Functional traits can vary in response to tree species mixing, which in turn might influence biomass production and, consequently, carbon (C) sequestration in diverse forests. However, evidence for consistent broad-scale patterns in tree trait responses, particularly regarding trait identity and their contribution to above-ground biomass outcomes, remains limited. Using data from even-aged forest stands in 11 tree diversity experiments in Europe and Brazil, encompassing 40 tree species, we estimated the influence of species mixing on above-ground biomass components (woody, litterfall and understory biomass), as well as effects of mixing on plasticity-driven changes in species- and community-level functional traits. At the community level, specific leaf area (SLA) and leaf area index (LAI) were higher in mixtures than expected values based on monocultures, while leaf nitrogen per area decreased, and leaf nitrogen per mass remained stable. SLA increases were primarily due to the response of less dominant tree species. Woody and litterfall biomass increased in mixtures, whereas understory biomass remained unchanged. At the species level, diversity-driven plastic changes were observed in multiple traits, but only SLA showed a consistent shift across species. Tree diversity effects on above-ground biomass were influenced by both functional diversity and diversity-driven trait shifts, where increased SLA and LAI enhanced woody biomass accumulation, while higher LAI in diverse stands reduced understory biomass. Together, these results show that tree species mixing alters canopy structure and light-related traits, with shifts in SLA and LAI constituting key pathways through which mixed forests accumulate more woody biomass.Read the free for this article on the Journal blog.

Aim Warming of the climate system is increasing the dominance of warm-adapted species, a process referred to as thermophilisation. In forests, adult trees in the forest canopy experience warmer daytime summer conditions than juveniles in the understorey, but they are less susceptible to warming. These differences can result in differing thermophilisation rates between adults and juveniles. Here, we quantify for the first time the long-term thermophilisation of tree species in temperate European forests, comparing adults with juveniles.Location Europe.Methods We calculated the thermophilisation of adults and juveniles of forest tree species using layer-specific climatic data, species cover and occurrence data from 2202 resurveyed vegetation plots recorded twice between 1933 and 2017 and located across 12 European countries. We inferred species' thermal profiles from species distribution maps matched to gridded open-air temperature (proxy for above-canopy macroclimate) for adults and to below-canopy microclimate temperature for juveniles.Results The thermophilisation rate in the juvenile layer was seven times higher than in the adult tree layer. The thermophilisation rates of both adults and juveniles were primarily driven by gains in relatively warm-adapted species and a concurrent, but less strong, decrease in cold-adapted species.Conclusion The compositional change in favour of more warm-adapted species was mainly driven by gains in warm-adapted species. The magnitude of these responses and the influencing variables were different in the community of adults and juveniles. These results underpin the importance of separately quantifying the responses of individuals throughout their life cycle to improve our ability to understand the impacts of environmental change on forest biodiversity and composition and apply targeted management actions.

Forest structural complexity is widely assumed to enhance biodiversity, yet its effects on the physiological condition and health of individual organisms remain poorly understood. We examined how forest structural complexity relates to individual condition and, in turn, to ectoparasite and pathogen occurrence in free-living vertebrates. Across 19 temperate forest plots in Flanders (northern Belgium), spanning a gradient of structural complexity, we sampled birds and small mammals and quantified individual condition using scaled mass index, fluctuating asymmetry, and relative telomere length. Larval ticks were collected from hosts and screened for a broad panel of tick-borne pathogens. Relative telomere length tended to be lower in more structurally complex forests, whereas body condition and fluctuating asymmetry showed no consistent relationship with forest structure. Individuals in better body condition were less likely to carry larval ticks. In contrast, hosts with shorter telomeres were more likely to carry pathogen-infected larvae, consistent with links between cumulative physiological stress and infection susceptibility. No evidence was found for systematic co-occurrence among pathogens within larval ticks. Together, our results indicate that individuals interact with forest structure through multiple, potentially independent physiological pathways, shaping observed patterns of parasite load and tick-borne pathogen prevalence.

