Low multifunctional redundancy of soil fungal diversity at multiple scales

Theory suggests that biodiversity might help sustain multiple ecosystem functions. To evaluate possible biodiversity–multifunctionality relationships in a natural setting, we considered different spatial scales of diversity metrics for soil fungi in the northern forests of Japan. We found that multifunctionality increased with increasing local species richness, suggesting a limited degree of multifunctional redundancy. This diversity–multifunctionality relationship was independent of the compositional uniqueness of each community. However, we still found the importance of community composition, because there was a positive correlation between community dissimilarity and multifunctional dissimilarity across the landscape. This result suggests that functional redundancy can further decrease when spatial variations in identities of both species and functions are simultaneously considered at larger spatial scales. We speculate that different scales of diversity could provide multiple levels of insurance against the loss of functioning if high‐levels of local species diversity and compositional variation across locations are both maintained. Alternatively, making species assemblages depauperate may result in the loss of multifunctionality.     

Land use intensification alters ecosystem multifunctionality via loss of biodiversity and changes to functional composition

Global change, especially land‐use intensification, affects human well‐being by impacting the delivery of multiple ecosystem services (multifunctionality). However, whether biodiversity loss is a major component of global change effects on multifunctionality in real‐world ecosystems, as in experimental ones, remains unclear. Therefore, we assessed biodiversity, functional composition and 14 ecosystem services on 150 agricultural grasslands differing in land‐use intensity. We also introduce five multifunctionality measures in which ecosystem services were weighted according to realistic land‐use objectives. We found that indirect land‐use effects, i.e. those mediated by biodiversity loss and by changes to functional composition, were as strong as direct effects on average. Their strength varied with land‐use objectives and regional context. Biodiversity loss explained indirect effects in a region of intermediate productivity and was most damaging when land‐use objectives favoured supporting and cultural services. In contrast, functional composition shifts, towards fast‐growing plant species, strongly increased provisioning services in more inherently unproductive grasslands.     

Heterogeneous microcommunities and ecosystem multifunctionality in seminatural grasslands under three management modes

Increasing attention has been paid to the relationship between biodiversity and ecosystem functioning (BEF) because of the rapid increase in species loss. However, over the past 20 years, most BEF studies only focused on the effect of species diversity on one or a few ecosystem functions, and only a few studies focused on ecosystem multifunctionality (i.e., the simultaneous provision of several ecosystem functions). Grassland ecosystems have important economic, environmental, and esthetic value; thus, this study focused on the heterogeneous microcommunities in grasslands under three management modes. The multifunctionality index (M‐index) was assessed at community and microcommunity scales, and the relationship between species diversity and multifunctionality was investigated. The communities were found to be respectively composed of one, three, and six microcommunities in grazing, clipping, and enclosure management, based on a two‐way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA) for community structure. Biodiversity and soil indicators showed an apparent degradation of the grazing community, which had the worst M‐index. Clipping and enclosure communities showed no significant difference in biodiversity indices, soil variables, and M‐index; however, these indices were clearly different among microcommunities. Therefore, the microcommunity scale may be suitable to investigate the relationship between vegetation and multifunctionality in seminatural grassland ecosystems. Dominant species richness had more explanatory power for ecosystem multifunctionality than subdominant species richness, rare species richness, and the number of all species. Therefore, it is important to distinguish the role and rank of different species in the species richness–multifunctionality model; otherwise, the model might include redundant and unclear information. Communities with more codominant species whose distribution is also even might have better multifunctionality.     

