Biodiversity-ecosystem Functioning Research Articles

Biodegradable microplastics induce profound changes in lettuce (Lactuca sativa) defense mechanisms and to some extent deteriorate growth traits

The development of agricultural technologies has intensified the use of plastic in this sector. Products of plastic degradation, such as microplastics (MPs), potentially threaten living organisms, biodiversity and agricultural ecosystem functioning. Thus, biodegradable plastic materials have been introduced to agriculture. However, the effects of biodegradable plastic substitutes on soil ecosystems are even less known than those of traditional ones. Here, we studied the effects of environmentally relevant concentrations of MPs prepared from a biodegradable plastic (a starch-polybutylene adipate terephthalate blend, PBAT-BD-MPs) on the growth and defense mechanisms of lettuce (Lactuca sativa) in CLIMECS system (CLImatic Manipulation of ECosystem Samples). PBAT-BD-MPs in the highest concentrations negatively affected some traits of growth, i.e., dry weight percentage, specific leaf area, and both C and N contents. We observed more profound changes in plant physiology and biochemistry, as PBAT-BD-MPs decreased chlorophyll content and triggered a concerted response of plant defense mechanisms against oxidative stress. In conclusion, exposure to PBAT-BD-MPs induced plant oxidative stress and activated plant defense mechanisms, leading to oxidative homeostasis that sustained plant growth and functioning. Our study highlights the need for in-depth understanding of the effect of bioplastics on plants.

Application of Bayesian Causal Inference in the Study of the Relationship Between Biodiversity and Aboveground Biomass of Subtropical Forest in Eastern China

The relationship between biodiversity and ecosystem function is crucial for understanding the structure and processes of subtropical forest ecosystems. However, the extent to which biodiversity influences subtropical forest biomass remains unclear. This study applies Bayesian causal inference to explore causal relationships between forest Aboveground Biomass (AGB) and its potential driving factors (biodiversity factors, biotic factors and abiotic factors) based on Huangshan Forest Dynamics Plots. Furthermore, hypothetical interventions are introduced to these driving factors within the causal network to estimate their potential impact on AGB. The causal relationship network reveals that species diversity and functional diversity are the most direct factors influencing AGB, whereas phylogenetic diversity exerts only an indirect effect. Biotic and abiotic factors also contribute indirect effects on AGB, potentially by influencing other mediating indexes. Intervention analysis shows that with low-level interventions on direct influencing factors, the probability of low AGB is as high as 84%. As the intervention level increases to high, the probability of low AGB decreases by 36%. Moreover, AGB demonstrates a particularly sensitive response to changes in Rao’s quadratic entropy (RaoQ) intervention levels, more so than to other factors, highlighting its critical role in maintaining forest biomass. Therefore, we contend that functional diversity, due to its direct reflection of species’ roles in ecosystem processes, is a more accurate measure of the impact of biodiversity on biomass compared to species or phylogenetic diversity and the interplay between abiotic and biotic factors and biodiversity should not be overlooked. This approach offers a powerful tool for exploring causal relationships, thereby providing a more nuanced and accurate understanding of the relationship between biodiversity and forest ecosystem function.

A spatial matrix factorization method to characterize ecological assemblages as a mixture of unobserved sources: An application to fish eDNA surveys

Abstract Understanding how ecological assemblages vary in space and time is essential for advancing our knowledge of biodiversity dynamics and ecosystem functioning. Metabarcoding of environmental DNA (eDNA) is an efficient method for documenting biodiversity changes in both marine and terrestrial ecosystems. However, current methods fail to detect and display the biodiversity structure within and between eDNA samples limiting ecological and biogeographical interpretations. We present a spatial matrix factorization method that identifies optimal eDNA sample assemblages—called pools—assuming that taxonomic unit composition is based on a fixed number of unknown sources. These sources, in turn, represent taxonomic units sharing similar habitat properties or characteristics. The method aims to reduce the multi‐taxa composition structure into a low number of dimensions defined by these sources. This method is inspired by admixture analysis in population genetics. Using a marine fish eDNA survey on 263 sampling stations detecting 2888 molecular operational taxonomic units (MOTUs), we apply this method to analyse the biogeography and mixing patterns of fish assemblages at regional and large scales. At large scale, our analysis reveals six primary pools of fish samples characterized by distinct biogeographic patterns, with some mixtures between these pools. We identify pools composed of unique sources, corresponding to distinct and more isolated regions such as the Mediterranean and Scotia Seas. We also identify pools composed of a greater mix of sources, corresponding to geographically connected areas, such as tropical regions. Additionally, we identify the taxa underpinning the formation of each pool. In the regional analysis of Mediterranean eDNA samples, our method successfully identifies different pools, allowing the detection of not only geographic gradients but also human‐induced gradients corresponding to protection levels. Spatial matrix factorization adds a new method in community ecology, where each sample is considered as a mixture of K unobserved sources, to assess the dissimilarity of ecological assemblages revealing environmental and human‐induced gradients. Beyond the study of fish eDNA samples, this method has the potential to shed new light on any biodiversity survey and provide new bioindicators of global change.

