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The vulnerability of trees to insect herbivory can be influenced by forest structure and diversity. Associational resistance theory posits that trees surrounded by diverse neighbours are likely to suffer reduced herbivory. However, the underlying mechanisms of this effect are debated, with accumulating evidence suggesting that leaf traits could mediate the strength and direction of the diversity‐herbivory relationships.To determine the role of tree trait variation in mediating this relationship, we measured leaf herbivory and nine morphological and nutritional leaf traits known to influence herbivory on 394 focal trees of twelve species cultivated in monocultures and mixtures of four, eight, and sixteen species in a 4‐year‐old large‐scale manipulated tree diversity experiment.A reduction in the proportion of focal trees in species‐rich neighbourhoods resulted in increased leaf carbon: nitrogen ratio of focal trees, which mediated a reduction in insect herbivory. Moreover, an increase in plant height apparency, defined as the disparity in total height between a focal tree and its closest neighbours, indirectly amplified herbivory by reducing leaf phosphorus concentration.Synthesis: The study suggests that neighbourhood diversity and physical structure can indirectly affect herbivory on a focal plant by modifying its leaf trait. Accounting for the functional differences between forests could enhance our understanding of diversity–herbivory relationships. [ABSTRACT FROM AUTHOR]

This article discusses a recent study that examines the role of the Tasmanian devil, an endangered species, in nutrient cycling, soil microbial diversity, forest productivity, and carbon storage in Tasmanian Eucalypt forests. The study found that the scavenging traits of the Tasmanian devil, particularly its consumption of bone material, contribute to the mobilization of critical nutrients in the forest ecosystem. The research suggests that the presence of Tasmanian devils and their scat may help buffer the forests from climate-induced changes in soil microbe, nutrient, and carbon cycling processes. These findings highlight the importance of biodiversity in maintaining ecosystem functions and processes, especially in the face of climate change and species loss. [Extracted from the article]

Biodiversity is declining on a global scale with detrimental effects on ecosystem functioning. Effects of reduced tree diversity on the diversity of aboveground animals have been studied in detail, whereas the response of soil animals remains poorly understood. We analyzed seasonal variations of soil oribatid mite communities as major soil detritivores along a tree diversity gradient as implemented in the Biodiversity - Ecosystem Functioning Experiment in China. A total of 24,898 oribatid mites were collected over two years and eight sampling periods. Generally, density and species richness of oribatid mites significantly differed among the four seasons and were highest in winter. By contrast, tree diversity did not significantly affect the density and species richness of oribatid mites as main factor, but its effect varied with season, however, the variations were generally small. Also, oribatid mite community composition varied with seasons but not significantly with tree diversity. Further, functional traits and functional diversity of oribatid mites significantly changed with seasons, but this varied with tree diversity although these variations were small. Overall, the effect of season on soil oribatid mite communities considerably exceeded that of tree diversity, indicating that oribatid mite communities in soil are mainly structured by seasonal variations in abiotic factors and resources outweighing the role of tree diversity. The results highlight the necessity of considering temporal variations when analyzing relationships between plant diversity and soil animal communities.

Previous studies have examined whether the magnitude of tsunami impacts on coastal forests differs according to the density and size structure of the trees. However, few studies have focused on how monoculture/mixed forest settings and tree spatial arrangements in coastal forests can mitigate tsunami impacts. Here, satellite images and aerial photographs taken before and after the tsunami events triggered by the Great East Japan Earthquake on March 11, 2011, were used to compare the degree of damage to coastal forests between monoculture (black pine only) and mixed forests (black pine and other broad-leaved tree species) as well as between forests with different tree planting spatial patterns. We found that mixed coastal forests were less vulnerable to tsunami impacts than were black pine monoculture coastal forests, and that mixed coastal forests with a more complicated spatial structure were less vulnerable than were simply structured mixed forests. The functional complementarity of mixed coastal forests leads to enhanced tree growth and physical stability, which may decrease the vulnerability of these forests to tsunami impacts. Maintaining mixed coastal forests with black pine and increasing forest spatial complexity is critical for the management of coastal forests to mitigate effects of tsunami disasters. [ABSTRACT FROM AUTHOR]

The relationship between biodiversity and ecosystem functioning (BEF) and its intrinsic mechanisms has always been a hot research topic among ecologists. However, there are few recent reviews and syntheses on BEF research. We analyze the annual publication volume, research strength, and research hotspots of the literature about BEF in Web of Science from 2001 to 2021 to explore the current status and future trends. The results showed that the number of publications on BEF research increased steadily from 2001 to 2021, with the initial development stage occurring before 2007 and a steady growth stage from 2008 to 2012, as well as a steady growth trend can be observed in the number of publications. After 2013, it entered a phase of rapid development, with the highest number of publications in 2021, with 596 publications. The studies were mainly conducted in developed countries, such as the USA, England, and France, which outstood in terms of the quantity and quality of literature published. China has the 5th highest number of publications in the world and the strongest growth in the last 5 years. The Centre National De La Recherche Scientifique (CNRS) was the institution with the most publications, while the German Center for Integrative Biodiversity Research (iDIV), the Helmholtz Center for Environmental Research (UFZ), and the Helmholtz Association all accounted for more than 60% of their respective publication volumes in the last 5 years, demonstrating the trend of rapid development in Germany in recent five years. The author with the most publications was Schmid B, while Verheyen K had been more active with 69.23% of the total number of papers published over the previous five years. Ecology was the journal with the most publications among the top 15 journals, but Global Change Biology and PNAS had the highest impact factors and the highest average citation frequency. The BEF hotspots primarily concentrate on biodiversity and its productivity, but with the extinction of species around the world, the effects of climate change, and the loss of biodiversity, it is important to investigate the relationship between biodiversity and ecosystem services. There is a disparity in the number of publications and average citations per article between scholars in China and in European and American countries. However, the number of Chinese publications increased rapidly in the last five years. Furthermore, BEF relationships are anticipated to differ across multiple trophic levels, but this subject has received less attention in terms of animal diversity, belowground biodiversity, and ecosystem multifunctionality within and across ecosystems, which needs to be thoroughly investigated to provide a strong base for the conservation of biodiversity. [ABSTRACT FROM AUTHOR]

Decline in species richness as well as changes in community evenness or functional diversity have been hypothesised to jointly affect ecosystem functioning. However, disentangling the relative effects of these changes in community structure is hard as these different aspects often covary with species richness in real‐world ecosystems. In this study, we investigated the individual and interactive effects of functional diversity and community evenness of predators on the level of control of herbivorous prey.Using a highly replicated mesocosm experiment, we crossed three levels of functional diversity of arthropod predators with two levels of community evenness while controlling for the effect of species richness. Using this experimental setting, we hypothesised that the effect size of functional diversity of predators depends on community evenness. We expected a positive effect of functional diversity of predators on top‐down control at high level of community evenness while we thought that species identity and their associated traits should drive most of the effect on top‐down control at low level of community evenness.Our results did not provide any evidence for an interaction between functional diversity and community evenness nor any beneficial effect of increased functional diversity overall on predation rates of herbivorous prey. In addition, our results revealed that species and functional identity drives most of the effects of predator community composition on top‐down control of their prey in our study system. Assemblages composed of active hunters with low handling time and no starvation ability tended to have the highest impacts on prey biomass.By indicating that top‐down control of herbivorous prey by arthropod predators is mainly driven by species and functional identity and not by functional diversity, our study provides insights into the consequences of ongoing species loss on ecosystem functioning. Future research should now explore the predictability of trophic interactions based on functional traits of predator and herbivorous prey to anticipate the consequences of changes in species composition on ecosystem functioning. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Plant diversity has been found to increase herbivore diversity, including abundance, species richness and phylogenetic diversity. However, it is yet to be established at which spatial scale these effects are strongest, because host finding and community assembly may be shaped by host diversity both in local habitat patches and at larger scales.Using arthropod herbivore data collected from a large biodiversity and ecosystem function experiment in China (BEF‐China), we analysed how habitat patch (individual study plots) and larger‐scale (surrounding study plots) tree diversity relates to species richness, abundance, functional diversity and phylogenetic diversity of herbivore assemblages on focal plants.Tree diversity of both the focal habitat patch and larger‐scale patch neighbourhood affected herbivore diversity patterns and host plant selection, with the effect being greater for the former. Furthermore, focal and neighbouring trees that are phylogenetically related were found more likely to share similar herbivores.Synthesis. By focusing on tree diversity effects of both the local habitat patch and wider patch neighbourhoods, our findings highlight the importance of considering additional scales to give a more nuanced understanding of the mechanisms underlying herbivore community structure and diversity patterns in species‐rich forests. [ABSTRACT FROM AUTHOR]