Testing the effects of plant species loss on multiple ecosystem functions based on extinction scenarios

Ecosystem functions are threatened by continuing global loss of biodiversity. We simultaneously investigated three ecosystem functions and forage nutrient values following potential species extinction scenarios (dominant species removal, rare species removal, end-member species removal and random species removal) in a Mongolian grassland. ANPP, forage nutrient values, litter decomposition, and soil respiration were measured one and/or two years after plant removal. DNA samples of microorganisms extracted from the soil were subjected to metagenomics analysis. Finally, we calculated the multifunctionality, and examined the relationship of multifunctionality with plant and microorganism diversity. Among ecosystem functions, ANPP and litter decomposition rate decreased under random and rare species extinction scenarios, respectively, and forage quality increased when only dominant species had been removed. Diversity and species composition of soil microorganism were not affected by plant species richness or removal scenario. Only genus-level diversity of bacteria and ANPP were significantly and positively correlated with microbial diversity. Taken together, decreasing species richness of plants and soil organisms rarely impaired multifunctionality. Ecosystem functions were relatively robust to realistic disturbances and species extinction in natural grasslands. However, as each function responded differently to the different sets of species removed, the consequences of a realistic non-random extinction scenario for multiple ecosystem functions should be critical to the management of biodiversity loss caused by different disturbances.     

Response diversity determines the resilience of ecosystems to environmental change

A growing body of evidence highlights the importance of biodiversity for ecosystem stability and the maintenance of optimal ecosystem functionality. Conservation measures are thus essential to safeguard the ecosystem services that biodiversity provides and human society needs. Current anthropogenic threats may lead to detrimental (and perhaps irreversible) ecosystem degradation, providing strong motivation to evaluate the response of ecological communities to various anthropogenic pressures. In particular, ecosystem functions that sustain key ecosystem services should be identified and prioritized for conservation action. Traditional diversity measures (e.g. ‘species richness’) may not adequately capture the aspects of biodiversity most relevant to ecosystem stability and functionality, but several new concepts may be more appropriate. These include ‘response diversity’, describing the variation of responses to environmental change among species of a particular community. Response diversity may also be a key determinant of ecosystem resilience in the face of anthropogenic pressures and environmental uncertainty. However, current understanding of response diversity is poor, and we see an urgent need to disentangle the conceptual strands that pervade studies of the relationship between biodiversity and ecosystem functioning. Our review clarifies the links between response diversity and the maintenance of ecosystem functionality by focusing on the insurance hypothesis of biodiversity and the concept of functional redundancy. We provide a conceptual model to describe how loss of response diversity may cause ecosystem degradation through decreased ecosystem resilience. We explicitly explain how response diversity contributes to functional compensation and to spatio‐temporal complementarity among species, leading to long‐term maintenance of ecosystem multifunctionality. Recent quantitative studies suggest that traditional diversity measures may often be uncoupled from measures (such as response diversity) that may be more effective proxies for ecosystem stability and resilience. Certain conclusions and recommendations of earlier studies using these traditional measures as indicators of ecosystem resilience thus may be suspect. We believe that functional ecology perspectives incorporating the effects and responses of diversity are essential for development of management strategies to safeguard (and restore) optimal ecosystem functionality (especially multifunctionality). Our review highlights these issues and we envision our work generating debate around the relationship between biodiversity and ecosystem functionality, and leading to improved conservation priorities and biodiversity management practices that maximize ecosystem resilience in the face of uncertain environmental change.     

Testing the effects of diversity on ecosystem multifunctionality using a multivariate model

Most ecosystems provide multiple services, thus the impact of biodiversity losses on ecosystem functions may be considerably underestimated by studies that only address single functions. We propose a multivariate modelling framework for quantifying the relationship between biodiversity and multiple ecosystem functions (multifunctionality). Our framework consolidates the strengths of previous approaches to analysing ecosystem multifunctionality and contributes several advances. It simultaneously assesses the drivers of multifunctionality, such as species relative abundances, richness, evenness and other manipulated treatments. It also tests the relative importance of these drivers across functions, incorporates correlations among functions and identifies conditions where all functions perform well and where trade‐offs occur among functions. We illustrate our framework using data from three ecosystem functions (sown biomass, weed suppression and nitrogen yield) in a four‐species grassland experiment. We found high variability in performance across the functions in monocultures, but as community diversity increased, performance increased and variability across functions decreased.     

