Discovering how species' thermal limits evolve and vary spatially is crucial for predicting their vulnerability to ongoing environmental warming. Current evidence indicates that heat tolerance is less spatially variable than cold tolerance among species, presenting a major concern for organismal vulnerability in a rapidly warming world. This asymmetry in thermal limits has been supported by large-scale geographic studies, across latitudinal and elevational gradients (known as Brett's heat-invariant rule). Yet, how critical limits vary across finer spatial scales (e.g., across microenvironments) is less understood. Here, we show that minimum temperatures are more variable than maximum temperatures at large geographic scales (across latitude/elevation) but are less variable at local scales (within sites), in turn guiding spatial asymmetries in thermal tolerances. Using thermal tolerance measurements from amphibians, insects, and reptiles, we confirm the invariance of heat tolerance at large spatial scales and also find more variable heat than cold tolerances at local scales (an inverted Brett's heat-invariant rule at fine spatial scales). Our results suggest that regional- or global-level studies will likely obscure fine-scale structuring in thermal habitats and corresponding patterns of local heat tolerance adaptation. We emphasize that inferences based on broadscale geographic patterns obscure fine-scale variation in thermal physiology. For instance, a genetic basis for fine-scale variation in thermal physiology may reshuffle spatial and phylogenetic patterns of vulnerability.
- Klíčová slova
- Brett's heat‐invariant rule, elevation, latitude, local scale, macrophysiology, microclimate, spatial scales, amphibians, reptiles, insects, thermal tolerance limits,
- MeSH
- biologické modely MeSH
- ekosystém MeSH
- hmyz * fyziologie MeSH
- obojživelníci * fyziologie MeSH
- plazi * fyziologie MeSH
- vysoká teplota * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Biodiversity loss poses a significant threat to ecosystem functioning. However, much of the empirical evidence for these effects is based on artificial experiments that often fail to simulate the structure of natural communities. Hence, it is still unclear whether natural diversity losses would significantly affect the functioning of "real-world" ecosystems. As subordinate and rare species constitute most of the diversity in natural communities and are often more vulnerable to local extinction, we evaluated their contribution to ecosystem functioning in a naturally species-rich grassland. We focused on two mechanisms by which they can support ecosystem functions: redundancy and complementarity. We conducted two long-term field experiments (>6 years) simulating contrasting biodiversity loss scenarios through the manual removal of plant species and measured the consequences of species loss on various ecosystem functions related to carbon dynamics. The latter were examined seasonally to explore diversity effects outside the typical peak of vegetation. We found that dominant removal led to substantial reductions in aboveground phytomass and litter production and altered the annual carbon fixation capacity of the vegetation, highlighting the pivotal role of dominant species in driving ecosystem functioning. Despite high species diversity, other species could not fully compensate for the loss of a single dominant even after more than 25 years, challenging assumptions about redundancy. Complementarity effects were not detected at the peak of vegetation but were evident in early spring and autumn when subordinate and rare species enhanced ecosystem functions. Surprisingly, belowground phytomass, soil organic carbon content, and litter decomposition were unaffected by species removal, suggesting complex interactions in belowground processes. These findings underscore the importance of dominant species in maintaining ecosystem functioning and emphasize the need for nuanced approaches to studying biodiversity loss in real-world communities. Comprehensive seasonal measurements are essential for accurately discerning the effects of biodiversity on ecosystem dynamics and informing effective conservation strategies that maintain ecosystem functioning.