Increasing species diversity frequently enhances ecosystem functioning - a pattern strengthened with ecosystem age. It has been suggested that strengthened responses over time may be due to community assembly processes and cumulative effects over the history of interactions between and among plant and soil communities. However, most soil studies are conducted with destructive one-time samplings, and little is known about how phenological patterns of soil activity change with biodiversity and ecosystem age. Here, we investigate phenology metrics related to soil detritivore feeding activity (i.e., duration, total magnitude, variability), measured via the bait-lamina method, in a long-term grassland biodiversity experiment that included an experimental removal of plant and soil history, resulting in older and younger assembled plant and soil communities. Detritivore feeding activity peaked in spring and/or early summer, with another short increase in fall. Increased plant species richness enhanced the total magnitude and variability (i.e., the coefficient of variation) of detritivore feeding activity. Plant and soil history enhanced the buffering effects of plant richness on variability, causing older plant and soil communities to have the strongest relationships between plant richness and stability. However, older plant and soil communities showed the shortest duration of detritivore feeding activity, and species richness was not important in changing activity duration. These findings underscore the importance of considering ecosystem age as a critical component that modifies plant diversity effects on ecosystem functioning, with important implications for promoting ecosystem stability and resilience under environmental change. • Invertebrate feeding activity in temperate grassland peaks in summer and fall. • Plant diversity increases the magnitude and stability of invertebrate feeding activity. • Diversity effects on stability are enhanced by plant and soil accumulated history. [ABSTRACT FROM AUTHOR]

Human-induced biodiversity loss negatively affects ecosystem function, but the interactive effects of biodiversity change across trophic levels remain insufficiently understood. We sampled arboreal spiders and lepidopteran larvae across seasons in 2 years in a subtropical tree diversity experiment, and then disentangled the links between tree diversity and arthropod predator diversity by deconstructing the pathways among multiple components of diversity (taxonomic, phylogenetic and functional) with structural equation models. We found that herbivores were major mediators of plant species richness effects on abundance, species richness, functional and phylogenetic diversity of predators, while phylogenetic, functional and structural diversity of trees were also important mediators of this process. However, the strength and direction differed between functional, structural and phylogenetic diversity effects, indicating different underlying mechanisms for predator community assembly. Abundance and multiple diversity components of predators were consistently affected by tree functional diversity, indicating that the variation in structure and environment caused by plant functional composition might play key roles in predator community assembly. Our study highlights the importance of an integrated approach based on multiple biodiversity components in understanding the consequences of biodiversity loss in multitrophic communities. [ABSTRACT FROM AUTHOR]

Species diversity shapes ecosystem services. Despite the advantages that this relationship has for pest management, few studies have investigated the links between infrastructure damage (i.e. the percentage amount of infrastructures infested by termites), species richness and the environment. Moreover, it is not clear that which proportion of species richness (total/functional‐dominant/common/rare) contributes most to infrastructure damage.We correlated termite species richness with termite infestation throughout 83 cities in Zhejiang Province, eastern China. Species were classified according to whether or not they fed on wood, and based upon their distributional range, whether they were common or rare. We analysed the relative importance and the direct/indirect effects of climate, vegetation, anthropogenic activities, and the species richness of four functional categories of termites on the damage levels of eight infrastructure types in populated (i.e. urban and rural building, green space and sea wall) and remote areas (i.e. ancient building, large‐old tree, agroforest and reservoir dam).Common species favoured populated areas, whereas rare species favoured remote areas. Common species, with preferences for deciduous vegetation, caused more damage to the infrastructures of populated areas. Rare species, with preferences for evergreen vegetation, caused more damage in remote areas. Reforestation project which emphasized evergreen trees increased the number of rare species but reduced the number of common species. Elevation and drought risk were positively correlated with rare species richness but neutrally with common species richness.Structural equation models showed that vegetation predominantly influenced infrastructure damage in populated areas via altering common species richness, whereas climate predominantly and directly influenced infrastructure damage in remote areas. Notably, elevation and drought risk were positively correlated with infrastructure damage especially in remote areas.Synthesis and applications. Termites cause global economic losses of 15–40 billion dollars per year. Our study reveals that managing city forests and green space, for example increasing the proportion of evergreen trees, is a sustainable means of suppressing common termites and thereby reducing infrastructure damage in populated areas. Conservation strategies, supported by regular inspections, will become increasingly important as climate change not only threatens the survival of less harmful rare species, but also increases infrastructure damage in remote areas. [ABSTRACT FROM AUTHOR]

Abstract Across the globe, ecological communities are confronted with multiple global environmental change drivers, and they are responding in complex ways ranging from behavioral, physiological, and morphological changes within populations to changes in community composition and food web structure with consequences for ecosystem functioning. A better understanding of global change‐induced alterations of multitrophic biodiversity and the ecosystem‐level responses in terrestrial ecosystems requires holistic and integrative experimental approaches to manipulate and study complex communities and processes above and below the ground. We argue that mesocosm experiments fill a critical gap in this context, especially when based on ecological theory and coupled with microcosm experiments, field experiments, and observational studies of macroecological patterns. We describe the design and specifications of a novel terrestrial mesocosm facility, the iDiv Ecotron. It was developed to allow the setup and maintenance of complex communities and the manipulation of several abiotic factors in a near‐natural way, while simultaneously measuring multiple ecosystem functions. To demonstrate the capabilities of the facility, we provide a case study. This study shows that changes in aboveground multitrophic interactions caused by decreased predator densities can have cascading effects on the composition of belowground communities. The iDiv Ecotrons technical features, which allow for the assembly of an endless spectrum of ecosystem components, create the opportunity for collaboration among researchers with an equally broad spectrum of expertise. In the last part, we outline some of such components that will be implemented in future ecological experiments to be realized in the iDiv Ecotron.