Loss of Rare Fish Species from Tropical Floodplain Food Webs Affects Community Structure and Ecosystem Multifunctionality in a Mesocosm Experiment

Experiments with realistic scenarios of species loss from multitrophic ecosystems may improve insight into how biodiversity affects ecosystem functioning. Using 1000 L mesocoms, we examined effects of nonrandom species loss on community structure and ecosystem functioning of experimental food webs based on multitrophic tropical floodplain lagoon ecosystems. Realistic biodiversity scenarios were developed based on long-term field surveys, and experimental assemblages replicated sequential loss of rare species which occurred across all trophic levels of these complex food webs. Response variables represented multiple components of ecosystem functioning, including nutrient cycling, primary and secondary production, organic matter accumulation and whole ecosystem metabolism. Species richness significantly affected ecosystem function, even after statistically controlling for potentially confounding factors such as total biomass and direct trophic interactions. Overall, loss of rare species was generally associated with lower nutrient concentrations, phytoplankton and zooplankton densities, and whole ecosystem metabolism when compared with more diverse assemblages. This pattern was also observed for overall ecosystem multifunctionality, a combined metric representing the ability of an ecosystem to simultaneously maintain multiple functions. One key exception was attributed to time-dependent effects of intraguild predation, which initially increased values for most ecosystem response variables, but resulted in decreases over time likely due to reduced nutrient remineralization by surviving predators. At the same time, loss of species did not result in strong trophic cascades, possibly a result of compensation and complexity of these multitrophic ecosystems along with a dominance of bottom-up effects. Our results indicate that although rare species may comprise minor components of communities, their loss can have profound ecosystem consequences across multiple trophic levels due to a combination of direct and indirect effects in diverse multitrophic ecosystems.     

Functional structure of biological communities predicts ecosystem multifunctionality

The accelerating rate of change in biodiversity patterns, mediated by ever increasing human pressures and global warming, demands a better understanding of the relationship between the structure of biological communities and ecosystem functioning (BEF). Recent investigations suggest that the functional structure of communities, i.e. the composition and diversity of functional traits, is the main driver of ecological processes. However, the predictive power of BEF research is still low, the integration of all components of functional community structure as predictors is still lacking, and the multifunctionality of ecosystems (i.e. rates of multiple processes) must be considered. Here, using a multiple-processes framework from grassland biodiversity experiments, we show that functional identity of species and functional divergence among species, rather than species diversity per se, together promote the level of ecosystem multifunctionality with a predictive power of 80%. Our results suggest that primary productivity and decomposition rates, two key ecosystem processes upon which the global carbon cycle depends, are primarily sustained by specialist species, i.e. those that hold specialized combinations of traits and perform particular functions. Contrary to studies focusing on single ecosystem functions and considering species richness as the sole measure of biodiversity, we found a linear and non-saturating effect of the functional structure of communities on ecosystem multifunctionality. Thus, sustaining multiple ecological processes would require focusing on trait dominance and on the degree of community specialization, even in species-rich assemblages.     

Higher biodiversity is required to sustain multiple ecosystem processes across temperature regimes

Biodiversity loss is occurring rapidly worldwide, yet it is uncertain whether few or many species are required to sustain ecosystem functioning in the face of environmental change. The importance of biodiversity might be enhanced when multiple ecosystem processes (termed multifunctionality) and environmental contexts are considered, yet no studies have quantified this explicitly to date. We measured five key processes and their combined multifunctionality at three temperatures (5, 10 and 15 °C) in freshwater aquaria containing different animal assemblages (1–4 benthic macroinvertebrate species). For single processes, biodiversity effects were weak and were best predicted by additive‐based models, i.e. polyculture performances represented the sum of their monoculture parts. There were, however, significant effects of biodiversity on multifunctionality at the low and the high (but not the intermediate) temperature. Variation in the contribution of species to processes across temperatures meant that greater biodiversity was required to sustain multifunctionality across different temperatures than was the case for single processes. This suggests that previous studies might have underestimated the importance of biodiversity in sustaining ecosystem functioning in a changing environment.     