- Klíčová slova
- aboveground biomass, belowground biomass, biodiversity loss, dominant species, ecosystem functioning, litter decomposition, net ecosystem C exchange, phenological complementarity, seasonal carbon dynamics, soil organic carbon,
- MeSH
- biodiverzita * MeSH
- časové faktory MeSH
- koloběh uhlíku * MeSH
- pastviny * MeSH
- roční období * MeSH
- rostliny * klasifikace MeSH
- uhlík * metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- uhlík * MeSH
Clonal demographic traits play important roles in regulating community dynamics. Yet, it remains unclear how the responses of these clonal traits to drought might depend on previous drought exposure, and how drought responses vary among grasslands. We conducted a repeated drought experiment across four grasslands along an aridity gradient in northern China. We assessed the effects of single (precipitation reduction in 2021-2022) versus recurrent (precipitation reduction in 2015-2018 and 2021-2022) drought on bud density, shoot density, and the ratio of bud to shoot density. Drought reduced bud density at all grasslands and shoot density at most grasslands. Drought reduced the ratio of bud-to-shoot density only in the most arid grasslands. Recurrent drought had larger negative effects than a single drought on bud density and composition of bud and shoot at only one of four grasslands, and on shoot density at two of four grasslands. Our results suggest that previous drought exposure can alter the response of plant clonal demographic traits to subsequent drought in some but not all grasslands, and that responses can vary with mean climate.
- Klíčová slova
- bud limitation, climate change, drought frequency, population regeneration, productivity, shoot density,
- MeSH
- květy * fyziologie MeSH
- lipnicovité * fyziologie MeSH
- období sucha * MeSH
- pastviny * MeSH
- pouštní klima * MeSH
- výhonky rostlin * fyziologie růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Čína MeSH
Insectivorous predators, including birds and bats, play crucial roles in trophic cascades. However, previous research on these cascades has often relied on permanent predator exclosures, which prevent the isolation of specific effects of birds and bats, given their different activity patterns throughout the day. Moreover, limited knowledge exists regarding the variations in individual effects of these predators under different biotic and abiotic conditions, such as changes in elevation. To address these uncertainties, our study aimed to investigate the distinct effects of bats and birds on arthropod densities in foliage and herbivory damage in lowland and highland rainforests of Papua New Guinea (PNG). Predator exclosures were established for one month to exclude diurnal or nocturnal predators across 120 saplings (ca. 2.5-4 m tall) selected from two lowland and two highland forests (i.e., 30 saplings per study site) along the Mt. Wilhelm transect in PNG. Arthropods were collected and measured, and herbivory damage was analyzed at the end of the experiment. Birds significantly reduced arthropod densities by 30%, particularly in arthropods longer than 10 mm, regardless of elevation. Additionally, both birds and bats appeared to mitigate herbivory damage in highland forests, with protected saplings displaying up to 189% more herbivory. Our results support previous studies that have demonstrated the ability of insectivorous predators to reduce leaf damage through the control of arthropods. Furthermore, our approach highlights the importance and necessity of further research on the role of seasons and elevations in trophic cascades.
- Klíčová slova
- arthropod density, elevation, predator exclosures, top‐down control, trophic cascades, tropical forest,
- MeSH
- býložravci * fyziologie MeSH
- Chiroptera * fyziologie MeSH
- členovci fyziologie MeSH
- lesy * MeSH
- potravní řetězec MeSH
- predátorské chování fyziologie MeSH
- ptáci * fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Papua Nová Guinea MeSH
Global change is affecting the distribution and population dynamics of plant species across the planet, leading to trends such as shifts in distribution toward the poles and to higher elevations. Yet, we poorly understand why individual species respond differently to warming and other environmental changes, or how the trait composition of communities responds. Here we ask two questions regarding plant species and community changes over 42 years of global change in a temperate montane forest in Québec, Canada: (1) How did the trait composition, alpha diversity, and beta diversity of understory vascular plant communities change between 1970 and 2010, a period over which the region experienced 1.5°C of warming and changes in nitrogen deposition? (2) Can traits predict shifts in species elevation and abundance over this time period? For 46 understory vascular species, we locally measured six aboveground traits, and for 36 of those (not including shrubs), we also measured five belowground traits. Collectively, they capture leading dimensions of phenotypic variation that are associated with climatic and resource niches. At the community level, the trait composition of high-elevation plots shifted, primarily for two root traits: specific root length decreased and rooting depth increased. The mean trait values of high-elevation plots shifted over time toward values initially associated with low-elevation plots. These changes led to trait homogenization across elevations. The community-level shifts in traits mirrored the taxonomic shifts reported elsewhere for this site. At the species level, two of the three traits predicting changes in species elevation and abundance were belowground traits (low mycorrhizal fraction and shallow rooting). These findings highlight the importance of root traits, which, along with leaf mass fraction, were associated with shifts in distribution and abundance over four decades. Community-level trait changes were largely similar across the elevational and temporal gradients. In contrast, traits typically associated with lower elevations at the community level did not predict differences among species in their shift in abundance or distribution, indicating a decoupling between species- and community-level responses. Overall, changes were consistent with some influence of both climate warming and increased nitrogen availability.
