Impacts of climate on the biodiversity-productivity relationship in natural forests

Amphibians rise to flourishing under climate change on the Qinghai-Tibetan Plateau

Amphibian populations are declining globally due to climate change. However, the impacts on the geographic distribution of amphibians on the Qinghai-Tibetan Plateau (QTP), a global biodiversity hotspot with 112 species of amphibians that is sensitive to global climate change, remains unclear. In this study, MaxEnt and barycentre shift analyses were performed to reveal the impact of climate change on the potential future habitats of amphibians on the QTP using the BCC-CSM2-MR global climate model of the Coupled Model Intercomparison Projects Phase 6 (CMIP6) climate pattern with three shared socioeconomic pathways (SSP). In contrast to the widespread decline in the amphibian population, the future scenarios projected an increase in most amphibian habitats on the QTP, accompanied by migration to higher elevations or latitudes under three climatic projections (SSP 1-2.6, 3-7.0, and 5-8.5). Average annual precipitation was the most crucial environmental variable impacting the future distribution of amphibians. The findings indicate that amphibians would flourish under climate change on the QTP, which is of great significance for the protection of amphibians and biodiversity on the QTP.

Leaf isotopes reveal tree diversity effects on the functional responses to the pan-European 2018 summer drought

Recent droughts have strongly impacted forest ecosystems and are projected to increase in frequency, intensity, and duration in the future together with continued warming. While evidence suggests that tree diversity can regulate drought impacts in natural forests, few studies examine whether mixed tree plantations are more resistant to the impacts of severe droughts. Using natural variations in leaf carbon (C) and nitrogen (N) isotopic ratios, that is δ13C and δ15N, as proxies for drought response, we analyzed the effects of tree species richness on the functional responses of tree plantations to the pan-European 2018 summer drought in seven European tree diversity experiments. We found that leaf δ13C decreased with increasing tree species richness, indicating less drought stress. This effect was not related to drought intensity, nor desiccation tolerance of the tree species. Leaf δ15N increased with drought intensity, indicating a shift toward more open N cycling as water availability diminishes. Additionally, drought intensity was observed to alter the influence of tree species richness on leaf δ15N from weakly negative under low drought intensity to weakly positive under high drought intensity. Overall, our findings suggest that dual leaf isotope analysis helps understand the interaction between drought, nutrients, and species richness.

Enhancing ecosystem productivity and stability with increasing canopy structural complexity in global forests

Forest canopy structural complexity (CSC) plays a crucial role in shaping forest ecosystem productivity and stability, but the precise nature of their relationships remains controversial. Here, we mapped the global distribution of forest CSC and revealed the factors influencing its distribution using worldwide light detection and ranging data. We find that forest CSC predominantly demonstrates significant positive relationships with forest ecosystem productivity and stability globally, although substantial variations exist among forest ecoregions. The effects of forest CSC on productivity and stability are the balanced results of biodiversity and resource availability, providing valuable insights for comprehending forest ecosystem functions. Managed forests are found to have lower CSC but more potent enhancing effects of forest CSC on ecosystem productivity and stability than intact forests, highlighting the urgent need to integrate forest CSC into the development of forest management plans for effective climate change mitigation.

Vertical structural complexity of plant communities represents the combined effects of resource acquisition and environmental stress on the Tibetan Plateau

The vertical structural complexity (VSC) of plant communities reflects the occupancy of spatial niches and is closely related to resource utilization and environmental adaptation. However, understanding the large-scale spatial pattern of VSC and its underlying mechanisms remains limited. Here, we systematically investigate 2013 plant communities through grid sampling on the Tibetan Plateau. VSC is quantified as the maximum plant height within a plot (Height-max), coefficient of variation of plant height (Height-var), and Shannon evenness of plant height (Height-even). Precipitation dominates the spatial variation in VSC in forests and shrublands, supporting the classic physiological tolerance hypothesis. In contrast, for alpine meadows, steppes, and desert grasslands in extreme environments, non-resource limiting factors (e.g., wide diurnal temperature ranges and strong winds) dominate VSC variation. Generally, with the shifting of climate from favorable to extreme, the effect of resource availability gradually decreases, but the effect of non-resource limiting factors gradually increases, and that the physiological tolerance hypothesis only applicable in favorable conditions. With the help of machine learning models, maps of VSC at 1-km resolution are produced for the Tibetan Plateau. Our findings and maps of VSC provide insights into macroecological studies, especially for adaptation mechanisms and model optimization.

