rather well preserved during the peak growing season in the most commonly used traits. Consequently, the timing of sampling has a rather minor impact on the relative trait differences across species as long as the sampling is not conducted in the very beginning and end of the growing season. However, if different species are measured at different times of the year, the seasonal effect can be notable. The growth forms often follow roughly similar temporal dynamics, and therefore, the error can be especially strong when comparing species across different growth forms.

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

Abstract Understanding global biodiversity patterns and their drivers is a prerequisite for countering the biodiversity crisis. In this paper, we introduce a novel generalized linear model, Hubbell regression, to estimate a key biodiversity descriptor, the fundamental biodiversity number. This can be converted into a set of biodiversity descriptors, including Shannon and Simpson indices, and more. Hence, quantifying the impact of environmental conditions on the fundamental biodiversity number allows us to predict the general properties of local biodiversity in any setting. In addition to having a strong mathematical foundation, Hubbell regression consistently outperformed current state-of-the-art models in predicting global biodiversity. We apply the method to arthropods, which account for the majority of terrestrial biodiversity. By parameterizing the models using samples of 1.78 million arthropods from 2415 samples collected at 135 sites spanning all continents, we pinpoint the drivers of arthropod biodiversity and its features at the global scale. We find that actual evapotranspiration is the single largest predictor of arthropod diversity and explains nearly 30% of the variation in richness. Moreover, we infer that high human activity has led to a 21.3 % and 29.2% decrease in potential insect richness in tropical and dry zones, respectively, but increased insect richness in polar regions. These insights bring a new foundation for biodiversity research and action.

Biodiversity is declining in the boreal forest biome. To halt this loss, deeper understanding of the mechanisms driving the occurrence and abundance patterns of boreal forest species is needed. It is increasingly acknowledged that forest features, such as canopy cover, influence abiotic and biotic conditions within forests. However, the importance of these mechanisms for boreal forest species remains poorly understood. Here, we assess three hypothesized mechanisms by which forest features influence the occurrence and abundance of Calypso bulbosa, a declining boreal orchid. Using Structural Equation Models and a unique dataset collected across 75 presence and 53 absence plots in northern Finland, we test whether canopy cover influences the species by altering microclimatic conditions (hypothesis 1), light and vegetation composition (H2), or whether deadwood, old trees and tree species diversity impact C. bulbosa (H3) by, for example, altering the availability of symbiotic partners. Our results provide support for all three hypothesized mechanisms. Occurrence peaked at intermediate soil moisture, whereas soil moisture was shaped by tree species diversity: higher diversity increased soil moisture, likely due to a buffering effect of denser, mixed canopies (H1). A higher cover of animal-pollinated plants increased occurrence, likely by facilitating the pollination of C. bulbosa. The cover of animal-pollinated plants, in turn, peaked at intermediate canopy cover and increased with deadwood, potentially reflecting the effects of light availability (H2). Occurrence was also directly affected by canopy cover, with intermediate cover providing the most suitable (likely light-driven) conditions (H2), while the abundance of the species increased with the number of old trees, potentially due to greater availability of symbiotic partners (H3). These findings offer valuable insights for ecological research and conservation practice. They also emphasize the need for a deeper understanding of how forest management, together with climate change, will affect declining boreal forest species.

The Arctic climate is rapidly warming, but long-term changes in extreme weather events that cause major ecosystem disturbances are not well understood. Here, by using a state-of-the-art atmospheric reanalysis spanning the past seven decades, we show that, in many parts of the terrestrial Arctic, the frequency of extreme weather events has increased sharply. We found pronounced spatial variability in bioclimatic extremes during the past 30 years, including more droughts in the high-Arctic and greater area affected by winter-warming and rain-on-snow events, especially in the European Arctic region. Across one-third of the Arctic domain, such extreme events have only recently begun to occur. Thus, the Arctic is entering a novel era of bioclimatic extremes with likely severe consequences on cold ecosystems.