- Klíčová slova
- abundance, biomass allocation, climate change, elevation, forest understory, functional diversity, functional traits, global change, nitrogen deposition, root traits, spatial gradients, temporal gradients,
- MeSH
- biomasa * MeSH
- časové faktory MeSH
- klimatické změny * MeSH
- kořeny rostlin * fyziologie MeSH
- rostliny * klasifikace MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- provincie Québec MeSH
An increasing number of studies of above-belowground interactions provide a fundamental basis for our understanding of the coexistence between plant and soil communities. However, we lack empirical evidence to understand the directionality of drivers of plant and soil communities under natural conditions: 'Are soil microorganisms driving plant community functioning or do they adapt to the plant community?' In a field experiment in an early successional dune ecosystem, we manipulated soil communities by adding living (i.e., natural microbial communities) and sterile soil inocula, originating from natural ecosystems, and examined the annual responses of soil and plant communities. The experimental manipulations had a persistent effect on the soil microbial community with divergent impacts for living and sterile soil inocula. The plant community was also affected by soil inoculation, but there was no difference between the impacts of living and sterile inocula. We also observed an increasing convergence of plant and soil microbial composition over time. Our results show that alterations in soil abiotic and biotic conditions have long-term effects on the composition of both plant and soil microbial communities. Importantly, our study provides direct evidence that soil microorganisms are not "drivers" of plant community dynamics. We found that soil fungi and bacteria manifest different community assemblies in response to treatments. Soil fungi act as "passengers," that is, soil microorganisms reflect plant community dynamics but do not alter it, whereas soil bacteria are neither "drivers" nor "passengers" of plant community dynamics in early successional ecosystems. These results are critical for understanding the community assembly of plant and soil microbial communities under natural conditions and are directly relevant for ecosystem management and restoration.
- Klíčová slova
- bacteria, coexistence, ecosystem dynamics, ecosystem restoration, field experiment, fungi, plant community, soil microbial community, sterilization, whole‐soil inoculation,
- MeSH
- Bacteria * klasifikace MeSH
- ekosystém * MeSH
- houby * fyziologie MeSH
- půdní mikrobiologie * MeSH
- rostliny * mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
A tenet of ecology is that temporal variability in ecological structure and processes tends to decrease with increasing spatial scales (from locales to regions) and levels of biological organization (from populations to communities). However, patterns in temporal variability across trophic levels and the mechanisms that produce them remain poorly understood. Here we analyzed the abundance time series of spatially structured communities (i.e., metacommunities) spanning basal resources to top predators from 355 freshwater sites across three continents. Specifically, we used a hierarchical partitioning method to disentangle the propagation of temporal variability in abundance across spatial scales and trophic levels. We then used structural equation modeling to determine if the strength and direction of relationships between temporal variability, synchrony, biodiversity, and environmental and spatial settings depended on trophic level and spatial scale. We found that temporal variability in abundance decreased from producers to tertiary consumers but did so mainly at the local scale. Species population synchrony within sites increased with trophic level, whereas synchrony among communities decreased. At the local scale, temporal variability in precipitation and species diversity were associated with population variability (linear partial coefficient, β = 0.23) and population synchrony (β = -0.39) similarly across trophic levels, respectively. At the regional scale, community synchrony was not related to climatic or spatial predictors, but the strength of relationships between metacommunity variability and community synchrony decreased systematically from top predators (β = 0.73) to secondary consumers (β = 0.54), to primary consumers (β = 0.30) to producers (β = 0). Our results suggest that mobile predators may often stabilize metacommunities by buffering variability that originates at the base of food webs. This finding illustrates that the trophic structure of metacommunities, which integrates variation in organismal body size and its correlates, should be considered when investigating ecological stability in natural systems. More broadly, our work advances the notion that temporal stability is an emergent property of ecosystems that may be threatened in complex ways by biodiversity loss and habitat fragmentation.