Strategies for breeding crops for future environments

The green revolution successfully increased agricultural output in the early 1960s by relying primarily on three pillars: plant breeding, irrigation, and chemical fertilization. Today, the need to reduce the use of chemical fertilizers, water scarcity, and future environmental changes, together with a growing population, requires innovative strategies to adapt to a new context and prevent food shortages. Therefore, scientists from around the world are directing their efforts to breed crops for future environments to sustainably produce more nutritious food. Herein, we propose scientific avenues to be reinforced in selecting varieties, including crop wild relatives, either for monoculture or mixed cropping systems, taking advantage of plant-microbial interactions, while considering the diversity of organisms associated with crops and unlocking combinatorial nutritional stresses.

Ecosystem multifunctionality, maximum height, and biodiversity of shrub communities affected by precipitation fluctuations in Northwest China

Introduction

Dryland ecosystems face serious threats from climate change. Establishing the spatial pattern of ecosystem multifunctionality, maximum height and the correlation of biodiversity patterns with climate change is important for understanding changes in complex ecosystem processes. However, the understanding of their relationships across large spatial areas remains limited in drylands.

Methods

Accordingly, this study examined the spatial patterns of ecosystem multifunctionality, maximum height and considered a set of potential environmental drivers by investigating natural shrub communities in Northwest China.

Results

We found that the ecosystem multifunctionality (EMF) and maximum height of shrub communities were both affected by longitude, which was positively correlated with the precipitation gradient. Specifically, the EMF was driven by high precipitation seasonality, and the maximum height was driven by high precipitation stability during the growing season. Among the multiple biodiversity predictors, species beta diversity (SD-beta) is the most common in determining EMF, although this relationship is weak.

Discussion

Unlike tree life form, we did not observe biodiversity-maximum height relationships in shrub communities. Based on these results, we suggest that more attention should be paid to the climatical fluctuations mediated biodiversity mechanisms, which are tightly correlated with ecosystem's service capacity and resistance capacity under a rapid climate change scenario in the future.

Water-limited environments affect the association between functional diversity and forest productivity

The link between biodiversity and ecosystem function can depend on environmental conditions. This contingency can impede our ability to predict how biodiversity-ecosystem function (BEF) relationships will respond to future environmental change, causing a clear need to explore the processes underlying shifts in BEF relationships across large spatial scales and broad environmental gradients. We compiled a dataset on five functional traits (maximum height, wood density, specific leaf area [SLA], seed size, and xylem vulnerability to embolism [P50]), covering 78%-90% of the tree species in the National Forest Inventory from Italy, to test (i) how a water limitation gradient shapes the functional composition and diversity of forests, (ii) how functional composition and diversity of trees relate to forest annual increment via mass ratio and complementarity effects, and (iii) how the relationship between functional diversity and annual increment varies between Mediterranean and temperate climate regions. Functional composition varied with water limitation; tree communities tended to have more conservative traits in sites with higher levels of water limitation. The response of functional diversity differed among traits and climatic regions but among temperate forest plots, we found a consistent increase of functional diversity with water limitation. Tree diversity was positively associated with annual increment of Italian forests through a combination of mass ratio and niche complementarity effects, but the relative importance of these effects depended on the trait and range of climate considered. Specifically, niche complementarity effects were more strongly associated with annual increment in the Mediterranean compared to temperate forests. Synthesis: Overall, our results suggest that biodiversity mediates forest annual increment under water-limited conditions by promoting beneficial interactions between species and complementarity in resource use. Our work highlights the importance of conserving functional diversity for future forest management to maintain forest annual increment under the expected increase in intensity and frequency of drought.

A critical assessment of the biodiversity-productivity relationship in forests and implications for conservation

The question of whether biodiversity conservation and carbon conservation can be synergistic hinges on the form of the biodiversity-productivity relationship (BPR), a fundamental ecological pattern. The stakes are particularly high when it comes to forests, which at a global level comprises a large fraction of both biodiversity and carbon. And yet, in forests, the BPR is relatively poorly understood. In this review, we critically evaluate research on forest BPRs, focussing on the experimental and observational studies of the last 2 decades. We find general support for a positive forest BPR, suggesting that biodiversity and carbon conservation are synergistic to a degree. However, we identify several major caveats: (i) although, on average, productivity may increase with biodiversity, the highest-yielding forests are often monocultures of very productive species; (ii) productivity typically saturates at fewer than ten species; (iii) positive BPRs can be driven by some third variable, in particular stem density, instead of a causal arrow from biodiversity to productivity; (iv) the BPR's sign and magnitude varies across spatial grains and extents, and it may be weak at scales relevant to conservation; and (v) most productivity estimates in forests are associated with large errors. We conclude by explaining the importance of these caveats for both conservation programmes focussed on protection of existing forests and conservation programmes focussed on restoring or replanting forests.