Veteran trees are keystone structures and play vital roles in ecosystems. Tree hollows, which are filled with a mix of leaves and wood that is transformed by the biotic community into wood mould, represent an important microhabitat. Tree hollow communities consist of three major groups of organisms: microbes, mesofauna (nematodes, mites and springtails) and macrofauna (beetles, millipedes and other insects). Little is known about the interplay between associated biota and their importance for decomposition and wood mould production. The aim of this study was to test how initial food web complexity in artificial tree hollows influences community structure, decomposition, and wood mould production. We used large wooden boxes to imitate natural hollows, and mounted them on 20 veteran oaks in Southern Norway. The food webs were manipulated into three levels: (i) a complex community with macrofauna and mesofauna, (ii) a simple community without macrofauna, and (iii) only the defaunated material. Three boxes (one of each treatment, N = 60 boxes) were mounted on each oak and left in the field from May 2017 to October 2019 (28 months). After the field experiment, macrofauna and mesofauna were collected and identified, mass loss in the boxes was determined, and nitrogen and phosphorus concentrations in the wood mould were measured. We found that the complex community treatment had the greatest diversity of beetles and the highest number of predatory macrofauna. The nematodes within the complex community treatment had greater trophic structuring with K‐selected species associated with stable conditions. The nematodes communities also indicated that the complex community had a balanced decomposition pathway, while the simple community was dominated by fungi and the defaunated community by bacteria. Lastly, we found that the boxes with the complex community treatment had the highest overall rate of mass loss, and greater amounts of wood mould with higher concentrations of nitrogen and phosphorus. Our results indicate that macrofauna in artificial hollows increase trophic structuring, enhance decomposition rates and wood mould production, and mediate the decomposition pathway. These findings highlight the importance of food web complexity for promoting biodiversity and ecosystem functioning in veteran tree hollows. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Abstract Global change alters ecological communities with consequences for ecosystem processes. Such processes and functions are a central aspect of ecological research and vital to understanding and mitigating the consequences of global change, but also those of other drivers of change in organism communities. In this context, the concept of energy flux through trophic networks integrates food‐web theory and biodiversity‐ecosystem functioning theory and connects biodiversity to multitrophic ecosystem functioning. As such, the energy‐flux approach is a strikingly effective tool to answer central questions in ecology and global‐change research. This might seem straight forward, given that the theoretical background and software to efficiently calculate energy flux are readily available. However, the implementation of such calculations is not always straight forward, especially for those who are new to the topic and not familiar with concepts central to this line of research, such as food‐web theory or metabolic theory. To facilitate wider use of energy flux in ecological research, we thus provide a guide to adopting energy‐flux calculations for people new to the method, struggling with its implementation, or simply looking for background reading, important resources, and standard solutions to the problems everyone faces when starting to quantify energy fluxes for their community data. First, we introduce energy flux and its use in community and ecosystem ecology. Then, we provide a comprehensive explanation of the single steps towards calculating energy flux for community data. Finally, we discuss remaining challenges and exciting research frontiers for future energy‐flux research.

Abstract Both species (interspecific) richness and genotype (intraspecific) richness of dominant species have significant effects on ecosystem functioning directly or indirectly by regulating plant community functional structure. However, the similarities and differences of the effects between inter‐ and intraspecific levels are poorly understood. In this study, we selected the main species in the semi‐arid Eurasian typical steppe as study objects and simultaneously carried out a species richness experiment and a genotype richness experiment of Stipa grandis which is one of the dominant species in this region. We investigated how plants at each of the two richness levels affected multiple ecosystem functions (biomass, soil C, N and P cycles) directly and indirectly by regulating community functional structure, including community‐weighted mean trait values (CWM) and functional dispersion (FDis). Both species richness and genotype richness showed significant direct effects on soil P cycle, and FDis significantly mediated the responses of aboveground biomass and soil N cycle to the changes of species richness and the response of belowground biomass to the changes of genotype richness in S. grandis. CWM showed significant effects on biomass in the species richness experiment and soil nutrient cycles in the genotype richness experiment, independently of the levels of plant richness. These findings provide experimental insights of intraspecific richness effects into the relationships between biodiversity and ecosystem functioning, and highlight the importance of conserving the intraspecific diversity of dominant species in the semi‐arid steppe regions.

Abstract Studies on the effects of human‐driven forest disturbance usually focus on either biodiversity or carbon dynamics but much less is known about ecosystem processes that span different trophic levels. Herbivory is a fundamental ecological process for ecosystem functioning, but it remains poorly quantified in human‐modified tropical rainforests. Here, we present the results of the largest study to date on the impacts of human disturbances on herbivory. We quantified the incidence (percentage of leaves affected) and severity (the percentage of leaf area lost) of canopy insect herbivory caused by chewers, miners, and gall makers in leaves from 1,076 trees distributed across 20 undisturbed and human‐modified forest plots in the Amazon. We found that chewers dominated herbivory incidence, yet were not a good predictor of the other forms of herbivory at either the stem or plot level. Chewing severity was higher in both logged and logged‐and‐burned primary forests when compared to undisturbed forests. We found no difference in herbivory severity between undisturbed primary forests and secondary forests. Despite evidence at the stem level, neither plot‐level incidence nor severity of the three forms of herbivory responded to disturbance. Synthesis. Our large‐scale study of canopy herbivory confirms that chewers dominate the herbivory signal in tropical forests, but that their influence on leaf area lost cannot predict the incidence or severity of other forms. We found only limited evidence suggesting that human disturbance affects the severity of leaf herbivory, with higher values in logged and logged‐and‐burned forests than undisturbed and secondary forests. Additionally, we found no effect of human disturbance on the incidence of leaf herbivory.

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. [ABSTRACT FROM AUTHOR]

Abstract Background Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment (as of 2018) in Japan. Results I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages (≤ 3 years), the positive complementarity effect was explained by enhanced growths of early- and mid-successional species in the mixture. Later on (≥ 15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e. alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer. Conclusions The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies.

Despite evidence of a positive effect of functional diversity on ecosystem productivity, the importance of functionally distinct species (i.e. species that display an original combination of traits) is poorly understood. To investigate howdistinct species affect ecosystem productivity, we used a forest-gap model to simulate realistic temperate forest successions along an environmental gradient and measured ecosystem productivity at the end of the successional trajectories. We performed 10 560 simulations with different sets and numbers of species, bearing either distinct or indistinct functional traits, and compared them to random assemblages, to mimic the consequences of a regional loss of species. Long-term ecosystem productivity dropped when distinct species were lost first from the regional pool of species, under the harshest environmental conditions. On the contrary, productivity was more dependent on ordinary species in milder environments. Our findings showthat species functional distinctiveness, integrating multiple trait dimensions, can capture species-specific effects on ecosystem productivity. In a context of an environmentally changing world, they highlight the need to investigate the role of distinct species in sustaining ecosystem processes, particularly in extreme environmental conditions. [ABSTRACT FROM AUTHOR]

Across the globe, ecological communities are confronted with multiple global environmental change drivers, and they are responding in complex ways ranging from behavioral, physiological, and morphological changes within populations to changes in community composition and food web structure with consequences for ecosystem functioning. A better understanding of global change‐induced alterations of multitrophic biodiversity and the ecosystem‐level responses in terrestrial ecosystems requires holistic and integrative experimental approaches to manipulate and study complex communities and processes above and below the ground. We argue that mesocosm experiments fill a critical gap in this context, especially when based on ecological theory and coupled with microcosm experiments, field experiments, and observational studies of macroecological patterns. We describe the design and specifications of a novel terrestrial mesocosm facility, the iDiv Ecotron. It was developed to allow the setup and maintenance of complex communities and the manipulation of several abiotic factors in a near‐natural way, while simultaneously measuring multiple ecosystem functions. To demonstrate the capabilities of the facility, we provide a case study. This study shows that changes in aboveground multitrophic interactions caused by decreased predator densities can have cascading effects on the composition of belowground communities. The iDiv Ecotrons technical features, which allow for the assembly of an endless spectrum of ecosystem components, create the opportunity for collaboration among researchers with an equally broad spectrum of expertise. In the last part, we outline some of such components that will be implemented in future ecological experiments to be realized in the iDiv Ecotron. [ABSTRACT FROM AUTHOR]