Regenerative soil management practices no‐till and sheep grazing induce significant but contrasting short‐term changes in the vineyard soil microbiome

Societal Impact StatementWinegrape production is an essential cultural heritage and economic engine of many regions of the world. Regenerative management, which is gaining traction with industry and consumers alike, relies on soil biodiversity for agroecosystem function, reducing external inputs and increasing ecosystem resilience to climate change. We evaluated the effects of no‐till and sheep integration on vineyard soil biodiversity and soil ecosystem function. No‐till had stronger effects on microbial diversity, while sheep grazing stimulated microbial functioning. By providing a better understanding of the practices, we provide fundamental information for growers that want to embrace regenerative principles, ultimately contributing to the sustainability and resilience of the winegrape industry.Summary Regenerative management aims to optimize soil microbial function and diversity for enhanced agroecosystem functionality. Understanding the effects of management practices on soil microorganisms is crucial in the context of growing societal interest in this type of management. This study evaluated the short‐term effects of two soil conservation practices: sheep grazing and no‐till, on abundance, diversity, activity, and network complexity of prokaryotes and fungi in a vineyard soil. Four treatments were applied for 3 years: (1) grazed and tilled, (2) grazed and non‐tilled, (3) non‐grazed and tilled, and (4) non‐grazed and non‐tilled. We hypothesized that stacking of conservation practices (grazing and no‐till) would increase microbial diversity, function, and network complexity. Grazing had strong effects on microbial function, increasing the α‐glucosidase, β‐glucosidase, cellulase, phosphatase, and β‐xylosidase enzymatic activity by 82%, 48%, 61%, 39%, and 55%, respectively, compared to non‐grazed soils, while not causing significant changes in soil microbial diversity. Tillage had strong effects on soil prokaryotic and fungal diversity. For prokaryotes, significant interactions in alpha diversity were found between tillage and grazing, and between tillage and sampling location (tractor row and under vine). Fungal Shannon diversity index was higher in the subsoil (15–30 cm) while a significant interaction between depth, location, tillage, and grazing was found for the Chao‐1 index. Microbial network properties were only significantly affected by sampling depth. This study shows that the lack of disturbance in non‐tilled and non‐grazed soils resulted in a more diverse soil community, while grazing stimulated microbial function, thus showing a decoupling between diversity and function in vineyard soil ecosystems.

Below‐ground traits, rare species and environmental stress regulate the biodiversity–ecosystem function relationship

Abstract Understanding the relationship between biodiversity and ecosystem functioning (BEF) is crucial to predicting the consequences of ongoing global biodiversity loss. However, what drives BEF relationships in natural ecosystems under globally changing conditions remains poorly understood. To address this knowledge gap, we applied a trait‐based approach to data from coastal dune plant communities distributed along a natural environmental stress gradient. Specifically, we compared the relative importance of below‐ground and above‐ground traits in predicting productivity, decomposition, water regulation, carbon stock and nutrient pools, and tested how these BEF relationships were modulated by environmental stress and the presence of rare species that are typically excluded from experimental systems. Below‐ground traits were just as important as above‐ground traits in driving ecosystem functioning. Moreover, despite having low abundances, rare species positively influenced ecosystem multifunctionality (EMF). However, most biodiversity effects became weaker as environmental stress increased. Our study shows that to understand variation in ecosystem functioning we must consider below‐ground traits as much as above‐ground ones. Moreover, it highlights the importance of conserving rare species for maintaining EMF. However, our findings also suggest that rapid global change could dampen the positive effects of diversity on ecosystem functioning. Read the free Plain Language Summary for this article on the Journal blog.