Contribution of tree community structure to forest productivity across a thermal gradient in eastern Asia

Despite their fundamental importance the links between forest productivity, diversity and climate remain contentious. We consider whether variation in productivity across climates reflects adjustment among tree species and individuals, or changes in tree community structure. We analysed data from 60 plots of humid old-growth forests spanning mean annual temperatures (MAT) from 2.0 to 26.6 °C. Comparing forests at equivalent aboveground biomass (160 Mg C ha^-1), tropical forests ≥24 °C MAT averaged more than double the aboveground woody productivity of forests <12 °C (3.7 ± 0.3 versus 1.6 ± 0.1 Mg C ha^-1 yr^-1). Nonetheless, species with similar standing biomass and maximum stature had similar productivity across plots regardless of temperature. We find that differences in the relative contribution of smaller- and larger-biomass species explained 86% of the observed productivity differences. Species-rich tropical forests are more productive than other forests due to the high relative productivity of many short-stature, small-biomass species.

Higher productivity in forests with mixed mycorrhizal strategies

Decades of theory and empirical studies have demonstrated links between biodiversity and ecosystem functioning, yet the putative processes that underlie these patterns remain elusive. This is especially true for forest ecosystems, where the functional traits of plant species are challenging to quantify. We analyzed 74,563 forest inventory plots that span 35 ecoregions in the contiguous USA and found that in ~77% of the ecoregions mixed mycorrhizal plots were more productive than plots where either arbuscular or ectomycorrhizal fungal-associated tree species were dominant. Moreover, the positive effects of mixing mycorrhizal strategies on forest productivity were more pronounced at low than high tree species richness. We conclude that at low richness different mycorrhizal strategies may allow tree species to partition nutrient uptake and thus can increase community productivity, whereas at high richness other dimensions of functional diversity can enhance resource partitioning and community productivity. Our findings highlight the importance of mixed mycorrhizal strategies, in addition to that of taxonomic diversity in general, for maintaining ecosystem functioning in forests.

Integrating gradient with scale in ecological and evolutionary studies

Gradient and scale are two key concepts in ecology and evolution that are closely related but inherently distinct. While scale commonly refers to the dimensional space of a specific ecological/evolutionary (eco-evo) issue, gradient measures the range of a given variable. Gradient and scale can jointly and interactively influence eco-evo patterns. Extensive previous research investigated how changing scales may affect the observation and interpretation of eco-evo patterns; however, relatively little attention has been paid to the role of changing gradients. Here, synthesizing recent research progress, we suggest that the role of scale in the emergence of ecological patterns should be evaluated in conjunction with considering the underlying environmental gradients. This is important because, in most studies, the range of the gradient is often part of its full potential range. The difference between sampled (partial) versus potential (full) environmental gradients may profoundly impact observed eco-evo patterns and alter scale-gradient relationships. Based on observations from both field and experimental studies, we illustrate the underlying features of gradients and how they may affect observed patterns, along with the linkages of these features to scales. Since sampled gradients often do not cover their full potential ranges, we discuss how the breadth and the starting and ending positions of key gradients may affect research design and data interpretation. We then outline potential approaches and related perspectives to better integrate gradient with scale in future studies.