Both species (interspecific) richness and genotype (intraspecific) richness of dominant species have significant effects on ecosystem functioning directly or indirectly by regulating plant community functional structure. However, the similarities and differences of the effects between inter‐ and intraspecific levels are poorly understood. In this study, we selected the main species in the semi‐arid Eurasian typical steppe as study objects and simultaneously carried out a species richness experiment and a genotype richness experiment of Stipa grandis which is one of the dominant species in this region. We investigated how plants at each of the two richness levels affected multiple ecosystem functions (biomass, soil C, N and P cycles) directly and indirectly by regulating community functional structure, including community‐weighted mean trait values (CWM) and functional dispersion (FDis). Both species richness and genotype richness showed significant direct effects on soil P cycle, and FDis significantly mediated the responses of aboveground biomass and soil N cycle to the changes of species richness and the response of belowground biomass to the changes of genotype richness in S. grandis. CWM showed significant effects on biomass in the species richness experiment and soil nutrient cycles in the genotype richness experiment, independently of the levels of plant richness. These findings provide experimental insights of intraspecific richness effects into the relationships between biodiversity and ecosystem functioning, and highlight the importance of conserving the intraspecific diversity of dominant species in the semi‐arid steppe regions. [ABSTRACT FROM AUTHOR]

Global change alters ecological communities with consequences for ecosystem processes. Such processes and functions are a central aspect of ecological research and vital to understanding and mitigating the consequences of global change, but also those of other drivers of change in organism communities. In this context, the concept of energy flux through trophic networks integrates food‐web theory and biodiversity‐ecosystem functioning theory and connects biodiversity to multitrophic ecosystem functioning. As such, the energy‐flux approach is a strikingly effective tool to answer central questions in ecology and global‐change research. This might seem straight forward, given that the theoretical background and software to efficiently calculate energy flux are readily available. However, the implementation of such calculations is not always straight forward, especially for those who are new to the topic and not familiar with concepts central to this line of research, such as food‐web theory or metabolic theory. To facilitate wider use of energy flux in ecological research, we thus provide a guide to adopting energy‐flux calculations for people new to the method, struggling with its implementation, or simply looking for background reading, important resources, and standard solutions to the problems everyone faces when starting to quantify energy fluxes for their community data. First, we introduce energy flux and its use in community and ecosystem ecology. Then, we provide a comprehensive explanation of the single steps towards calculating energy flux for community data. Finally, we discuss remaining challenges and exciting research frontiers for future energy‐flux research. [ABSTRACT FROM AUTHOR]

From regional to global scales, anthropogenic environmental change is causing biodiversity loss and reducing ecosystem functionality. Previous studies have investigated the relationship between plant diversity and functional insect communities in temperate and also in tropical grasslands and forests. However, few studies have explored these dynamics in subtropical forests. Here, cavity-nesting Hymenoptera and associated parasitoids were collected across a controlled tree diversity experiment in subtropical China to test how predatory wasps, bees and parasitoids respond to tree species richness. Abundance and species richness of predatory wasps and parasitoids were positively correlated with tree species richness, while bee abundance and bee species richness were unrelated to tree species richness. Our results indicate that tree species richness increases the abundance and species richness of important communities such as predators and parasitoids. Moreover, the results highlight the importance of subtropical forests in maintaining abundance and species richness of key functional insect groups. [ABSTRACT FROM AUTHOR]

Abstract Veteran hollow oaks (Quercus spp.) are keystone structures hosting high insect diversity but are declining in numbers due to intensification of land use and the abandonment of traditional management. The loss of this vital habitat is resulting in a reduction of biodiversity, and this likely has consequences for ecosystem functioning, especially if functional diversity is reduced. A considerable amount of research has been done on predictors of beetle taxonomic diversity in veteran oaks, but predictors of functional diversity have remained largely unexplored. The aim of this study was to establish whether the features and surroundings of veteran oaks are related to functional diversity within three functional groups of beetles (decomposers, predators, and flower visitors) and determine whether species richness and functional diversity within the groups are dependent on the same predictors. Sampling was carried out intermittently between 2004 and 2011 on 61 veteran oaks in Southern Norway. Of the 876 beetle species that were collected, 359 were determined to be decomposers, 284 were predators, and 85 were flower visitors. Species richness and functional diversity in all groups were consistently higher in traps mounted on veteran oaks in forests than in open landscapes. However, additional predictors differed between groups, and for species richness and functional diversity. Decomposer species richness responded to tree vitality, while functional diversity responded to habitat connectivity, predator species richness responded to regrowth of shrubs while functional diversity responded to tree circumference, and flower visitor richness and functional diversity did not respond to any additional predictors. Previous studies have found that the features and surroundings of veteran oaks are important for conservation of taxonomic diversity, and the results from this study indicate that they are also important for functional diversity within multiple functional groups.

Mixed‐species forests often enhance the provision of ecosystem functions, both above‐ and below‐ground. Several of these effects are mediated by the amount and spatial distribution of tree tissues. However, previous studies on tree diversity effects on fine‐root biomass (FRB) have returned inconsistent results and did not distinguish between absorptive and transport fine roots. Furthermore, owing to the lack of species‐specific data, it is not well understood whether complementarity or selection effects contribute more to these mixing effects.Here, we analysed tree species mixing effects on fine‐root traits while considering the respective tree species contributions and root functional types. Specifically, we tested whether tree species mixing increases FRB and root length density (RLD) and results in vertical root stratification. We quantified FRB and RLD in 30‐cm deep soil profiles for 13 tree species in mixed and pure stands across four widespread European forest types. The differentiation of different fine‐root species in mixtures allowed us to disentangle complementarity and selection effects.Across all sites, mixtures supported on average less FRB than pure stands, which was reflected in negative complementarity and selection effects. RLD of absorptive fine roots did not change across the soil profile and even increased in the topsoil, which was associated with positive complementarity effects. There was no evidence for vertical root stratification. Conifer proportion, which was mainly associated with selection effects, dampened net diversity effects. Root functional type further influenced tree species mixing effects.Synthesis. Despite the underyielding of FRB in mixtures, overall soil occupation by absorptive fine roots (RLD) did not decrease in mixtures, pointing to morphological root trait adaptations associated with higher resource‐use efficiency. Increased RLD in the most nutrient‐rich layer in mixtures further indicates complementary interactions among species and a greater resource uptake capacity. This work illustrates that considering only one aspect of trait‐functioning relationships, for example, root biomass, may not capture the full effect of plant diversity on ecosystem functioning. The integration of a larger range of relevant traits is required. Moreover, traditional classification of fine roots based on the 2‐mm diameter cut‐off may obscure responses of roots to environmental changes. [ABSTRACT FROM AUTHOR]

Biodiversity can be measured at multiple organizational scales. While traditional studies have focused at taxonomic diversity, recent studies have emphasized the ecological importance of diversity within populations. However, it is unclear how these different scales of diversity interact to determine the consequence of species loss.Here we asked how predator diversity and presence of ontogenetic diversity within predator populations influences community structure. Ontogenetic diversity arises from shifts in the traits and ecology of individuals during ontogeny and it is one of the biggest sources of intraspecific diversity. However, whether it dampens or strengthens the negative consequences of with species loss is poorly understood.To study the interaction of species diversity and ontogenetic diversity, we experimentally manipulated predator species diversity and diversity of developmental stages within focal predator species and analysed their joint effect on predator and prey survival, biomass and prey community structure in experimental pond systems.While individual effects of ontogenetic diversity were often species specific, losing predator species from the community often had a much smaller or no effect on prey survival, biomass or community structure when all predator populations had high ontogenetic diversity. Thus, ontogenetic diversity within populations buffered against some of the consequences of biodiversity loss at higher organizational levels. Because the experiment controlled mean per capita size and biomass across structured versus unstructured populations, this pattern was not driven by differences in biomass of predators. Instead, results suggest that effects were driven by changes in the functional roles and indirect interactions across and within species. This indicates that even if all environmental conditions are similar, differences in the intrinsic structure of populations can modify the consequences of biodiversity loss.Together, these results revealed the importance of ontogenetic diversity within species for strengthening the resilience of natural communities to consequences of biodiversity loss and emphasize the need to integrate biodiversity patterns across organizational scales. [ABSTRACT FROM AUTHOR]