Evolutionary diversity impacts tropical forest biomass and productivity through disturbance‐mediated ecological pathways

Abstract Significant research efforts have been made to uncover links between biodiversity and biomass productivity in forest ecosystems. However, the causal link between these two ecosystem components, and the underlying mediation role of disturbance, are yet poorly understood for hyper‐diverse tropical forests, because multiple ecological mechanisms are sequentially or simultaneously in play, leading to contradictory results in observational studies. Here, we introduce a novel framework for inferring the expected effects of evolutionary diversity on biomass stocks and productivity within forest ecosystems using observational field data. This framework involves an analytical decomposition of stand biomass into three key components: the number of trees, the mean size of trees and the mean wood density. Through this approach, we can distinguish structure‐ and compositional‐based diversity effects, which likely have distinct ecological origins. We tested this framework in one of the oldest tropical forest experiments, where different levels of silvicultural disturbances were applied in the 1980s, with regular monitoring since then. Our results revealed that disturbance history mediates the effect of evolutionary diversity on forest biomass dynamics and that several Biodiversity Ecosystem Function (BEF) relationships may be hidden behind the composite biomass variable. We specifically found an overall significant negative relationship between evolutionary diversity and biomass productivity soon after disturbances (~5–8 years), mostly via mean tree size, despite a positive evolutionary diversity effect on mean wood density. This result reflects that the productivity of disturbed forests is driven by a few dominant and disturbance‐prone species with low wood density and large potential stature, and not by niche complementarity among species. However, these effects rapidly vanished with time, with non‐significant overall effect of evolutionary diversity on productivity both ~30 years after disturbance and in the undisturbed plots. Synthesis. By disentangling the effects of evolutionary diversity on the different components of forest biomass, our framework unveiled how evolutionary diversity impacts forest productivity through different ecological mechanisms, and suggests that it plays a major role, albeit mainly negative, only soon after a disturbance.

More diverse rhizobial communities can lead to higher symbiotic nitrogen fixation rates, even in nitrogen-rich soils.

Symbiotic nitrogen (N) fixation (SNF) by legumes and their rhizobial partners is one of the most important sources of bioavailable N to terrestrial ecosystems. While most work on the regulation of SNF has focussed on abiotic drivers such as light, water and soil nutrients, the diversity of rhizobia with which individual legume partners may play an important but under-recognized role in regulating N inputs from SNF. By experimentally manipulating the diversity of rhizobia available to legumes, we demonstrate that rhizobial diversity can increase average SNF rates by more than 90%, and that high rhizobial diversity can induce increased SNF even under conditions of high soil N fertilization. However, the effects of rhizobial diversity, the conditions under which diversity effects were the strongest, and the likely mechanisms driving these diversity effects differed between the two legume species we assessed. These results provide evidence that biodiversity-ecosystem function relationships can occur at the scales of an individual plant and that the effects of rhizobial diversity may be as important as long-established abiotic factors, such as N availability, in driving terrestrial N inputs via SNF.

Multifaceted biological indicators reveal an effective conservation scheme for marine protected areas

Marine protected areas are set up across the globe to safeguard biodiversity and support coastal ecosystem functioning. In Hong Kong, partially protected marine parks and a no-take marine reserve have been managed under legislation for years, yet a comprehensive evaluation of their conservation impact is still pending despite the region’s reputation for high marine diversity. Most studies assess conservation effectiveness solely in terms of taxonomic diversity, without delving into the contributions of functional and phylogenetic diversity. In this study, we used environmental DNA combined with multifaceted diversity indicators to assess the impact of the level of protection on the fish community in Hong Kong waters. Our results indicated that the marine protected areas significantly contributed to fish community conservation. The no-take marine reserve exhibited the highest taxonomic and phylogenetic diversity, while partially protected marine parks showed the most balanced community composition. No significant increase in fish functional diversity was found in the protected areas. Water quality, hydrological condition, and protection level were the primary factors affecting community variation for taxonomic, functional, and phylogenetic diversity, respectively. Fish species composition significantly varied with different protection levels, and species turnover was the main component of the dissimilarity. Future management of marine protected areas should assess multifaceted biological indicators and establish a rational conservation scheme.