Effect of dung beetle species richness and chemical perturbation on multiple ecosystem functions

1. The relationship between biodiversity and ecosystem functioning is typically positive but saturating, suggesting widespread functional redundancy within ecological communities. However, theory predicts that apparent redundancy can be reduced or removed when systems are perturbed, or when multifunctionality (the simultaneous delivery of multiple functions) is considered. 2. Manipulative experiments were used to test whether higher levels of dung beetle species richness enhanced individual functions and multifunctionality, and whether these relationships were influenced by perturbation (in this case, non‐target exposure to the veterinary anthelmintic ivermectin). The four ecosystem functions tested were dung removal, primary productivity, soil faunal feeding activity and reduction in soil bulk density. 3. For individual functions, perturbation had limited effects on functioning, with only dung removal significantly (negatively) affected. Species richness did not, on its own, explain significant variation in the delivery of individual functions. In the case of primary productivity, an interaction between richness and perturbation was found: species‐rich dung beetle assemblages enhanced forage growth in the unperturbed treatment, relative to the perturbed treatment. 4. Using a composite ‘multifunctionality index’ it was found that species‐rich dung beetle assemblages delivered marginally higher levels of multifunctionality in unperturbed conditions; however, this benefit was lost under perturbation. Using a relatively new and robust method of assessing diversity–multifunctionality relationships across a range of thresholds, no significant effect of species richness on multifunctionality was found.     

Litter and soil biodiversity jointly drive ecosystem functions

The decomposition of litter and the supply of nutrients into and from the soil are two fundamental processes through which the above- and belowground world interact. Microbial biodiversity, and especially that of decomposers, plays a key role in these processes by helping litter decomposition. Yet the relative contribution of litter diversity and soil biodiversity in supporting multiple ecosystem services remains virtually unknown. Here we conducted a mesocosm experiment where leaf litter and soil biodiversity were manipulated to investigate their influence on plant productivity, litter decomposition, soil respiration, and enzymatic activity in the littersphere. We showed that both leaf litter diversity and soil microbial diversity (richness and community composition) independently contributed to explain multiple ecosystem functions. Fungal saprobes community composition was especially important for supporting ecosystem multifunctionality (EMF), plant production, litter decomposition, and activity of soil phosphatase when compared with bacteria or other fungal functional groups and litter species richness. Moreover, leaf litter diversity and soil microbial diversity exerted previously undescribed and significantly interactive effects on EMF and multiple individual ecosystem functions, such as litter decomposition and plant production. Together, our work provides experimental evidence supporting the independent and interactive roles of litter and belowground soil biodiversity to maintain ecosystem functions and multiple services.     

Continental mapping of forest ecosystem functions reveals a high but unrealised potential for forest multifunctionality

Humans require multiple services from ecosystems, but it is largely unknown whether trade‐offs between ecosystem functions prevent the realisation of high ecosystem multifunctionality across spatial scales. Here, we combined a comprehensive dataset (28 ecosystem functions measured on 209 forest plots) with a forest inventory dataset (105,316 plots) to extrapolate and map relationships between various ecosystem multifunctionality measures across Europe. These multifunctionality measures reflected different management objectives, related to timber production, climate regulation and biodiversity conservation/recreation. We found that trade‐offs among them were rare across Europe, at both local and continental scales. This suggests a high potential for ‘win‐win’ forest management strategies, where overall multifunctionality is maximised. However, across sites, multifunctionality was on average 45.8‐49.8% below maximum levels and not necessarily highest in protected areas. Therefore, using one of the most comprehensive assessments so far, our study suggests a high but largely unrealised potential for management to promote multifunctional forests.     