From regional to global scales, anthropogenic environmental change is causing biodiversity loss and reducing ecosystem functionality. Previous studies have investigated the relationship between plant diversity and functional insect communities in temperate and also in tropical grasslands and forests. However, few studies have explored these dynamics in subtropical forests. Here, cavity-nesting Hymenoptera and associated parasitoids were collected across a controlled tree diversity experiment in subtropical China to test how predatory wasps, bees and parasitoids respond to tree species richness. Abundance and species richness of predatory wasps and parasitoids were positively correlated with tree species richness, while bee abundance and bee species richness were unrelated to tree species richness. Our results indicate that tree species richness increases the abundance and species richness of important communities such as predators and parasitoids. Moreover, the results highlight the importance of subtropical forests in maintaining abundance and species richness of key functional insect groups. [ABSTRACT FROM AUTHOR]

Studies on the effects of human‐driven forest disturbance usually focus on either biodiversity or carbon dynamics but much less is known about ecosystem processes that span different trophic levels. Herbivory is a fundamental ecological process for ecosystem functioning, but it remains poorly quantified in human‐modified tropical rainforests.Here, we present the results of the largest study to date on the impacts of human disturbances on herbivory. We quantified the incidence (percentage of leaves affected) and severity (the percentage of leaf area lost) of canopy insect herbivory caused by chewers, miners, and gall makers in leaves from 1,076 trees distributed across 20 undisturbed and human‐modified forest plots in the Amazon.We found that chewers dominated herbivory incidence, yet were not a good predictor of the other forms of herbivory at either the stem or plot level. Chewing severity was higher in both logged and logged‐and‐burned primary forests when compared to undisturbed forests. We found no difference in herbivory severity between undisturbed primary forests and secondary forests. Despite evidence at the stem level, neither plot‐level incidence nor severity of the three forms of herbivory responded to disturbance.Synthesis. Our large‐scale study of canopy herbivory confirms that chewers dominate the herbivory signal in tropical forests, but that their influence on leaf area lost cannot predict the incidence or severity of other forms. We found only limited evidence suggesting that human disturbance affects the severity of leaf herbivory, with higher values in logged and logged‐and‐burned forests than undisturbed and secondary forests. Additionally, we found no effect of human disturbance on the incidence of leaf herbivory. [ABSTRACT FROM AUTHOR]

Aims: The productivity–plant diversity relationship is a central subject in ecology under debate for decades. Anthropogenic disturbances have been demonstrated to affect productivity and plant diversity. However, the impact of disturbances on the productivity–diversity relationship is poorly understood. Location: An old‐field located at the Touch of Nature Environmental Center in Jackson County, Illinois, USA. Methods: A manipulative experiment with fertilizer (unfertilized, fertilized annually, fertilized every five years) and mowing (unmowed, mowed in spring only, mowed in spring and fall) in a successional old‐field began in 1996 to examine disturbance effects on above‐ground net primary productivity (ANPP)–plant diversity relationships. Taxonomic (species richness, T0) and phylogenetic (net relatedness index, NRI) diversity were selected as potential plant diversity metrics. Results: A unimodal relationship of ANPP with T0 and a negative relationship between ANPP and NRI were found across all treatments and years in this study, but individual years showed different patterns. Fertilization did not affect T0, NRI, and ANPP, whereas mowing stimulated T0 and ANPP but reduced NRI (i.e., increasing phylogenetic diversity) across all survey years. New colonists, especially exotic species introduced under mowing, but not locally extinct species, were more distantly related to resident species than by chance, implying that invasion of exotic species contributes to phylogenetic overdispersion of community assembly in the old‐field. However, the patterns of the unimodal relationship of ANPP with T0 and the negative correlation between ANPP and NRI did not change under fertilization or mowing in this study. Conclusions: Anthropogenic disturbances alter productivity and different dimensions of plant diversity, but do not change the patterns of the productivity–diversity relationships. Our findings highlight the robust relationship between productivity and diversity providing empirical support for productivity as a powerful predictor of plant diversity under intensified human activities. [ABSTRACT FROM AUTHOR]

Background: Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment (as of 2018) in Japan. Results: I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages (≤ 3 years), the positive complementarity effect was explained by enhanced growths of early- and mid-successional species in the mixture. Later on (≥ 15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e. alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer. Conclusions: The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies. [ABSTRACT FROM AUTHOR]

While tree diversity has been proven to enhance above‐ground forest biomass in many instances, the effect on below‐ground biomass has often been neutral, or even negative. This raises the questions of whether above‐ground results are the product of a reduced allocation below‐ground in more diverse forests, which could imply a more efficient acquisition of below‐ground resources per unit root, and whether the effects of diversity have been correctly quantified and interpreted in the past.We addressed these issues using data from a tree‐based functional diversity experiment where 24 mixtures and their respective monocultures were analysed in a fully replicated design. We used species‐level measurements of above‐ and below‐ground biomass to assess how adding below‐ground biomass changes our interpretations regarding the roles of complementarity effects (niche partitioning or facilitation between species) and selection effects (dominance of high‐yielding species within mixtures).Mixtures showed overyielding of above‐ground biomass but not below‐ground. Although remaining significantly positive, this translated into diversity effects of a lesser magnitude when adding below‐ground biomass. However, species did not reduce their allocation to below‐ground biomass within mixtures compared to monocultures. Rather, this combination of above‐ground overyielding and below‐ground neutral effect was caused by the dominance in mixtures of species with a low below‐ground allocation strategy. Another consequence of these species dominance is that their actual contribution to total productivity within mixtures was overestimated when using only above‐ground biomass, due to their relatively small below‐ground biomass. This caused an overestimation of the selection or dominance effects, thereby causing an underestimation of the relative importance of complementarity effects.Synthesis. This study emphasizes the need to consider both above‐ and below‐ground biomass components when determining the origin and strength of diversity effects, or when attempting to link tree diversity to ecosystem services such as carbon sequestration. The statistical partitioning of net effects is a widely used method, but one which can lead to an overestimation of the role of individual dominant species when below‐ground biomass is not taken into account, hence diminishing the role of positive interactions between species. [ABSTRACT FROM AUTHOR]

Abstract Herbivores and fungal pathogens are key drivers of plant community composition and functioning. The effects of herbivores and pathogens are mediated by the diversity and functional characteristics of their host plants. However, the combined effects of herbivory and pathogen damage, and their consequences for plant performance, have not yet been addressed in the context of biodiversity–ecosystem functioning research. We analyzed the relationships between herbivory, fungal pathogen damage and their effects on tree growth in a large‐scale forest‐biodiversity experiment. Moreover, we tested whether variation in leaf trait and climatic niche characteristics among tree species influenced these relationships. We found significant positive effects of herbivory on pathogen damage, and vice versa. These effects were attenuated by tree species richness—because herbivory increased and pathogen damage decreased with increasing richness—and were most pronounced for species with soft leaves and narrow climatic niches. However, herbivory and pathogens had contrasting, independent effects on tree growth, with pathogens decreasing and herbivory increasing growth. The positive herbivory effects indicate that trees might be able to (over‐)compensate for local damage at the level of the whole tree. Nevertheless, we found a dependence of these effects on richness, leaf traits and climatic niche characteristics of the tree species. This could mean that the ability for compensation is influenced by both biodiversity loss and tree species identity—including effects of larger‐scale climatic adaptations that have been rarely considered in this context. Our results suggest that herbivory and pathogens have additive but contrasting effects on tree growth. Considering effects of both herbivory and pathogens may thus help to better understand the net effects of damage on tree performance in communities differing in diversity. Moreover, our study shows how species richness and species characteristics (leaf traits and climatic niches) can modify tree growth responses to leaf damage under real‐world conditions.