Increasing forest structural complexity is a key objective of future-proof forest management, with benefits for biodiversity. However, empirical evidence for generalizable biodiversity-structure relationships across taxa is still limited. We investigated whether structurally more complex forests support greater species richness within individual taxa and higher multidiversity (i.e. a composite diversity metric) across taxonomic and functional groups in 19 mature forest plots in Flanders, Belgium. As one of the most densely populated regions in Europe, Flanders provides a realistic and policy-relevant context to test structure-biodiversity relationships, despite not capturing old-growth forest conditions. Its forests, often dominated by a few tree species and subject to long-term anthropogenic pressures and management, represent a realistic gradient of structural complexity. Structural complexity was quantified using a Structural Complexity Index (SCI), and biodiversity was assessed using a multidiversity index integrating scaled species richness across five taxonomic and seven arthropod functional groups, as well as the species richness of individual groups. Using mixed-effects models and multivariate Bayesian analyses, we tested both direct effects of SCI on biodiversity and the covariation in species richness among groups. Contrary to expectations, SCI was not a consistent predictor of multidiversity, and most groups showed weak or inconsistent responses. These findings might suggest that, within the range of structural complexity currently present in managed forests, structural complexity alone may be insufficient to enhance biodiversity in simplified forests.

Climate warming is shifting biological communities, with warmth-demanding species being favoured at the expense of cold-adapted species in a process referred to as thermophilization1-4. Because biodiversity responses often lag behind climate warming, climatic debts are accumulating in many ecosystems across the world5-7. Although we might expect that thermophilization and climatic debts will vary among habitats, standardized quantification across ecosystems is lacking. Here we analysed multidecadal data from 6,067 resurveyed vegetation plots over 12-78 years in forests, grasslands and on alpine summits across Europe. We demonstrate that forest understory and grassland plant communities experienced positive thermophilization, although not significantly different from zero. By contrast, alpine summit vegetation showed much stronger (up to five times) and significant thermophilization. Thermophilization was driven largely by increases in warmth-demanding species in grasslands, by declines in cold-adapted species on alpine summits and by both processes in forests. Significant climatic debts have accumulated in forests and alpine summits, but less so in grasslands, with debts positively correlated with macroclimate temperature changes. Our findings uncover divergent thermophilization trajectories and increasing climatic debts across ecosystems. Moreover, we highlight the mechanisms that enable some communities to track climate change more closely than others and provide a basis for projecting future shifts in plant communities under accelerating climate warming.

Aim: Rapid warming across the tundra biome is driving widespread changes in vascular plant community composition. While species turnover is well-documented, the ramifications for tundra functional diversity are unknown. Here, we quantify biome-scale spatial gradients and temporal trends in the functional diversity of tundra vegetation for the first time. Location: A biome-scale synthesis of in situ vegetation surveys and resurveys from 2087 plots across 45 sites throughout the high-latitude tundra. Time Period: 1984-2022 Major Taxa Studied: 352 vascular plant species encompassing shrub, graminoid and forb functional groups Methods: We used tundra species trait data alongside long-term, plot-based sampling of species composition to estimate three functional diversity metrics: functional richness, functional evenness and functional dispersion. We used Bayesian mixed-models to test for latitudinal gradients in functional diversity, temporal trends in functional diversity and major abiotic and biotic correlates of functional diversity over space and time. Results: Mirroring biogeographic gradients in species diversity, functional richness declined at high latitude and colder sites. However, functional richness exhibited no net directional change across the three-decade study period. Plots dominated by single growth forms had reduced functional diversity when compared with plots where individual growth forms had intermediate abundance. Changes in temperature and precipitation were not linked to temporal changes in functional diversity. Where shrubs were increasing in abundance, functional richness and dispersion declined, whereas increases in forbs were accompanied by increases in both aspects of functional diversity. Main Conclusions: The functional diversity of tundra plants is currently lowest in colder and high latitude sites. Despite rapid warming of the tundra biome, we have yet to see broad-scale changes in functional diversity over time. However, where shrubification occurs, we anticipate accompanying reductions in functional diversity. Our results highlight the potential consequences of changes in tundra species composition for ecosystem functioning over the coming decades.