Tropical forest strata shifts in plant structural diversity-aboveground carbon relationships along altitudinal gradients

Aboveground carbon storage in forests can be influenced by both structural and compositional diversity of plant communities. However, the relative and interactive effects of structural and compositional diversity on multilevel aboveground carbon storage across forest strata and how these relationships vary with altitude and soil nutrients remain unclear. Using data obtained from 34 tropical forest plots (total area 8.5 ha) in Hainan Island, China, we analyzed the relationships between aboveground carbon at four levels (litter, understory, overstory, and whole-community) with structural diversity (diameter and height diversity) and compositional diversity (species diversity and evenness) in the understory and overstory. The direct and indirect effects of altitude, soil nutrients (total N and total P and N/P ratio), structural diversity, and compositional diversity on aboveground carbon were explored via Bayesian structural equation modeling. The results showed that structural diversity, rather than compositional diversity, in overstory stratum determined aboveground carbon. Specifically, overstory structural diversity was negatively associated with understory carbon, while positively associated with overstory and whole-community carbon. Furthermore, diversity‑carbon relationships were slightly affected by soil nutrients but strongly by altitude. Specifically, the relationship between overstory and whole-community carbon content with overstory tree height diversity weakened with altitude, while their relationship with overstory diameter diversity strengthened. Altitude directly and indirectly affected overstory tree height and diameter diversity through overstory species diversity, thereby reducing understory and increasing overstory and whole-community carbon. Altitude directly promoted litter carbon. We provide evidence that the effects of plant diversity on aboveground carbon storage are forest strata- and altitude-dependent. As overstory structural diversity plays a crucial role in storing aboveground carbon at all altitudes, we proposed that focusing on overstory structural diversity would be promising for predicting trends in how plant diversity affects aboveground carbon in response to climate change.

Nitrogen enrichment alters climate sensitivity of biodiversity and productivity differentially and reverses the relationship between them in an alpine meadow

Biodiversity and productivity that highly determine ecosystem services are varying largely under global change. However, the climate sensitivity of them and their relationship are not well understood, especially in the context of increasing nitrogen (N) deposition. Here, based on a six-year N manipulation experiment in an alpine meadow, we quantified interannual climate sensitivity of species richness (SR) and above-ground net primary productivity (ANPP) as well as SR-ANPP relationship as affected by six N addition rate (N_rate) gradients. We found that interannual variations in ANPP and SR were mainly driven by temperature instead of precipitation. In the plots without N addition, higher temperature substantially increased ANPP but reduced SR across years, thus resulting in a negative SR-ANPP relationship. However, the negative and positive responses of SR and ANPP to temperature increased and declined significantly with increasing N_rate, respectively, leading to a shift of the negative relationship between SR and ANPP into a positive one under high N_rate. Moreover, the adverse influence of drought on SR and ANPP would be aggravated by N fertilization, as indicated by the increased positive effect of precipitation on them under N enrichment. Our findings indicate that climate sensitivity of productivity and biodiversity may be misestimated if the impact of N deposition is not considered, and the importance of biodiversity to maintain productivity would enhance as N deposition increases. This study provides a new insight to explain variation of biodiversity-productivity relationship along with environmental changes.

Coupling of plant and mycorrhizal fungal diversity: its occurrence, relevance, and possible implications under global change

First principles predict that diversity at one trophic level often begets diversity at other levels, suggesting plant and mycorrhizal fungal diversity should be coupled. Local-scale studies have shown positive coupling between the two, but the association is less consistent when extended to larger spatial and temporal scales. These inconsistencies are likely due to divergent relationships of different mycorrhizal fungal guilds to plant diversity, scale dependency, and a lack of coordinated sampling efforts. Given that mycorrhizal fungi play a central role in plant productivity and nutrient cycling, as well as ecosystem responses to global change, an improved understanding of the coupling between plant and mycorrhizal fungal diversity across scales will reduce uncertainties in predicting the ecosystem consequences of species gains and losses.

Multispecies forest plantations outyield monocultures across a broad range of conditions

Multispecies tree planting has long been applied in forestry and landscape restoration in the hope of providing better timber production and ecosystem services; however, a systematic assessment of its effectiveness is lacking. We compiled a global dataset of matched single-species and multispecies plantations to evaluate the impact of multispecies planting on stand growth. Average tree height, diameter at breast height, and aboveground biomass were 5.4, 6.8, and 25.5% higher, respectively, in multispecies stands compared with single-species stands. These positive effects were mainly the result of interspecific complementarity and were modulated by differences in leaf morphology and leaf life span, stand age, planting density, and temperature. Our results have implications for designing afforestation and reforestation strategies and bridging experimental studies of biodiversity-ecosystem functioning relationships with real-world practices.