The multiple-mechanisms hypothesis of biodiversity–stability relationships

Long-term research in grassland biodiversity experiments has provided empirical evidence that ecological and evolutionary processes are intertwined in determining both biodiversity–ecosystem functioning (BEF) and biodiversity–stability relationships. Focusing on plant diversity, we hypothesize that multifunctional stability is highest in high-diversity plant communities and that biodiversity–stability relationships increase over time due to a variety of forms of ecological complementarity including the interaction with other biota above and below ground. We introduce the multiple-mechanisms hypothesis of biodiversity–stability relationships suggesting that it is not an individual mechanism that drives long-term biodiversity effects on ecosystem functioning and stability but that several intertwined processes produce increasingly positive ecosystem effects. The following six mechanisms are important. Low-diversity plant communities accumulate more plant antagonists over time (1), and use resources less efficiently and have more open, leaky nutrient cycles (2). Conversely, high-diversity plant communities support a greater diversity and activity of beneficial interaction partners across trophic levels (3); diversify in their traits over time and space, within and across species, to optimize temporal (intra- and interannual) and spatial complementarity (4), create a more stable microclimate (5), and foster higher top-down control of aboveground and belowground herbivores by predators (6). In line with the observation that different species play unique roles in ecosystems that are dynamic and multifaceted, the particular mechanism contributing most to the higher performance and stability of diverse plant communities might differ across ecosystem functions, years, locations, and environmental change scenarios. This indicates “between-context insurance” or “across-context complementarity” of different mechanisms. We introduce examples of experiments that will be conducted to test our hypotheses and which might inspire additional work.

Endophytic and epiphytic metabarcoding reveals fungal communities on cashew phyllosphere in Kenya.

Plants intimately coexist with diverse taxonomically structured microbial communities that influence host health and productivity. The coexistence of plant microbes in the phyllosphere benefits biodiversity maintenance, ecosystem function, and community stability. However, differences in community composition and network structures of phyllosphere epiphytic and endophytic fungi are widely unknown. Using Illumina Miseq sequencing of internal transcribed spacer (ITS) and 28S rRNA gene amplicons, we characterised the epiphytic and endophytic fungal communities associated with cashew phyllosphere (leaf, flower and fruit) from Kwale, Kilifi and Lamu counties in Kenya. The ITS and 28S rRNA gene sequences were clustered into 267 and 108 operational taxonomic units (OTUs) at 97% sequence similarity for both the epiphytes and endophytes. Phylum Ascomycota was abundant followed by Basidiomycota, while class Saccharomycetes was most dominant followed by Dothideomycetes. The major non-ascomycete fungi were associated only with class Tremellales. The fungal communities detected had notable ecological functions as saprotrophs and pathotrophs in class Saccharomyectes and Dothideomycetes. The community composition of epiphytic and endophytic fungi significantly differed between the phyllosphere organs which was statistically confirmed by the Analysis of Similarity test (ANOSIM Statistic R: 0.3273, for 28S rRNA gene and ANOSIM Statistic R: 0.3034 for ITS). The network analysis revealed that epiphytic and endophytic structures were more specialized, modular and had less connectance. Our results comprehensively describe the phyllosphere cashew-associated fungal community and serve as a foundation for understanding the host-specific microbial community structures among cashew trees.

Tree species diversity drives the land surface phenology of seasonally dry tropical woodlands