Ticks play a significant role in the transmission of various pathogens, impacting both human and animal health. Understanding the factors influencing tick feeding preferences is crucial for mitigating the risk of tick-borne diseases. This study investigates the blood preference of Ixodes ricinus nymphs, focusing on host species, stress hormone levels (glucocorticoids), and the presence of Borrelia burgdorferi s.l. bacteria. We conducted three series of in vitro experiments using a setup where individual blood drops (15 μl) were placed on filter paper over a 37 °C plate. Ticks were placed in the center, and their movements were tracked for 2 min to record preferences. The first experiment tested preferences for blood from different hosts (mouse, bird, sheep). The second examined the role of stress hormones by offering blood with varying levels of added cortisol and corticosterone (0, 10, 100, 1000 ng/ml). The third experiment investigated the potential influence of Borrelia infection, combined with elevated stress hormone levels, on blood preference. Our results show that I. ricinus nymphs preferred blood without added glucocorticoids and, in mice, blood with Borrelia infection. No clear preference for a specific host species was observed. These findings offer insights into how host physiological state may affect tick host selection, even though I. ricinus may not always have the opportunity to choose between hosts. Future studies should explore these interactions in more biologically relevant models to better understand the dynamics of tick attachment and feeding. Unraveling these mechanisms could aid in developing new strategies to control tick-borne diseases.

Forests provide crucial habitats for nature and people, but also harbour organisms, such as ticks, that can act as vectors for pathogens. Understanding how forest management practices influence host-parasite-pathogen interactions is essential for promoting both forest biodiversity conservation and nature's contributions to people. This study investigates the complex relationships between forest structural complexity, body condition, and tick infestation probability in a common forest bird, the great tit (Parus major), across 19 forests in the Flemish Ardennes, Belgium. Using Structural Equation Modeling (SEM), we first integrated multiple phenotypic health proxies into a single overall condition index. Subsequently, we assessed how variations in forest structural complexity impact the condition of forest birds and their chances of contracting ticks. Our findings showed that birds in better physiological condition, as indicated by lower levels of cellular stress, were more likely to carry ticks. This may be due to ticks preferring healthier and more nutritious hosts and/or condition-linked differences in bird behaviour (e.g. foraging), resulting in higher contact rates with ticks. While forest structural complexity did not significantly affect the birds' overall body condition, it was responsible for an increased tick infestation probability. Specifically, forests with higher structural complexity were associated with increased densities of questing nymphs, thereby elevating the risk of tick infestation in birds. This study highlights the multifaceted role of forest structural complexity in shaping host-parasite dynamics. These insights are valuable for developing forest policies that balance the enhancement of ecological health with the mitigation of health risks posed by tick-borne diseases.

Forest structural complexity influences arthropod communities by shaping habitat availability, microclimatic conditions, and resource distribution. However, the extent to which structural complexity and specific structural components drive arthropod abundance and biomass remains poorly understood in temperate forests. This study examined how local and landscape-scale forest characteristics influence arthropod communities across vertical strata (forest floor (FF), herb layer (HL), and shrub layer (SL)) in 19 temperate deciduous forests in Belgium, dominated by pedunculate oak, European beech, or Canadian poplar. At the local scale, we assessed dominant tree species identity, overall forest structural complexity, and its components (vertical and horizontal structure, woody layer, herbal layer, and deadwood). At the landscape scale, we evaluated forest area, edge length, forest cover, and vegetation greenness (normalized difference vegetation index (NDVI)). Contrary to expectation, arthropod biomass and abundance did not consistently increase with higher structural complexity. Instead, woody layer complexity, dominant tree species, and NDVI emerged as key drivers, with effects varying by context and stratum. Arthropod abundance and biomass were the highest in oak- and poplar-dominated forests and the lowest in beech forests, likely due to differences in litter quality, microhabitat availability, and understory development. Woody layer complexity positively influenced forest floor arthropods in poplar forests but had a negative effect in oak forests. At the landscape scale, NDVI unexpectedly showed negative relationships with arthropod abundance across strata and with arthropod biomass in the herb layer, likely reflecting dense canopy suppression of understory productivity. Arthropod biomass on the forest floor increased with forest cover, while abundance in the shrub layer decreased with forest cover but increased with forest area. These findings highlight the complex interplay between forest structural attributes, dominant tree species, and landscape factors in shaping arthropod communities. By identifying the key drivers of arthropod abundance and biomass, this study contributes to a better understanding of biodiversity patterns in temperate forests and their ecological dynamics.