Abstract We present here FennoTraits, which is a dataset of plant functional trait and community composition data which we collected from Fennoscandia across northern Finland, Norway, and Sweden in 2016-2025. This dataset has 42 049 abundance estimations and 155 794 functional trait observations from 10 traits representing 373 vascular plant species collected from 1 235 study sites within seven study areas. The trait measurements consist of size-structural, leaf economic, leaf spectral, and reproductive traits. The species represent the majority of the native vascular plant species that occur at the seven study areas, and many of the species occur in all seven areas across the two biomes and their ecotone: tundra and boreal forests. Each study area has distinct characteristics and a range of habitats: tundra, meadows, wetlands, shrublands, and boreal forests. These areas are under low anthropogenic influence, and many of the sites are within protected areas that are reserved for nature conservation and scientific research. Finally, we provide with this dataset a general description of the main trait patterns and profiles of the northern European flora.

Abstract Most biodiversity dynamics and ecosystem processes on land take place in microclimates that are decoupled from the climate as measured by standardised weather stations in open, unshaded locations. As a result, microclimate monitoring is increasingly being integrated in many studies in ecology and evolution. Overviews of the protocols and measurement methods related to microclimate are needed, especially for those starting in the field and to achieve more generality and standardisation in microclimate studies. Here, we present 10 practical guidelines for ground‐based research of terrestrial microclimates, covering methods and best practices from initial conceptualisation of the study to data analyses. Our guidelines encompass the significance of microclimates; the specifics of what, where, when and how to measure them; the design of microclimate studies; and the optimal approaches for analysing and sharing data for future use and collaborations. The paper is structured as a chronological guide, leading the reader through each step necessary to conduct a comprehensive microclimate study. At the end, we also discuss further research avenues and development in this field. With these 10 guidelines for microclimate monitoring, we hope to stimulate and advance microclimate research in ecology and evolution, especially under the pressing need to account for buffering or amplifying abilities of contrasting microhabitats in the context of global climate change.

The Afromontane region harbors ancient grasslands with high levels of endemism, now under threat from land-use change, biological invasions and encroachment, and climate warming. As part of an international Plant Functional Traits Course we collected comprehensive trait data in five sites along an elevation gradient from 2,000–2,800 m a.s.l. and in a climate warming experiment at 3,064 m a.s.l. in the Maloti-Drakensberg, South Africa. We sampled 24,405 aboveground and 94 root trait measurements from 171 vascular plant taxa paired with 11 other datasets reflecting vegetation and structure, leaf and ecosystem carbon and water fluxes, leaf hyperspectral reflectance, and microclimatic and environmental data. Our data provide the first recorded trait data for 47 vascular plant species and more than double the trait data coverage from the Maloti-Drakensberg (106% increase). This study offers insights into plant and ecosystem functioning, provides a baseline for assessing impacts of environmental change, builds local competence, and aligns with similar data from China, Svalbard, Peru, and Norway.

Plant‐fungal associations are shaped by both abiotic and biotic variables, but how abiotic variables influence the pool of available fungal species has been much more studied than how the abiotic environment structures the complex and dynamic associations between a host plant and its associated fungi. The question of whether plant‐associated fungal communities are primarily driven by fungal species availability or by the effects of the abiotic conditions on the type and strength of the association remains unclear. Here, a large‐scale field survey in Fennoscandia investigated how the selected fungal communities within different Bistorta vivipara plant compartments (bulbils, leaves and roots) varied with altitude, relative to the available fungal species pool in the soil and surrounding plants. Our results revealed that while the selected fungal species pool was largely determined by the available fungal species pool, the occurrence probability of some fungal species increased at high or low altitudes relative to the respective available fungal species pool. Furthermore, while we found that plant compartment was a major selective force shaping plant‐fungal associations, environment‐driven selection influenced the type and strength of plant‐fungal associations. While the fungi present in the environment largely determined which fungi associated with the focal plants, the type and strength of fungal species associations changed depending on the altitude‐related abiotic stressors imposed on the plant, such as lower temperatures, shorter growing seasons and high winds. Synthesis. Whether plants associate with fungal species just from the available fungal pool or differentially depending on the environmental stressors imposed on the plant, is not well understood, yet this is central for understanding both plant and microbial assembly. We conclude that plant‐fungal associations at different altitudes are not exclusively shaped by passive responses to fungal species availability but rather by more strategic responses by intensifying the associations with fungal species that may offer ecological advantages, such as improved productivity and health. These findings deepen our understanding of how plants adapt to environmental stress through selective symbiosis, with broader implications for plant‐fungal community assembly and ecosystem dynamics.