Higher tree diversity is linked to higher tree mortality

Examining the relationship between tree diversity and ecosystem functioning has been a recent focus of forest ecology. Particular emphasis has been given to the impact of tree diversity on productivity and to its potential to mitigate negative global change effects; however, little attention has been paid to tree mortality. This is critical because both tree mortality and productivity underpin forest ecosystem dynamics and therefore forest carbon sequestration. Neglecting tree mortality leaves a large part of the picture undocumented. Here we show that increasingly diverse forest stands have increasingly high mortality probabilities. We found that the most species-rich stands in temperate biomes had mortality probabilities more than sevenfold higher than monospecific stands (∼0.6% year−1 in monospecific stands to 4.0% year−1 in the most species-rich stands) while in boreal stands increases were less pronounced but still significant (∼1.1% year−1 in monospecific stands to 1.8% year−1 in the most species-rich stands). Tree species richness was the third-most-important predictor of mortality in our models in temperate forests and the fifth-most-important predictor in boreal forests. Our results highlight that while the promotion of tree diversity undoubtedly has many positive effects on ecosystem functioning and the services that trees provide to humanity, it remains important to consider all aspects of forest dynamics in order to properly predict the implications of maintaining and promoting tree diversity.

Beneficial effects of warming on temperate tree carbon storage depend on precipitation and mycorrhizal types

Despite evidence from multiple observation data sets and numerical model simulations that interactions between biotic and abiotic factors control tree carbon (C) storage in the Northern Hemisphere, it remains unclear whether the effect of one factor will be altered by other factors. Here, we used forest inventory data consisting of more than 500,000 trees from 1910 plots to explore the relative importance of these drivers of plant C storage in northeast China. We found that tree C storage was significantly positively associated with mean annual temperature (MAT). After controlling for the role of mean annual precipitation (MAP), directionality in the tree C storage-MAT relationship reversed, indicating that the direction of MAT affecting tree C storage depends on MAP. Accounting for the effects of tree-fungal symbioses on plant resistance to drought and warming, we found that warming increased AM tree C storage even after controlling the role of MAP, but decreased EcM tree C storage after controlling the role of MAP. Our analysis also shows that species richness, especially the relative richness of AM tree species, had a significantly positive relationship with all types of tree C storage. Our findings have implications for improving temperate forest C sink and afforestation strategies: the increasing richness of AM trees has the potential to enhance the tree C sink and reduce the sensitivity of warming-induced tree growth benefits to changes in precipitation.

Species pool size and rainfall account for the relationship between biodiversity and biomass production in natural forests of China

The strength of biodiversity-biomass production relationships increases with increasing environmental stress and time. However, we know little about the effects of abiotic (e.g., climate) and biotic (e.g., species pool and community composition) factors on this trend. Whether variation in biomass production is best explained by phylogenetic diversity metrics or traditional measures of species richness also remains elusive. We compiled estimates of community composition and biomass production for tree species in 111 permanent quadrats spanning three natural forests (tropical, subtropical, and temperate) in China. Based on ~10 years of data, we compared temperature, rainfall, species pool size, and community composition in each forest each year. We estimated species richness and phylogenetic diversity in each quadrat each year; the latter metric was based on the sum of branch lengths of a phylogeny that connects species in each quadrat each year. Using generalized linear mixed-effect models, we found that top-ranked models included the interaction between forest and biodiversity and the interaction between forest and year for both biodiversity metrics. Variation in biomass production was best explained by phylogenetic diversity; biomass production generally increased with phylogenetic diversity, and the relationship was stronger in subtropical and temperate forests. Increasing species pool size, temperature, and rainfall and decreasing inter-quadrat dissimilarity range shifted the relationship between biomass production and phylogenetic diversity from positive to neutral. When considered alone, species pool size had the strongest influence on biomass production, while species pool size, rainfall, and their interaction with phylogenetic diversity constituted the top-ranked model. Our study highlights the importance of species pool size and rainfall on the relationship between phylogenetic diversity and biomass production in natural forest ecosystems.

Climatic conditions, not above- and belowground resource availability and uptake capacity, mediate tree diversity effects on productivity and stability

Tree species diversity promotes multiple ecosystem functions and services. However, little is known about how above- and belowground resource availability (light, nutrients, and water) and resource uptake capacity mediate tree species diversity effects on aboveground wood productivity and temporal stability of productivity in European forests and whether the effects differ between humid and arid regions. We used the data from six major European forest types along a latitudinal gradient to address those two questions. We found that neither leaf area index (a proxy for light uptake capacity), nor fine root biomass (a proxy for soil nutrient and water uptake capacity) was related to tree species richness. Leaf area index did, however, enhance productivity, but negatively affected stability. Productivity was further promoted by soil nutrient availability, while stability was enhanced by fine root biomass. We only found a positive effect of tree species richness on productivity in arid regions and a positive effect on stability in humid regions. This indicates a possible disconnection between productivity and stability regarding tree species richness effects. In other words, the mechanisms that drive the positive effects of tree species richness on productivity do not per se benefit stability simultaneously. Our findings therefore suggest that tree species richness effects are largely mediated by differences in climatic conditions rather than by differences in above- and belowground resource availability and uptake capacity at the regional scales.