Mixed-species forestry is a promising approach to enhance productivity, increase carbon sequestration, and mitigate climate change. Diverse forests, composed of species with varying structures and functional trait profiles, may have higher functional and structural diversity, which are attributes relevant to a number of mechanisms that can influence productivity. However, it remains unclear whether the context-dependent roles of functional identity, functional diversity, and structural diversity can lead to a generalized understanding of tree diversity effects on stand productivity. To address these gaps, we analyzed growth data from 83,600 trees from 89 species across 21 young tree diversity experiments spanning five continents and three biomes. Results revealed a positive saturating relationship between tree species richness and stand productivity, with reduced variability in growth rates among more diverse stands. Structural equation modeling demonstrated that functional diversity mediated the positive effects of species richness on productivity. We additionally report a negative relationship between structural diversity and productivity, which decreased with increasing species richness. When partitioning net diversity effects, we found that selection effects played a dominant role in driving the overall increase in productivity in these predominantly young stands, contributing 77% of the net diversity effect. Selection effects increased with diversity in wood density. Furthermore, acquisitive species with lower wood density and higher leaf nitrogen content had higher productivity in more diverse stands, while conservative species showed neutral to slightly negative responses to species mixing. Together, these results suggest that combining acquisitive with conservative species allows acquisitive species to drive positive selection effects while conservative species tolerate competition. Thus, contrasting resource-use strategies can enhance productivity to optimize mixed-species forestry, with potential for both ecological and economic benefits.

More and more forest management focuses on increasing structural complexity to improve environmental conditions for biodiversity and forest functioning. However, it remains uncertain whether animal populations also benefit from increased forest structure. Small mammals are key reservoirs for zoonotic diseases, so understanding how forest structure changes their condition and how this, in turn, affects infection dynamics is critical for animal and human health. This study examined relationships between forest structural complexity, individual body condition (scaled mass index (SMI) and telomere length), pathogen prevalence, and tick load in bank voles and wood mice across 19 forest plots in northern Belgium, representing a gradient of structural complexity. Results showed that higher forest complexity, especially with more dead wood and a well-developed herb layer, increased small mammal abundance. Density varied by tree species, with highest abundances in oak and lowest in poplar forests. In addition, body condition improved with structural complexity; SMI increased with woody layer complexity in wood mice and with dead wood availability in bank voles. No clear relationship between telomere length and forest complexity was observed. The relationship between body condition and pathogen prevalence was species- and pathogen-specific. Small mammals in better body condition were more likely to host Borrelia burgdorferi (causing Lyme disease), particularly in complex forests, indicating a higher infection risk with increasing structural complexity. Forest management practices that aim to enhance forest structure and biodiversity may thus inadvertently increase zoonotic disease risk and should take these findings in consideration to minimize the risk for human health.

The Arctic is warming four times faster than the global average1 and plant communities are responding through shifts in species abundance, composition and distribution2-4. However, the direction and magnitude of local changes in plant diversity in the Arctic have not been quantified. Using a compilation of 42,234 records of 490 vascular plant species from 2,174 plots across the Arctic, here we quantified temporal changes in species richness and composition through repeat surveys between 1981 and 2022. We also identified the geographical, climatic and biotic drivers behind these changes. We found greater species richness at lower latitudes and warmer sites, but no indication that, on average, species richness had changed directionally over time. However, species turnover was widespread, with 59% of plots gaining and/or losing species. Proportions of species gains and losses were greater where temperatures had increased the most. Shrub expansion, particularly of erect shrubs, was associated with greater species losses and decreasing species richness. Despite changes in plant composition, Arctic plant communities did not become more similar to each other, suggesting no biotic homogenization so far. Overall, Arctic plant communities changed in richness and composition in different directions, with temperature and plant-plant interactions emerging as the main drivers of change. Our findings demonstrate how climate and biotic drivers can act in concert to alter plant composition, which could precede future biodiversity changes that are likely to affect ecosystem function, wildlife habitats and the livelihoods of Arctic peoples5,6.

We face increasing concerns about how the local diversity of native plant communities responds to various drivers of global change, yet often lack comprehensive studies that integrate several components of diversity and the effects of both local and regional drivers of change. We analyzed changes in taxonomic, functional, and phylogenetic diversity across 2681 (semi-)permanent temperate forest understory plots surveyed and resurveyed for all vascular plants over intervals of 15-78 yr, spanning 72 regions distributed across Europe. We quantified temporal changes in these diversity indices and assessed their responses to changes in both local drivers (plot-level overstory cover, indicator values for soil nutrients) and regional shifts in macroclimate and nitrogen deposition. Overall, local changes in taxonomic, functional, and phylogenetic diversity were centered around zero, reflecting - on average - little net change in forest diversity. Observed diversity changes mostly reflected local conditions such as overstory cover change and baseline soil nutrients rather than regional drivers of large-scale change. Changes in phylogenetic diversity correlated positively with changes in taxonomic diversity but negatively with changes in functional diversity. Our findings underscore the importance of local habitat management and multifaceted diversity monitoring for effective biodiversity conservation in temperate forests.