Low temperatures and nutrient limitation have shaped Arctic plant communities, which are now affected by biome‐wise changes in both climate and nutrient cycling. Rising temperatures are favouring taller plant species with more resource‐acquisitive traits across the Arctic tundra. Simultaneously, declines in seabird populations may reduce subsidies of marine‐derived nutrients to terrestrial ecosystems, potentially favouring more resource‐conservative plant traits. It is crucial to understand the consequences of these concurrent changes in climate and marine‐derived nutrient inputs from seabirds for the functional composition and roles of Arctic plant communities. We use a 'space‐for‐time approach' to compare the functional composition of vascular plant communities across two elevational gradients in High Arctic Svalbard, one where climate is the major environmental driver and one influenced by nutrient input from a seabird colony. We assess changes in 13 traits related to plant size, leaf economics and nutrient cycling along the two gradients, and we also explore the relative contributions of species turnover and intraspecific variation to total trait variation across and between the gradients. Elevation per se had little impact on the plant functional composition. Instead, plants at the top of the seabird nutrient gradient, closest to the nesting sites, were taller and had resource‐acquisitive trait values, such as larger and thicker leaves and higher leaf nutrient contents. Enriched soil δ 15 N‰ signatures at these sites correlated with resource‐acquisitive values of leaf area, specific leaf area, leaf dry matter content, leaf phosphorous content and with enriched leaf δ 15 N‰ signatures. This variation in leaf economic traits and isotopes was largely driven by intraspecific variation at the nutrient gradient, whereas species turnover dominated at the reference gradient. Our results are consistent with marine‐derived nutrient subsidies from seabirds being a major driver of functional trait variation in Arctic vegetation. Ongoing declines in seabird populations may therefore affect terrestrial primary producer communities in the Arctic and beyond, with potentially important but unknown implications for biodiversity, consumer and decomposer communities, and ecosystem processes. Read the free Plain Language Summary for this article on the Journal blog.

Accurate methane (CH 4 ) emission estimates from Arctic and boreal wetlands are essential for reducing global budget uncertainties but are hindered by poorly constrained wetland distribution and classification. We assessed how land cover map resolution and thematic detail influence these estimates. Using very high spatial resolution land cover maps (≤2.5 m) with five to seven harmonized classes and 4–50% wetland coverage, we estimated CH 4 emissions across seven Arctic and boreal sites in North America and Eurasia. Resampling to coarser resolutions (up to 5 km) revealed that CH 4 flux estimates remained within 13% error when resolution was ≤25 m pixel size. At resolutions coarser than 1 km, four of seven sites shifted from net CH 4 source to sink, due to misrepresentation of wetland extent in heterogeneous landscapes with small, fragmented wetlands. Thematic detail also proved critical, as fens—high CH 4 emitters—were disproportionately underrepresented in coarse (>1 km) maps relative to other wetland types. We also show that existing global or circumpolar land cover maps tend to misrepresent wetlands, either overlooking smaller features or overestimating coverage in wetland dominated areas. Our findings indicate that coarse-scale land cover datasets are unsuitable for estimating CH 4 budgets in these regions, where high spatial resolution and biogeochemically relevant land cover classes are essential for reliable CH 4 emission upscaling.