Biological soil crusts (biocrusts) as a model system in community,landscape and ecosystem ecology

Model systems have had a profound influence on the development of ecological theory and general principles. Compared to alternatives, the most effective models share some combination of the following characteristics: simpler, smaller, faster, general, idiosyncratic or manipulable. We argue that biological soil crusts (biocrusts) have unique combinations of these features that should be more widely exploited in community, landscape and ecosystem ecology. In community ecology, biocrusts are elucidating the importance of biodiversity and spatial pattern for maintaining ecosystem multifunctionality due to their manipulability in experiments. Due to idiosyncrasies in their modes of facilitation and competition, biocrusts have led to new models on the interplay between environmental stress and biotic interactions and on the maintenance of biodiversity by competitive processes. Biocrusts are perhaps one of the best examples of micro-landscapes—real landscapes that are small in size. Although they exhibit varying patch heterogeneity, aggregation, connectivity and fragmentation, like macro-landscapes, they are also compatible with well-replicated experiments (unlike macro-landscapes). In ecosystem ecology, a number of studies are imposing small-scale, low cost manipulations of global change or state factors in biocrust micro-landscapes. The versatility of biocrusts to inform such disparate lines of inquiry suggests that they are an especially useful model system that can enable researchers to see ecological principles more clearly and quickly.     

Plant functional group identity differentially affects leaf and root decomposition

Losses of species and changes in the composition of plant communities are likely to influence numerous ecosystem functions. Changes in the plant‐soil interactions that control decomposition, in particular, could alter carbon and nutrient cycling in soils and further alter other ecosystem functions. The effects of plant communities on decomposition may depend both on the type of tissue being decomposed and also on the different stages of the decomposition process. We used an experimental design where single plant functional groups were removed from a northern grassland to examine the role of plant identity in determining both short‐term and long‐term above‐ and belowground decomposition rates. Plant removals were conducted across fertilization and fungicide treatments to examine environmental context‐dependency of functional group identity effects on decomposition. There were significant effects of plant functional group identity on aboveground decomposition, with the loss of grasses and forbs slowing decomposition, whereas the effects on belowground decomposition were rare and transient. Effects of plant identity on decomposition were consistent in both short‐ and long‐term decomposition studies indicating that the influences of identity on the decomposition environment remained consistent throughout the different stages of the decomposition process. Both fertilizer and fungicide treatments affected overall decomposition rate, but there were few interactions between these treatments and plant removals. Although current species loss is likely to be happening in concert with environmental changes, the role a species plays in determining ecosystem functions such as decomposition may not be context‐dependent in these northern environments, and this may provide greater predictive power in determining the effects of species loss with changing environments. Further, as plant identity shows significant effects on litter decomposition rates, the effects of current and predicted future biodiversity losses may depend specifically on which species are lost.     

Biodiversity and ecosystem functioning decoupled: invariant ecosystem functioning despite non‐random reductions in consumer diversity

Most research that demonstrates enhancement and stabilization of ecosystem functioning due to biodiversity is based on biodiversity manipulations within one trophic level and measuring changes in ecosystem functions provided by that same trophic level. However, it is less understood whether and how modifications of biodiversity at one trophic level propagate vertically to affect those functions supplied by connected trophic levels or by the whole ecosystem. Moreover, most experimental designs in biodiversity–ecosystem functioning research assume random species loss, which may be of little relevance to non‐randomly assembled communities. Here, we used data from a published ecotoxicological experiment in which an insecticide gradient was applied as an environmental filter to shape consumer biodiversity. We tested how non‐random consumer diversity loss affected gross primary production (an ecosystem function provided by producers) and respiration (an ecosystem function provided by the ecosystem as whole) in species‐rich multitrophic freshwater communities (total of 128 macroinvertebrate and 59 zooplankton species across treatments). The insecticide decreased and destabilized macroinvertebrate and, to a lesser extent, zooplankton diversity. However, these effects on biodiversity neither affected nor destabilized any of the two studied ecosystem functions. The main reason for this result was that species susceptible to environmental filtering were different from those most strongly contributing to ecosystem functioning. The insecticide negatively affected the most abundant species, whereas much less abundant species had the strongest effects on ecosystem functioning. The latter finding may be explained by differences in body size and feeding guild membership. Our results indicate that biodiversity modifications within one trophic level induced by non‐random species loss do not necessarily translate into changes in ecosystem functioning supported by other trophic levels or by the whole community in the case of limited overlap between sensitivity and functionality.     