We need urgent conservation efforts to curb global amphibian declines. Individual indicators provide valuable insights into how amphibian populations respond to different management practices. We compared body condition and fluctuating asymmetry of individual alpine newts (Ichthyosaura alpestris) from ten populations across a gradient of both terrestrial and aquatic structural habitat complexity. Newt body condition was better in ponds surrounded by a greater proportion of forest (P <0.001, estimate f SE = 0.46 f 0.11). Moreover, newts in such ponds were more symmetrical than conspecifics in ponds surrounded by less forest (P <0.01, estimate f SE = -0.25 f 0.09). Neither structural complexity of ponds nor the complexity of the terrestrial environment had a significant impact on alpine newt body condition and fluctuating asymmetry. Our findings suggest a sufficient proportion of forest adjacent to the breeding habitat is important in sustaining adult condition of a common semi-aquatic amphibian.

Mixed-species forests are proposed to enhance tree resistance and resilience to drought. However, growing evidence shows that tree species richness does not consistently improve tree growth responses to drought. The underlying mechanisms remain uncertain, especially under unprecedented multiyear droughts. We used a network of planted tree diversity experiments to investigate how neighborhood tree diversity and species' functional traits influence individual tree responses to drought. We analyzed tree cores (948 trees across 16 species) from nine young experiments across Europe featuring tree species richness gradients (1-6 species), which experienced recent severe droughts. Radial growth response to drought was quantified as tree-ring biomass increment using X-ray computed tomography. We applied hydraulic trait-based growth models to analyze single-year drought responses across all sites and site-specific responses during consecutive drought years. Growth responses to a single-year drought were partially explained by the focal species' hydraulic safety margin (representing species' drought tolerance) and drought intensity, but were independent of neighborhood species richness. The effects of neighborhood functional diversity on growth responses shifted from positive to negative with increasing drought duration during a single growing season. Tree diversity effects on growth responses strengthened during consecutive drought years and were site-specific with contrasting directions (both positive and negative). This indicates opposing diversity effects pathways under consecutive drought events, possibly resulting from competitive release or greater water consumption in diverse mixtures. We conclude that tree diversity effects on growth under single-year droughts may differ considerably from responses to consecutive drought years. Our study highlights the need to consider trait-based approaches (specifically, hydraulic traits) and neighborhood scale processes to understand the multifaceted responses of tree mixtures under prolonged drought stress. This experimental approach provides a robust framework to test biodiversity-ecosystem functioning (BEF) relationships relevant for young, planted forests under increased drought stress.

Global changes are forcing forest management toward more resilient and more structurally complex forests, thereby creating a more attractive habitat for their associated biodiversity. However, the assessment of forest structural complexity and its relation to biodiversity is challenging. In this work, we applied the structural complexity index (SCI), which is designed for forest managers to quickly and easily assess structural complexity. Studies comparing the predictive value of this index with taxonomic biodiversity monitoring are rare. Herein, we focus on wild pollinators, which could potentially benefit from this shift toward more structurally complex forests. We used elevated pan traps in 19 forest plots varying in structural complexity and dominant tree species to address the following aims: First, we investigated how predictive the SCI is for wild bee and syrphid abundance and diversity. Second, we studied their communities and how these could be shaped by the SCI. We found that the SCI was not predictive for either the abundance or diversity. We found that some tree species exhibit effects on abundance and diversity, stressing the importance of maintaining multiple tree species. However, no differences between wild pollinator communities among different forest types and SCI levels were observed. Our results show that tools such as the SCI, which allows forest managers to quickly assess the potential biodiversity of forest stands, are not necessarily predictive for each taxonomic group. However, combining collection methods across multiple years and taxonomic groups should provide additional insight for an overall assessment of the predictive value of the SCI for pollinators in forests.