Across the world, human (anthropophonic) sounds add to sounds of biological (biophonic) and geophysical (geophonic) origin, with human contributions including both speech and technophony (sounds of technological devices). To characterize society's contribution to the global soundscapes, we used passive acoustic recorders at 139 sites across 6 continents, sampling both urban green spaces and nearby pristine sites continuously for 3 years in a paired design. Recordings were characterized by bird species richness and by 14 complementary acoustic indices. By relating each index to seasonal, diurnal, climatic and anthropogenic factors, we show here that latitude, time of day and day of year each predict a substantial proportion of variation in key metrics of biophony-whereas anthropophony (speech and traffic) show less predictable patterns. Compared to pristine sites, the soundscape of urban green spaces is more dominated by technophony and less diverse in terms of acoustic energy across frequencies and time steps, with less instances of quiet. We conclude that the global soundscape is formed from a highly predictable rhythm in biophony, with added noise from geophony and anthropophony. At urban sites, animals experience an increasingly noisy background of sound, which poses challenges to efficient communication.

The links between intraspecific trait variation and community assembly remain little studied, partially due to the lack of statistical methods to jointly model intraspecific trait variation and species abundances at the community level. Here, we extend the joint species distribution modeling (JSDM) framework into the joint species-trait distribution modeling (JSTDM) framework to explicitly link species abundances to phenotypic variation in traits for multiple species simultaneously. Using a case study of 65 tundra plant species abundances and 3 key functional traits measured across 325 sites, we show how the JSTDM approach (1) estimates the statistical associations among species abundances, species-level traits, and site-level traits, relative to environmental variation; (2) improves predictions on trait variation by using information on species abundances; and (3) generates hypotheses about trait-driven community assembly mechanisms. The JSTDM methodology presented in this study allows assessing the interplay between species abundances and traits at the community level, providing the much needed modeling tools to quantify the role of phenotypic trait variation in eco-evolutionary community assembly.

Aim: Climate change is driving species towards higher elevations. While local shifts in elevation are well documented, patterns across entire mountain regions are less understood. On a local scale, abiotic factors, such as topography and solar radiation relating to microclimate, affect species distributions and can thus influence the rate of elevational shifts on mountain slopes. The impact of abiotic factors on biodiversity is evident, but range shift studies have mostly focused on groups of species with low mobility, such as plants. Location: Across European mountain regions of the Alps, Pyrenees, Scandinavia and the United Kingdom. Time Period: 2001-2021. Major Taxa Studied: One hundred seventy-seven bird species. Methods: We adopted a cross-scale community approach using abundance data to quantify the impact of the amount of solar radiation (measured as potential incoming solar radiation) on the mean elevational distribution and rate of elevational shifts of bird species in four European mountain regions. We modelled the impact of the amount of solar radiation using generalised linear mixed models. Results: We found that bird species inhabit higher elevations in areas receiving more solar radiation. We also found that the mean elevations at which species occur moved uphill by 0.5 m/year between the periods 2001-2004 and 2018-2021 across Europe. However, this rate of elevational shifts was similar between areas receiving low, medium and high amounts of solar radiation. We observed variations in the rate of elevational shifts that were fastest in Scandinavia and the Alps, while no uphill shift was observed in the UK or the Pyrenees. Main Conclusions: Our findings underscore the significance of abiotic factors, including solar radiation and climate change, driving, directly or indirectly, birds' elevational distributions. They also unveil consistent patterns of uphill shifts across different solar radiation regimes at a continental scale.

ABSTRACTMicroclimate measurements are crucial for explaining and predicting functions and patterns in nature, yet the availability of microclimate data often poses a challenge. This study introduces a dataset comprising 63 spatially continuous microclimate surfaces for the Kilpisjärvi region in northwestern Finland. The study region is a biodiversity hotspot for arctic-alpine flora and fauna and one of the most extensively investigated regions in Northern Europe. The data were gathered through a collaborative network of microclimate loggers, encompassing 430 measurement locations that comprehensively cover the 300 km2 landscape under study. We employed predominantly well-performing Random Forest models to project microclimate variables across the study area at a 3-metre spatial resolution. The high-resolution and extensive spatial coverage of the dataset facilitates examination of microclimate characteristics and variability across this sub-Arctic region, providing a valuable resource for both theoretical and applied research, as well as for biodiversity conservation.