Interactions between bacteria and microalgae are important for the functioning of aquatic ecosystems, yet interactions based on the biodiversity of these two taxonomic domains have been scarcely studied. Specifically, it is unclear whether a positive biodiversity-productivity relationship in phytoplankton is largely facilitated by niche partitioning among the phytoplankton organisms themselves or whether associated bacterial communities play an additional role in modifying these diversity effects. Moreover, the effects of intraspecific diversity in phytoplankton communities on bacterial community diversity have not been tested. To address these points, we factorially manipulated both species and intraspecific richness of three diatoms to test the effects of diatom species/strain diversity on biomass production and bacterial diversity in algae-bacteria communities. The results show that diatom intraspecific diversity has significant positive effects on culture biomass and the diversity of the associated free-living bacterial community (0.2-3 μm size fraction), which are comparable in magnitude to species diversity effects. However, there were little to no effects of diatom diversity on host-associated bacterial diversity (>3 μm size fraction), or of bacterial diversity on biomass production. These results suggest a decoupling of bacterial diversity from the diatom diversity-productivity relationship and provide early insights regarding the relations between diversity across domains in aquatic ecosystems., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the International Society for Microbial Ecology.)

Veteran hollow oaks (Quercus spp.) are keystone structures hosting high insect diversity but are declining in numbers due to intensification of land use and the abandonment of traditional management. The loss of this vital habitat is resulting in a reduction of biodiversity, and this likely has consequences for ecosystem functioning, especially if functional diversity is reduced. A considerable amount of research has been done on predictors of beetle taxonomic diversity in veteran oaks, but predictors of functional diversity have remained largely unexplored. The aim of this study was to establish whether the features and surroundings of veteran oaks are related to functional diversity within three functional groups of beetles (decomposers, predators, and flower visitors) and determine whether species richness and functional diversity within the groups are dependent on the same predictors. Sampling was carried out intermittently between 2004 and 2011 on 61 veteran oaks in Southern Norway. Of the 876 beetle species that were collected, 359 were determined to be decomposers, 284 were predators, and 85 were flower visitors. Species richness and functional diversity in all groups were consistently higher in traps mounted on veteran oaks in forests than in open landscapes. However, additional predictors differed between groups, and for species richness and functional diversity. Decomposer species richness responded to tree vitality, while functional diversity responded to habitat connectivity, predator species richness responded to regrowth of shrubs while functional diversity responded to tree circumference, and flower visitor richness and functional diversity did not respond to any additional predictors. Previous studies have found that the features and surroundings of veteran oaks are important for conservation of taxonomic diversity, and the results from this study indicate that they are also important for functional diversity within multiple functional groups. [ABSTRACT FROM AUTHOR]

Selective logging has been so extensive that harvested forest now exceeds unlogged areas in most tropical forest regions outside of the Amazon. In response, in Southeast Asia, enrichment planting with dipterocarp tree species is carried out in an attempt to accelerate restoration of forest structure and functioning. However, assessing the impacts of degradation (from selective logging and other causes) and subsequent restoration with field measurements is expensive and time-consuming. There is therefore a need to develop methods for the assessment of forest quality using remote sensing. Here, we use high spatial resolution satellite imagery and advanced remote sensing products to monitor the pattern and dynamics of estimated vegetation cover, Leaf Area Index (LAI), and the biomass of plots within a field-scale (500 ha) replicated and randomized manipulation that compares different forest restoration treatments with naturally regenerating controls within the Sabah Biodiversity Experiment (SBE). We also compare the biodiversity experiment plots with the surrounding area of the Malua Forest Reserve that was selectively logged for the second time in 2007. In general, satellite remote sensing detected differences in degradation between the once- and twice-logged areas as well as between the different experimental restoration treatments. We found that approximately 70% of the Malua Forest Reserve experienced a decrease of vegetation cover after the selective relogging in 2007, while the Sabah Biodiversity Experiment area that was not relogged showed increasing vegetation cover. Within the experiment, we found that plots restored using Enrichment line planting, had higher remote sensed vegetation cover (Mean ± SE: 66.90 ± 0.06 vs. 61.96 ± 0. 16) and LAI (Mean ± SE: 5.09 ± 0.03 vs. 4.61 ± 0.11) than that of unenriched plots. Among the enrichment planted plots, those planted with mixtures of (4 or 16) species exhibited higher vegetation cover (Mean ± SE: 67.72 ± 0.06 vs. 65.35 ± 0. 09) and LAI (Mean ± SE: 5.29 ± 0.04 vs. 4.82 ± 0.06) than that of monoculture plots. Overall, when our test case of the Sabah Biodiversity Experiment was viewed through the lens of remote sensing indicators, satellite imagery was able to detect changes in forest quality due to selective logging and restoration enrichment planting. Furthermore, our results suggest that diverse mixtures of planted tree seedlings enhance restoration of forest canopies compared to planting with single species. Confirmation with ground data will be needed to validate these results and to better understand the biological processes determining tropical forest degradation and restoration. [ABSTRACT FROM AUTHOR]

Plant diversity loss can alter higher trophic‐level communities via non‐random species interactions, which in turn may cascade to affect key ecosystem functions. These non‐random linkages might be best captured by patterns of phylogenetic diversity, which take into account co‐evolutionary dependencies. However, lack of adequate phylogenetic data of higher trophic levels hampers our mechanistic understanding of biodiversity relationships in species‐rich ecosystems.We used DNA barcoding to generate data on the phylogenetic diversity of lepidopteran caterpillars in a large‐scale forest biodiversity experiment in subtropical China. We analysed how different metrics of lepidopteran phylogenetic diversity (Faith's PD, MPD, MNTD) and taxonomic diversity were influenced by multiple components of tree diversity (taxonomic, functional, phylogenetic).Our data from six sampling periods represent 7,204 mitochondrial cytochrome c oxidase subunit I (COI) sequences of lepidopteran larvae, clustered into 461 molecular operational taxonomic units. Lepidopteran abundance, the effective number of species (irrespective of the focus on rare or common species) and Faith's PD and MPD (reflecting basal evolutionary splits), but not MNTD (reflecting recent evolutionary splits), significantly increased with experimentally manipulated tree species richness. Lepidopteran MNTD decreased with increasing tree MNTD. Path analyses showed that tree phylogenetic and functional diversity explained part, but not all of the effects of tree species richness on lepidopteran diversity. Importantly, tree diversity effects on lepidopteran diversity were to a large extent indirect, operating via changes in lepidopteran abundance.Synthesis. Our study shows that evolutionary dependencies determine the response of herbivore communities to changes in host plant diversity. Incorporating a wider range of diversity metrics both at the level of producers and consumers can thus help to develop a more comprehensive understanding of the functional consequences of biodiversity change across trophic levels. Moreover, the dependence of trophic linkages on herbivore abundances underlines the need to address the consequences of current declines in insect abundances for ecosystem structure and functioning. [ABSTRACT FROM AUTHOR]

Forest productivity may be determined not only by biodiversity but also by environmental factors and stand structure attributes. However, the relative importance of these factors in determining productivity is still controversial for subtropical forests.Based on a large dataset from 600 permanent forest inventory plots across subtropical China, we examined the relationship between biodiversity and forest productivity and tested whether stand structural attributes (stand density in terms of trees per ha, age and tree size) and environmental factors (climate and site conditions) had larger effects on productivity. Furthermore, we quantified the relative importance of environmental factors, stand structure and diversity in determining forest productivity.Diversity, together with stand structure and site conditions, regulated the variability in forest productivity. The relationship between diversity and forest productivity did not vary along environmental gradients. Stand density and age were more important modulators of forest productivity than diversity.Synthesis. Diversity had significant and positive effects on productivity in species‐rich subtropical forests, but the effects of stand density and age were also important. Our work highlights that while biodiversity conservation is often important, the regulation of stand structure can be even more important to maintain high productivity in subtropical forests. [ABSTRACT FROM AUTHOR]