1. Wild pollinators are crucial for ecosystem functioning and human food production and often rely on floral resources provided by different (semi-) natural ecosystems for survival. Yet, the role of European forests, and especially the European forest herb layer, as a potential provider of floral resources for pollinators has scarcely been quantified. 2. In this study, we measured the potential nectar production (PNP) of the forest herb layer using resurvey data across 3326 plots in temperate forests in Europe, with an average time interval of 41 years between both surveys in order to assess (i) the importance of the forest herb layer in providing nectar for wild pollinators, (ii) the intra-annual variation of PNP, (iii) the overall change in PNP between survey periods and (iv) the change in intra-annual variation of PNP between sur-vey periods. The PNP estimates nectar availability based on the relative cover of different plant species in the forest herb layer. Although PNP overestimates actual nectar production, relative differences amongst plots provide a valid and informative way to analyse differences across time and space. 3. Our results show that the forest herb layer has a large potential for providing nec-tar for wild pollinator communities, which is greatest in spring, with an average PNP of almost 16 g sugar/m2/year. However, this potential has drastically declined (mean plot- level decline >24%). 4. Change in light availability, associated with shifts in canopy structure and canopy composition, is the key driver of temporal PNP changes. 5. Synthesis. Our study shows that if management activities are carefully planned to sustain nectar- producing plant species for wild pollinators, European forest herb layers and European forests as a whole can play key roles in sustaining wild pol-linator populations.

Predicting forest understorey community responses to global change and forest management is vital given the importance of the understorey for biodiversity conservation and forest functioning. Though substantial effort has gone into disentangling the impact of global change on understorey communities, scarcity of information on sitespecific environmental drivers across large temporal-spatial scales has limited our ability to predict global change effects at specific forest sites. In this study, using vegetation resurvey and soil data from 1363 plots across temperate Europe, we applied a machine learning approach (gradient boosting regression, GBR) to model and predict site-specific responses of four understorey properties to global change. We applied our final GBR models at 8 forest sites in Austria to validate the model performance, predict understorey trajectories, and evaluate the effect of alternative scenarios for future nitrogen(N) deposition, climate change and forest management on the projected trajectories. Our results showed that the R2 value of the four final GBR models on the independent testing dataset ranged between 0.611 and 0.723 and the most important environmental drivers in predicting the trajectory of understorey properties at specific forest sites were soil pH, soil total carbon-to-nitrogen ratio, overstorey shade-casting ability and regional-scale mean annual precipitation. The out-of-sample R2 value of the four final GBR models on the Austrian data ranged between 0.224 and 0.561. The forecasted trajectories for the Austrian forest sites showed that site-specific understorey responses to near-future climate warming were expected to be weak. Under N deposition decreases, the proportion of woody species was predicted to increase, while species richness and total vegetation cover were predicted to decrease. Furthermore, under a closed canopy, the understorey community was predicted to shift towards more woody species and more forest specialists, albeit with reduced species richness and vegetation cover. Given expected warming and declining N

Plant communities are being exposed to changing environmental conditions all around the globe, leading to alterations in plant diversity, community composition, and ecosystem functioning. For herbaceous understorey communities in temperate forests, responses to global change are postulated to be complex, due to the presence of a tree layer that modulates understorey responses to external pressures such as climate change and changes in atmospheric nitrogen deposition rates. Multiple investigative approaches have been put forward as tools to detect, quantify and predict understorey responses to these global-change drivers, including, among others, distributed resurvey studies and manipulative experiments. These investigative approaches are generally designed and reported upon in isolation, while integration across investigative approaches is rarely considered. In this study, we integrate three investigative approaches (two complementary resurvey approaches and one experimental approach) to investigate how climate warming and changes in nitrogen deposition affect the functional composition of the understorey and how functional responses in the understorey are modulated by canopy disturbance, that is, changes in overstorey canopy openness over time. Our resurvey data reveal that most changes in understorey functional characteristics represent responses to changes in canopy openness with shifts in macroclimate temperature and aerial nitrogen deposition playing secondary roles. Contrary to expectations, we found little evidence that these drivers interact. In addition, experimental findings deviated from the observational findings, suggesting that the forces driving understorey change at the regional scale differ from those driving change at the forest floor (i.e., the experimental treatments). Our study demonstrates that different approaches need to be integrated to acquire a full picture of how understorey communities respond to global change.