- Klíčová slova
- Moran effect, community synchrony, compensatory dynamics, international long-term ecological research (ILTER), metacommunities, mobile consumers, portfolio effect, temporal variability,
- MeSH
- biodiverzita MeSH
- časové faktory MeSH
- ekosystém * MeSH
- potravní řetězec * MeSH
- sladká voda MeSH
- Publikační typ
- časopisecké články MeSH
Belowground niche partitioning presents a key mechanism for maintaining species coexistence and diversity. Its importance is currently reinforced by climate change that alters soil hydrological conditions. However, experimental tests examining the magnitude of its change under climate change are scarce. We combined measurements of oxygen stable isotopes to infer plant water-uptake depths and extreme drought manipulation in grasslands. Belowground niche partitioning was evidenced by different water-uptake depths of co-occurring species under ambient and extreme drought conditions despite an increased overlap among species due to a shift to shallower soil layers under drought. A co-occurrence of contrasting strategies related to the change of species water-uptake depth distribution was likely to be key for species to maintain some extent of belowground niche partitioning and could contribute to stabilizing coexistence under drought. Our results suggest that belowground niche partitioning could mitigate negative effects on diversity imposed by extreme drought under future climate.
- Klíčová slova
- belowground niche partitioning, climate change, extreme drought, grasslands, hydrological niche segregation, oxygen stable isotopes, rainout shelter, water-uptake depth,
- MeSH
- klimatické změny MeSH
- období sucha * MeSH
- pastviny MeSH
- půda MeSH
- rostliny * MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- půda MeSH
- voda MeSH
Biodiversity drives ecosystem processes, but its influence on deadwood decomposition is poorly understood. To test the effects of insect diversity on wood decomposition, we conducted a mesocosm experiment manipulating the species richness and functional diversity of beetles. We applied a novel approach using computed tomography scanning to quantify decomposition by insects and recorded fungal and bacterial communities. Decomposition rates increased with both species richness and functional diversity of beetles, but the effects of functional diversity were linked to beetle biomass, and to the presence of one large-bodied species in particular. This suggests that mechanisms behind observed biodiversity effects are the selection effect, which is linked to the occurrence probability of large species, and the complementarity effect, which is driven by functional differentiation among species. Additionally, beetles had significant indirect effects on wood decomposition via bacterial diversity, fungal community composition, and fungal biomass. Our experiment shows that wood decomposition is driven by beetle diversity and its interactions with bacteria and fungi. This highlights that both insect and microbial biodiversity are critical to maintaining ecosystem functioning.
- Klíčová slova
- biodiversity-ecosystem functioning, functional diversity, insect diversity, insect-microbe interactions, wood decomposition,
- MeSH
- Bacteria MeSH
- biodiverzita MeSH
- brouci * MeSH
- dřevo * mikrobiologie MeSH
- ekosystém MeSH
- hmyz MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- extinkce biologická * MeSH
- reprodukovatelnost výsledků MeSH
- zachování přírodních zdrojů * metody MeSH
- Publikační typ
- dopisy MeSH
- komentáře MeSH