A growing body of empirical evidence has suggested that biodiversity affects the simultaneous performance of multiple ecosystem functions (i.e. ecosystem multifunctionality). Given increasing environmental variability and uncertainty under global change, an emerging question is how biodiversity influences the stability of multiple functions (i.e. multifunctional stability). We currently know little, however, about the determinants and mechanisms of multifunctional stability, which is of practical importance for ensuring the sustainable provision of multiple functions.Here, we examined mechanisms contributing to stability (quantified as the ratio of the mean to the standard deviation) of multiple functions related to ecosystem productivity and carbon sequestration, including plant above‐ground and below‐ground productivity, litter production, gross primary productivity and ecosystem respiration, in a large grassland biodiversity experiment in Inner Mongolia.We found that community‐wide species asynchrony was a strong driver to stabilize multiple functions. Community‐wide asynchrony mediated the positive effects of species richness and response diversity (describing how species with similar effects on ecosystem function respond differently to environmental change) on multifunctional stability. However, species richness had a negative direct effect on multifunctional stability because, although it increased the averaged temporal mean of multiple functions, it strongly increased the averaged temporal standard deviation of multiple functions. The overall effects of species richness on multifunctional stability were thus negative, whereas those of response diversity were positive.Synthesis. The studied ecosystem functions related to ecosystem productivity and carbon sequestration are important in natural grasslands across the world. We conclude that species asynchrony and response diversity, rather than species richness, are key to the ecosystem multifunctional stability. The loss of response diversity and compensatory mechanisms would likely reduce the long‐term sustainability of grasslands in the face of global change. [ABSTRACT FROM AUTHOR]

Summary: Insect herbivore damage and abundance are often reduced in diverse plant stands. However, few studies have explored whether this phenomenon is a result of plant diversity effects on host plant traits.We explored indirect effects of tree species diversity on herbivory via changes in leaf traits in a long‐term forest diversity experiment in Finland. We measured 16 leaf traits and leaf damage by four insect guilds (chewers, gall formers, leaf miners and rollers) on silver birch (Betula pendula) trees growing in one‐, two‐, three‐ and five‐species mixtures.A decline in the frequency of birch in mixed stands resulted in reduced leaf area. This, in turn, mediated the reduction in chewing damage in mixed stands. In contrast, associational resistance of birch to leaf miners was not trait‐mediated but driven directly by concurrent declines in birch frequency as tree species richness increased.Our results show that leaf trait variation across the diversity gradient might promote associational resistance, but these patterns are driven by an increase in the relative abundance of heterospecifics rather than by tree species richness per se. Therefore, accounting for concurrent changes in stand structure and key foliar traits is important for the interpretation of plant diversity effects and predictions of associational patterns. [ABSTRACT FROM AUTHOR]

Abstract Researches on the context dependence of biodiversity and ecosystem functioning (BEF) reveal the variation of diversity-productivity relationship (DPR) under stressful environment. The "habitat sampling effect" (HSE) is proposed as the dominant species interaction mechanism at stressful environment, whereas its potential role in driving the DPR has never been testified before. We constructed an individual-based simulation model to explore the variation of DPR along environmental stress gradient, and evaluated the contribution of HSE in explaining this variation. Our results indicated that DPR changed from positive to negative along environmental stress gradients. An unimodal DPR curve emerged at stressful environment, which was caused by the counterbalance of two opposite impacts of HSE on community productivity. At low richness level, the positive impact of HSE on community productivity dominated through the promotion of community size, which resulted in the positive DPR. Whereas with the increase of richness, the negative impact of HSE dominated instead through the reducing of individual productivity, which caused the decreasing part of unimodal curve. Our results highlight the complex characteristic of BEF relationship at stressful environment, and emphasize the necessity of biodiversity in maintaining community's functioning at stressful environment which are often sparse in species richness. Highlights • An unimodal DPR curve emerged at stressful environment. • Positive impact of HSE dominated at low richness level. • Negative impact of HSE dominated with the increase of richness. • Revealing the complex characteristic of BEF relationship at stressful environment. [ABSTRACT FROM AUTHOR]

Productivity‐diversity relationships (P/D) are a vital theme in ecology, but productivity is typically not measured directly in that research. Instead, biomass (B) is the most common proxy for productivity, often as a 1:1 substitute. Unfortunately, this practice may cause error and uncertainty in P/D research, due to the fundamental difference between B and P and variable P/B ratios among and within systems. As a result, P/D research often measures a B/D relationship but interprets it as P/D. Fortunately, plausible, statistically legitimate and predictive P/B relationships can be found with careful analyses based on model selection of alternative allometric scaling equations and tests of model assumptions. Analyses are presented here for P/B relationships of 19 data sets, ranging from plant and animal populations and assemblages to ecosystems and biomes, representing over 2,300 analyzed P/B data. Models included standardized major regression (SMA) and ordinary least squares (OLS) regressions. Simple linear 1:1 P/B relationships are never supported. Instead, logP‐logB transformed data, consistent with allometric scaling approaches, are far more common as the most plausible, statistically legitimate and predictive models. Given these relationships, many P/D studies with only B data may now better estimate P with SMA models, while studies with P and B data in some plots may estimate P in parallel plots with B and D data by using OLS models. Two grassland examples are re‐analyzed to evaluate the importance of this approach to P/D research when B was used as a proxy for P; in one case, P had been underestimated by 20%; in the other case, P had been overestimated by 20%. The difference is related to underlying sampling methods and obtained data. The approach presented here may help productivity‐diversity research resolve some uncertainty to better understand effects of ecological diversity on biomass production.

Biodiversity and ecosystem functioning (BEF) research advocates that biodiversity loss has a drastic alteration on ecosystem functioning. However, studies have barely investigated how the evolutionary dependence of species traits affects EF. Here, we developed an integrated approach combining functional (FD) and phylogenetic diversity (PD) into a single space to disentangle the effects of diversity on leaf decomposition. We conducted an experiment manipulating plant leaves into litterbags containing four species (from a pool of 27) combined in four different treatments represented by low or high FD and PD; these treatments present different scenarios of trait evolution and, therefore, a treatment with high FD and low PD, for instance, mimics a community assembled by divergent trait evolution of close relatives. We found that leaf decomposition was 30% slower in pools with high FD and PD. We show species pool with higher FD and PD have non-additive effects on decomposition, which means there is a negative effect of mixtures combining species with great functional and evolutionary differences. In addition, interactive effects of PD and FD were more important to leaf decomposition than their isolated effects. Our results suggest that PD and FD have interactive effects on decomposition and represent different axes of ecosystem variation, indicating we should avoid using phylogenies as a proxy for functional diversity. We argue that future BEF experiments may alter their design by considering a multifaceted scenario investigating community effects on ecosystem functioning, and idiosyncratic effects of key traits which may determine community assembly and ecosystem processes. [ABSTRACT FROM AUTHOR]

A positive relationship between tree diversity and forest productivity is reported for many forested biomes of the world. However, whether tree diversity is able to increase the stability of forest growth to changes in climate is still an open question. We addressed this question using 36,378 permanent forest plots from National Forest Inventories of Spain and Québec (Eastern Canada), covering five of the most important climate types where forests grow on Earth and a large temperature and precipitation gradient. The plots were used to compute forest productivity (aboveground woody biomass increment) and functional diversity (based on the functional traits of species). Divergence from normal levels of precipitation (dryer or wetter than 30-year means) and temperature (warmer or colder) were computed for each plot from monthly temperature and precipitation means. Other expected drivers of forest growth were also included. Our results show a significant impact of climate divergences on forest productivity, but not always in the expected direction. Furthermore, although functional trait diversity had a general positive impact on forest productivity under normal conditions, this effect was not maintained in stands having suffered from temperature divergence (i.e., warmer conditions). Contrary to our expectations, we found that tree diversity did not result in more stable forest’s growth conditions during changes in climate. These results could have important implications for the future dynamics and management of mixed forests worldwide under climate change. [ABSTRACT FROM AUTHOR]