Biodiversity promotes ecosystem functioning despite environmental change

Three decades of research have demonstrated that biodiversity can promote the functioning of ecosystems. Yet, it is unclear whether the positive effects of biodiversity on ecosystem functioning will persist under various types of global environmental change drivers. We conducted a meta‐analysis of 46 factorial experiments manipulating both species richness and the environment to test how global change drivers (i.e. warming, drought, nutrient addition or CO₂ enrichment) modulated the effect of biodiversity on multiple ecosystem functions across three taxonomic groups (microbes, phytoplankton and plants). We found that biodiversity increased ecosystem functioning in both ambient and manipulated environments, but often not to the same degree. In particular, biodiversity effects on ecosystem functioning were larger in stressful environments induced by global change drivers, indicating that high‐diversity communities were more resistant to environmental change. Using a subset of studies, we also found that the positive effects of biodiversity were mainly driven by interspecific complementarity and that these effects increased over time in both ambient and manipulated environments. Our findings support biodiversity conservation as a key strategy for sustainable ecosystem management in the face of global environmental change.

Effects of the interaction among climate, terrain and human activities on biodiversity on the Qinghai-Tibet Plateau

Disentangling the driving factors of biodiversity is critical for understanding biogeographical patterns of vegetation and ecosystem function. However, the biotic and abiotic attributes that shape biodiversity on the Qinghai-Tibet Plateau (QTP) are still not been quantified. Previous studies have not distinguished the direct and indirect effects of climate, terrain, and human disturbance on biodiversity. In this study, we applied a structural equation model (SEM) to assess the interactions among 4 attributes and biodiversity. A conceptual framework with 8 explanatory variables was built to identify the driving forces of biodiversity. A geographically weighted regression (GWR) model was applied to explore the response sensitivity of biodiversity to climate, terrain, and human attributes. We found that the SEM passed the tests of validity, reliability and fit, indicating that the hypothetical model was reasonable and credible. Among terrain conditions, elevation had the greatest, most-negative effect on biodiversity. Among the human factors, distance to town showed the strongest and most negative influence on biodiversity. Among the climate factors, precipitation had the greatest influence on biodiversity. Moreover, the direct effects of terrain and human activity were 0.348 and 0.135, respectively, and their indirect effects were 0.769 and 0.213, respectively, revealing that they had stronger indirect effects on biodiversity than direct effects. Climate exhibited only direct effects on biodiversity and had no indirect effects. The total effects of climate, terrain and human activity on biodiversity were 1.39, 0.35 and 0.13, respectively, indicating that climate was the main driving force of biodiversity on the QTP. The response sensitivity of biodiversity to climate, terrain and human factors showed obvious spatial variations. This study contributes to exploring the interactive effects and driving mechanisms of human-natural attributes on biodiversity and provides further effective guidance and support for biodiversity conservation and restoration.

Similar tree species richness-productivity response but differing effects on carbon stocks and timber production in eastern US and continental Spain

Unimodal response of tree species richness to increases in aboveground productivity is evident in grasslands but to a lesser extent in forests, where confounding factors (e.g., abiotic factors and management regimes) may alter the response and compromise the delivery of ecosystem services. We hypothesize that unimodal response of biomass accumulation through increased species richness leads to greater tree above ground carbon (AGC) stocks and thus climate regulation but not necessarily higher timber volume production for human consumption across portions of North American and European forests. We first evaluated the biodiversity-productivity pattern and assessed if the addition of potential confounding variables altered the response. Afterwards, we integrated direct and indirect effects of species richness and confounding factors in the modelling of aboveground carbon stock and timber volume. We confirm an increase in carbon stocks concomitant with an increase in tree species richness up to an optimum biomass value in both regions. Tree species richness had a marginal effect on both aboveground carbon stocks and timber volume with a trade-off in the eastern US. Biomass accumulation is lower in tree plantations than in natural forests, although volume increased with species richness. Naturally-regenerated forests needed as much as double the number of tree species than plantations to reach the same carbon stocks. Distinct ecosystem services (AGC and timber volume) showed unique pathways of achieving their maximum provisioning. As increasing forest resilience to global change requires a fundamental understanding of how tree species combine with changing climatic conditions to drive the provisioning of various ecosystem services, further examination of this study's findings across additional biogeographical regions may lead the way to unraveling such dynamics and empowering adaptive management.