生物结皮对古尔班通古特沙漠3种荒漠草本植物生长特性与元素吸收的影响

生物结皮有可能通过物理、水文、养分循环影响与之相邻的维管植物,但二者相互关系尚存在着争议。本文以新疆古尔班通古特沙漠广泛分布的地衣结皮为研究对象,分析了生物结皮对3种荒漠草本植物：尖喙牻牛儿苗（Erodium oxyrrhynchum）、条叶庭芥（Alyssum linifolium）和琉苞菊（Hyalea pulchella）的生长及其对元素吸收的影响。研究结果表明：（1）生物结皮对3种荒漠草本植物生长的影响在生长期不同阶段存在差异。在前期,生物结皮的存在促进了植物生物量的累积;而后期,生物结皮却抑制了植物生长。生物结皮的存在显著影响了荒漠草本植物生物量的累积和冠根比。（2）生物结皮的存在显著增加了3种荒漠草本植物对N和K的吸收,而对P的吸收没有显著影响。生物结皮对3种植物Cu、Ca、Mg、Na、Cl的吸收存在种间差异。本研究结果将为该荒漠生态系统潜在的植被演替方向提供重要的科学根据。     

Diversity and Patch-Size Distributions of Biological Soil Crusts Regulate Dryland Ecosystem Multifunctionality

Recent studies report that multifunctionality—the simultaneous provision of multiple ecosystem functions—in drylands depends on biodiversity. Others report that specific size distributions of vegetation patches indicate overall ecosystem health and function. Using a biocrust (micro-vegetation of mosses, lichens, and cyanobacteria) model system, and multivariate modeling, we determined the relative importance of biodiversity, patch-size distribution, and total abundance to nutrient cycling and multifunctionality. In most cases we explained at least 20%, and up to 65%, of the variation in ecosystem functions, and 42% of the variation in multifunctionality. Species richness was the most important determinant of C cycling, constituting an uncommonly clear link between diversity and function in a non-experimental field setting. Regarding C cycling in gypsiferous soils, we found that patch size distributions with a greater frequency of small to medium patches, as opposed to very small patches, were more highly functional. Nitrogen cycling was largely a function of biocrust cover in two soil types, whereas in gypsiferous soils, more central-tending patch size distributions were less functional with regards to N cycling. All three community properties were about equally important to multifunctionality. Our results highlight the functional role of biotic attributes other than biodiversity, and indicate that high cover and diversity, together with a particular patch-size distribution, must be attained simultaneously to maximize multifunctionality. The results also agree with trends observed with other terrestrial and aquatic communities that more biodiversity is needed to sustain multifunctionality compared to single functions considered independently.     

Biodiversity and ecosystem functioning in naturally assembled communities

Approximately 25 years ago, ecologists became increasingly interested in the question of whether ongoing biodiversity loss matters for the functioning of ecosystems. As such, a new ecological subfield on Biodiversity and Ecosystem Functioning (BEF) was born. This subfield was initially dominated by theoretical studies and by experiments in which biodiversity was manipulated, and responses of ecosystem functions such as biomass production, decomposition rates, carbon sequestration, trophic interactions and pollination were assessed. More recently, an increasing number of studies have investigated BEF relationships in non‐manipulated ecosystems, but reviews synthesizing our knowledge on the importance of real‐world biodiversity are still largely missing. I performed a systematic review in order to assess how biodiversity drives ecosystem functioning in both terrestrial and aquatic, naturally assembled communities, and on how important biodiversity is compared to other factors, including other aspects of community composition and abiotic conditions. The outcomes of 258 published studies, which reported 726 BEF relationships, revealed that in many cases, biodiversity promotes average biomass production and its temporal stability, and pollination success. For decomposition rates and ecosystem multifunctionality, positive effects of biodiversity outnumbered negative effects, but neutral relationships were even more common. Similarly, negative effects of prey biodiversity on pathogen and herbivore damage outnumbered positive effects, but were less common than neutral relationships. Finally, there was no evidence that biodiversity is related to soil carbon storage. Most BEF studies focused on the effects of taxonomic diversity, however, metrics of functional diversity were generally stronger predictors of ecosystem functioning. Furthermore, in most studies, abiotic factors and functional composition (e.g. the presence of a certain functional group) were stronger drivers of ecosystem functioning than biodiversity per se. While experiments suggest that positive biodiversity effects become stronger at larger spatial scales, in naturally assembled communities this idea is too poorly studied to draw general conclusions. In summary, a high biodiversity in naturally assembled communities positively drives various ecosystem functions. At the same time, the strength and direction of these effects vary highly among studies, and factors other than biodiversity can be even more important in driving ecosystem functioning. Thus, to promote those ecosystem functions that underpin human well‐being, conservation should not only promote biodiversity per se, but also the abiotic conditions favouring species with suitable trait combinations.     