Abstract: The use of pesticides within agricultural ecosystems has led to wide concern regarding negative effects on the environment. One possible alternative is the use of predators of pest species that naturally occur within agricultural ecosystems. However, the mechanistic basis for how species can be manipulated in order to maximize pest control remains unclear. We carried out a meta‐analysis of 51 studies that manipulated predator species richness in reference to suppression of herbivore prey to determine which components of predator diversity affect pest control. Overall, functional diversity (FD) based on predator's habitat domain, diet breadth and hunting strategy was ranked as the most important variable. Our analysis showed that increases in FD in polycultures led to greater prey suppression compared to both the mean of the component predator species, and the most effective predator species, in monocultures. Further analysis of individual traits indicated these effects are likely to be driven by broad niche differentiation and greater resource exploitation in functionally diverse predator communities. A decoupled measure of phylogenetic diversity, whereby the overlap in variation with FD was removed, was not found to be an important driver of prey suppression. Our results suggest that increasing FD in predatory invertebrates will help maximize pest control ecosystem services in agricultural ecosystems, with the potential to increase suppression above that of the most effective predator species. [ABSTRACT FROM AUTHOR]

Abstract: Overyielding in mixed‐species forests has been demonstrated in a vast body of literature, and the focus of functional biodiversity research is now shifting towards a mechanistic understanding of these observations. We explored diversity–productivity relationships at two sites of a large‐scale tree diversity experiment, with harsh (Ged) and benign (Zed) environmental conditions for plantation establishment. Additive partitioning methodologies were adopted to detect phenomenological patterns in the productivity data, and the trait structure of mixed communities was used to advance insights into compositional effects. After 6 years of plantation development, biomass productivity was significantly higher in mixtures compared to the monocultures of component species. We observed that processes operated through direct tree–tree interactions, as the diversity signal disappeared where trees in mixed stands were surrounded by conspecific neighbours only. This result is particularly relevant for mixed‐species plantation systems, as trees are commonly planted in monospecific patches to simplify management. Partitioning unveiled strong selection effects at both plantation sites. However, at the harsh Ged‐site this was caused by competitive dominance of species with fast young growth, whereas at the benign Zed‐site, species with slow young growth improved their performances but not at the expense of others (i.e. trait‐dependent complementarity). Species tolerance to shading is an influential trait for predicting biodiversity effects, with community‐weighted means in shade tolerance mediating dominance effects (Ged) and functional diversity in shade tolerance mediating (trait‐dependent) complementarity effects (Zed). Synthesis. This study highlights that biodiversity effects in young tree plantations could be explained by the functional composition of mixed communities, with a key role for species levels of shade tolerance. As contrasting results between plantation sites were observed, future research should target the context‐dependency of diversity–productivity relationships. [ABSTRACT FROM AUTHOR]

Reforestation with multiple tree species is a promoted strategy to mitigate global change and to improve forest resistance against natural hazards. Dryland reforestation often fails because seedlings suffer from harsh conditions in degraded areas. Positive species interactions can overcome recruitment drawbacks by ameliorating environmental stress, but there is a strong need to advance functional insights from well-designed experiments. We studied the vitality of 19,712 tree seedlings from 12 species in a Mediterranean common garden experiment (Sardinia). Vitality was assessed as an integrated index of foliage discoloration and defoliation measures, which are in dry areas potential indicators of early plant performance. The experimental design properly replicated all monocultures and a selection of mixed communities with different levels of species richness (SR) and functional diversity (FD). From the second year onwards, a water availability treatment (irrigated versus non-irrigated) was added to the design. In the second year, seedling vitality was strongly determined by species identity and irrigation, but ecological interactions between trees were not relevant. In the third year, however, broad-leaved species were significantly more vigorous in mixed assemblages. Importantly, FD was identified as a seven times stronger predictor compared to SR. This suggests that a certain degree of trait diversification is essential to benefit from facilitative interactions. The positive FD effects were principally mediated by the presence of pines ( P. pinea , P. pinaster and P. halepensis ) in the neighborhood of broad-leaved trees. The latter had, on average, a 23% greater likelihood to have the highest vitality score in mixture with pines. The creation of a favorable physical and biotic neighborhood by pines is likely caused by their fast juvenile growth and adequate crown light transmission. FD effects on seedling vitality were positive, but contrary to the stress-gradient hypothesis, they were of similar magnitude in both irrigated and non-irrigated blocks. We conclude that local neighborhood facilitation provides essential assistance for broad-leaved trees passing a critical seedling stage in semi-arid regions. This knowledge can contribute to increased success rates in forest rehabilitation in these regions. [ABSTRACT FROM AUTHOR]

Abstract Resource subsidies and biodiversity are essential for maintaining community structure and ecosystem functioning, but the relative importance of consumer diversity and resource characteristics to decomposition remains unclear. Forested headwater streams are detritus‐based systems, dependent on leaf litter inputs from adjacent riparian ecosystems, and decomposition of these resources is an important ecosystem function. Here, we examined the effects of consumer community diversity on leaf decomposition in a reciprocal transplant experiment. We asked (1) whether stream consumer communities are adapted to local resources and (2) how functional trait diversity among communities affects the leaf decomposition process. We did not find evidence that communities were adapted to locally derived resource subsidies. Instead, we found that consumer biomass and functional trait diversity as well as resource characteristics were the primary biotic drivers of decomposition. Consumer biomass was stimulated by specific resource subsidies, leading to direct and indirect effects of resource subsidies on ecosystem functioning. Contrary to current theory, we show that decomposition was higher with decreased detritivore functional diversity, suggesting dominant traits encompassing a specific niche increased decomposition. We also show that top‐down, consumer diversity effects can be equal in magnitude to the bottom‐up effects of resource characteristics during the decomposition process. Our research illustrates the importance of considering multiple biotic and abiotic drivers interacting via multiple pathways to affect a crucial ecosystem function.

Herbivores and fungal pathogens are key drivers of plant community composition and functioning. The effects of herbivores and pathogens are mediated by the diversity and functional characteristics of their host plants. However, the combined effects of herbivory and pathogen damage, and their consequences for plant performance, have not yet been addressed in the context of biodiversity-ecosystem functioning research. We analyzed the relationships between herbivory, fungal pathogen damage and their effects on tree growth in a large-scale forest-biodiversity experiment. Moreover, we tested whether variation in leaf trait and climatic niche characteristics among tree species influenced these relationships. We found significant positive effects of herbivory on pathogen damage, and vice versa. These effects were attenuated by tree species richness-because herbivory increased and pathogen damage decreased with increasing richness-and were most pronounced for species with soft leaves and narrow climatic niches. However, herbivory and pathogens had contrasting, independent effects on tree growth, with pathogens decreasing and herbivory increasing growth. The positive herbivory effects indicate that trees might be able to (over-)compensate for local damage at the level of the whole tree. Nevertheless, we found a dependence of these effects on richness, leaf traits and climatic niche characteristics of the tree species. This could mean that the ability for compensation is influenced by both biodiversity loss and tree species identity-including effects of larger-scale climatic adaptations that have been rarely considered in this context. Our results suggest that herbivory and pathogens have additive but contrasting effects on tree growth. Considering effects of both herbivory and pathogens may thus help to better understand the net effects of damage on tree performance in communities differing in diversity. Moreover, our study shows how species richness and species characteristics (leaf traits and climatic niches) can modify tree growth responses to leaf damage under real-world conditions. [ABSTRACT FROM AUTHOR]