The impact of global climate change on the number and replacement of provisioning ecosystem services of Brazilian Cerrado plants

It is essential to predict areas of losses or exchanges of ecosystem services to adapt communities to the impacts caused by climate change. Particularly for provisioning ecosystem services provided by economically important plant species, understanding the association between climate change impacts and deforestation of native vegetation increases the accuracy of those predictions. Thus, we aim to (i) map the richness of provisioning ecosystem services from economically important native plants; (ii) use forecasts (present and future) of the distribution of ecosystem services to assess areas of changes in the number and type of provisioning ecosystems services. We evaluated provisioning ecosystem services from 110 Cerrado native species of economic importance for the local population. We determined the potential distribution of these plants using ecological niche modeling techniques, which were grouped according to the 21 different services provided. The forecasts for variation in richness and type of service used four future climate change scenarios (RCPs 4.5 and 8.5 in 2050 and 2070). The service losses detected in our models were associated with variables representing the progress of native vegetation deforestation in the biome due to agricultural expansion. Currently, ecosystem services can be found simultaneously in practically the entire biome. However, changes in the global climate will impact the potential geographic distribution of those plants, causing many areas in the biome to have reduced availability of potential ecosystem services. Moreover, due to the association between exposure to climate change and deforestation of native vegetation, the northern region of the biome will likely have the distribution of ecosystem services severely affected.

Estimation of Current and Future Suitable Areas for Tapirus pinchaque in Ecuador

At present, climate change is a direct threat to biodiversity and its effects are evidenced by an increasingly accelerated loss of biodiversity. This study identified the main threats presently facing the Tapirus pinchaque species in Ecuador, generated predictive models regarding its distribution, and analyzed the protected areas as a conservation tool. The methodology was based on a literature review and the application of binary predictive models to achieve these objectives. The main results indicate that the T. pinchaque is seriously threatened, mainly by changes in land use. In addition, three models were selected that show current and future suitable areas for the conservation of the species. Its current distribution amounts to 67,805 km2, 33% (22,872 km2) of which is located in 31 of the 61 protected areas. Finally, it is important to take timely actions focused on biodiversity conservation, considering the importance of balance in ecosystems to the humans dependent thereof, and the results regarding the changes in the current and future distribution areas of the mountain tapir are a great contribution to be used as a management tool for its conservation.

The Biodiversity–Biomass Relationship of Aquatic Macrophytes Is Regulated by Water Depth: A Case Study of a Shallow Mesotrophic Lake in China

The relationship between biodiversity and productivity (or biomass production) (BPR) has been a popular topic in macroecology and debated for decades. However, this relationship is poorly understood in macrophyte communities, and the mechanism of the BPR pattern of the aquatic macrophyte community is not clear. We investigated 78 aquatic macrophyte communities in a shallow mesotrophic freshwater lake in the middle and lower reaches of the Yangtze River in China. We analyzed the relationship between biodiversity (species richness, diversity, and evenness indices) and community biomass, and the effects of water environments and interspecific interactions on biodiversity–biomass patterns. Unimodal patterns between community biomass and diversity indices instead of evenness indices are shown, and these indicate the importance of both the number and abundance of species when studying biodiversity–biomass patterns under mesotrophic conditions. These patterns were moderated by species identity biologically and water depth environmentally. However, water depth determined the distribution and growth of species with different life-forms as well as species identities through environmental filtering. These results demonstrate that water depth regulates the biodiversity–biomass pattern of the aquatic macrophyte community as a result of its effect on species identity and species distribution. Our study may provide useful information for conservation and restoration of macrophyte vegetation in shallow lakes through matching water depth and species or life-form combinations properly to reach high ecosystem functions and services.