羌塘高寒草地物种多样性与生态系统多功能关系格局

传统的生物多样性-生态系统功能研究大多侧重于单一生态系统功能与物种多样性的关系,忽略了生态系统的重要价值在于其能够同时提供多种功能或服务,即生态系统的多功能性。基于藏北羌塘高寒草地样带调查数据,选取植被地上生物量、地下生物量、土壤全氮、硝态氮及铵态氮含量、土壤全磷含量、土壤有机碳储量等7个与植物生长、养分循环、土壤有机碳蓄积相关的参数来表征生态系统多功能性。采用上述参数转换为Z分数后的平均值计算多功能性指数(M)。分析了不同生物多样性指数与生态系统多功能指数的关系以及年降水量和年均温度对物种多样性和生态系统多功能性指数的影响。结果表明,物种丰富度指数与生态系统多功能性之间呈极显著的正相关关系,Shannon-wiener和Simpson物种多样性指数也与多功能性指数间呈显著的正相关,但多功能性指数与Pielou均匀度指数没有表现出明显的相关关系。物种丰富度与表征植物生长、养分循环以及土壤有机碳蓄积的生态系统功能指数间也均呈极显著的正相关关系。降水格局显著影响羌塘高原物种丰富度和生态系统多功能指数,二者均随年降雨量的增加而显著增加,但物种多样性指数并未与年降水量呈现显著相关关系。研究强调了群落物种丰富度即群落物种数量对维持生态系统多功能性的重要意义,这意味着由于人类活动导致的物种丧失可能会给藏北高寒草地生态系统多功能和生态服务带来更为严重的后果。就退化草地恢复或草地可持续管理而言,在藏北羌塘地区,本地植物种的物种丰富度恢复和维持应作为重要目标之一。     

Plant diversity loss reduces soil respiration across terrestrial ecosystems

The rapid global biodiversity loss has led to the decline in ecosystem function. Despite the critical importance of soil respiration (Rs) in the global carbon and nutrient cycles, how plant diversity loss affects Rs remains uncertain. Here we present a meta‐analysis using 446 paired observations from 95 published studies to evaluate the effects of plant and litter mixtures on Rs and its components. We found that total Rs and heterotrophic respiration (Rh) were, on average, greater in plant mixtures than expected from those of monocultures. These mixture effects increased with increasing species richness (SR) in both plant and litter mixtures. While the positive effects of species mixtures remained similar over time for total Rs, they increased over time for Rh in plant mixtures but decreased in litter mixtures. Despite the wide range of variations in mean annual temperature, annual aridity index, and ecosystem types, the plant mixture effects on total Rs and Rh did not change geographically, except for a more pronounced increase of total Rs in species mixtures with reduced water availability. Our structural equation models suggested that the positive effects of SR and stand age on total and Rh were driven by increased plant inputs and soil microbial biomass. Our results suggest that plant diversity loss has ubiquitous negative impacts on Rs, one of the fundamental carbon‐cycle processes sustaining terrestrial element cycling and ecosystem function.