Climate regulates the functional traits - aboveground biomass relationships at a community-level in forests: A global meta-analysis

The relationships between plant functional traits and aboveground biomass (AGB) stock have been explored across forest biomes. Yet, meta-analyses synthesizing our understanding regarding the influences of climate and soil on the functional traits - AGB relationships at a community-level in global forests are still unavailable. Here, we evaluated the latitudinal gradient in the functional traits -AGB relationships in forests, including functional trait diversity (FTD) - AGB (FTD-AGB), community-weighted mean (CWM) of conservative traits (CWMCT-AGB), CWM of acquisitive traits (CWMAT-AGB), and CWM of plant maximum height or diameter (FunDom-AGB), and then answer the question whether climate and soil conditions modulate the functional traits - AGB relationships in global forests. To do so, we selected those studies which reported the relationships of FTD and CWM with AGB stock (i.e. in Mg ha^-1) rather with AGB productivity or growth (i.e. Mg ha^-1 yr^-1) at a community-level (i.e. forest plot). By using piecewise structural equation meta-modeling, we found that: (1) functional traits - AGB relationships at a community-level were driven by mean annual temperature (MAT), aridity and soil fertility. (2) Higher MAT and low aridity promoted FTD-AGB relationships but the opposite trend was true for CWMCT-AGB, whereas higher MAT promoted CWMAT-AGB and FunDom-AGB at high aridity levels. (3) The FunDom-AGB relationship increased with increasing the number of forest plots but other relationships declined. (4) The negligible or negative FTD-AGB relationships but the positive AGB-FunDom relationships were conspicuous across global forests, indicating the mass ratio effect in terms of functional dominance. Our meta-analysis suggests that functional dominance and conservative species' strategy in relation to favorable abiotic conditions should be promoted to increase AGB stock under global environmental changes.

Climatic humidity mediates the strength of the species richness-biomass relationship on the Mongolian Plateau steppe

The relationships between biodiversity and ecosystem functioning (BEF) have been extensively studied over past decades. However, the environmental factors affecting their relationships, and how their relationships vary under the influence of environmental factors, remain controversial. Studying the BEF relationships in natural/wild environments is of great significance for devising strategies in biodiversity conservation and ecosystem functioning. Using the data from 75 sites on the Mongolian Plateau steppe, we analyzed the relationship between species richness and biomass with general linear models (GLMs) and linear mixed models (LMMs), and analyzed the variation in the species richness-biomass relationships under environmental conditions by the partial least square path modeling (PLSPM). The results showed that de Martonne aridity index affected both species richness and community biomass in parallel, and that hydrothermal coupling conditions were more important direct impact factors for aboveground biomass. However, the significant species richness-biomass relationships became weaker when the effects of environmental factors (i.e. climate and soil properties) were present. Climate humidity was the most important factor in mediating the relationship between species richness and community biomass. Our research suggested that species richness-biomass relationships are weak in the natural grasslands of the Mongolian Plateau, and that this may be due to the differences in the regional-scale environment and changes in species interactions. We recommend that a more comprehensive understanding of the relationship between diversity and biomass requires further research within broader environmental gradients.

Topography Affects Tree Species Distribution and Biomass Variation in a Warm Temperate, Secondary Forest

A thorough understanding of carbon storage patterns in forest ecosystems is crucial for forest management to slow the rate of climate change. Here, we explored fine-scale biomass spatial patterns in a secondary warm temperate deciduous broad-leaved forest in north China. A 20-ha plot was established and classified by topographic features into ridge, valley, gentle slope, and steep slope habitats. Total tree biomass varied from 103.8 Mg/ha on the gentle slope habitats to 117.4 Mg/ha on the ridge habitats, with an average biomass of 109.6 Mg/ha across the entire plot. A few species produced the majority of the biomass, with five species contributing 78.4% of the total tree biomass. These five species included Quercus mongolica Fisch. ex Ledeb (41.7 Mg/ha, 38.1%), Betula dahurica Pall. (19.8 Mg/ha, 18.0%), Acer mono Maxim. (12.6 Mg/ha, 11.5%), Betula platyphylla Suk. (7.0 Mg/ha, 6.4%), and Populus davidiana Dode. (4.8 Mg/ha, 4.4%). The five species were also associated with certain habitats; for example, Q. mongolica was positively associated with the ridge habitat and A. mono was positively associated with the valley habitat. Results from this work document the variability in forest biomass across a warm temperate forest ecosystem of north China, with implications for managing and accounting forest carbon.