Abstract Seasonal foliage display (leaf phenology) is a key determinant of ecosystem function. Variation in land surface phenology, observed via space‐borne remote sensing, can be explained at broad spatial scales by climate, but we lack understanding of how vegetation structure and floristic diversity mediates these relationships. This lack of understanding hampers our ability to predict changes in phenology and therefore ecosystem function, in light of rapid ongoing shifts in biodiversity and ecosystem structure due to land use and climate change. We combined a network of 619 vegetation monitoring sites across seasonally dry tropical deciduous woodlands in Zambia with land surface phenology metrics to investigate the role of tree species diversity, composition and vegetation structure on patterns of land surface phenology, including the phenomenon of pre‐rain green‐up. Tree species diversity was associated with earlier pre‐rain green‐up, a longer growing season, and greater cumulative foliage production. Independent of diversity, proportional abundance of Detarioideae species (subfamily of Fabaceae) was associated with a longer growing season by facilitating earlier pre‐rain green‐up. Woodland stands with larger trees green up earlier, suggesting access to deep groundwater reserves. Senescence metrics showed variation among sites but were not well‐explained by precipitation, temperature, structure or diversity. Synthesis: Tree diversity, composition and structure are co‐determinants of seasonal patterns of foliage display in seasonally dry tropical deciduous woodlands, as measured via land surface phenology, at regional scale. Our study identifies both a niche complementarity effect whereby diverse woodlands exhibit longer growing seasons, as well as a mass‐ratio effect whereby detarioid species drive earlier pre‐rain green‐up, providing insights into the mechanisms underlying the biodiversity ecosystem function relationship in this biome. We stress the importance of considering biotic controls on ecosystem functioning in the next generation of earth‐system models predicting the response of communities to global change.

Secondary production and biomass in mussel assemblages relate to species richness and stream size but not life history

AbstractIncreases in species richness with habitat area (species–area relationship, or SAR) and increases in ecosystem function with species richness (biodiversity–ecosystem functioning, or BEF) are widely studied ecological patterns. Incorporating functional trait analysis into assemblage datasets may help clarify interpretations of SAR and BEF relationships in natural ecological systems. For example, life history theory can be used to make predictions about what species are most important in generating ecosystem function given a certain set of environmental conditions. We used quantitative assemblage data for freshwater mussels at nine sites in western Alabama, USA, to test for SAR and BEF relationships. At each site, we calculated species richness, mussel assemblage density, and two fundamental metrics of ecosystem function: biomass and secondary production. We also tested whether the proportional biomass and production contributions from species belonging to each of three life history strategies—opportunistic strategists adapted to unstable or frequently disturbed habitats, periodic strategists adapted to habitats subject to predictable large‐scale disturbances, and equilibrium strategists adapted to stable habitats—varied longitudinally with stream drainage area, a proxy for habitat area. Species richness increased with stream size (SAR), and both biomass and production increased with species richness (BEF) and mussel density. There were few longitudinal changes in the proportional contributions of the different life history strategy classifications that we used, but the invasive clam Corbicula fluminea contributed proportionally more biomass and production at sites that had smaller drainage areas. This study provides further evidence for a clear longitudinal SAR in stream‐dwelling taxa. It also suggests BEF relationships for biomass and secondary production in natural assemblages but underscores the importance of assemblage density in BEF studies that use observational field data. Variation in proportional biomass and production contributions by different life history strategies was likely limited by the size of the stream size gradient in our study, as contributions were uniformly high for species with life history traits better adapted to stable and productive habitats such as mid‐sized rivers with low or predictable hydrologic disturbance frequencies. This highlights the need to understand how organisms' functional traits govern their relationships to the environment at different scales.

Plant diversity decreases greenhouse gas emissions by increasing soil and plant carbon storage in terrestrial ecosystems.

The decline in global plant diversity has raised concerns about its implications for carbon fixation and global greenhouse gas emissions (GGE), including carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). Therefore, we conducted a comprehensive meta-analysis of 2103 paired observations, examining GGE, soil organic carbon (SOC) and plant carbon in plant mixtures and monocultures. Our findings indicate that plant mixtures decrease soil N2O emissions by 21.4% compared to monocultures. No significant differences occurred between mixtures and monocultures for soil CO2 emissions, CH4 emissions or CH4 uptake. Plant mixtures exhibit higher SOC and plant carbon storage than monocultures. After 10 years of vegetation development, a 40% reduction in species richness decreases SOC content and plant carbon storage by 12.3% and 58.7% respectively. These findings offer insights into the intricate connections between plant diversity, soil and plant carbon storage and GGE-a critical but previously unexamined aspect of biodiversity-ecosystem functioning.

Sustainable nature‐based solutions require establishment and maintenance of keystone plant‐pollinator interactions

Abstract Many nature‐based solutions (NBS), including urban greenspaces, urban agriculture and agroforestry, depend upon animal‐pollinated plants to sequester carbon or to provide other ecosystem services. Thus, long‐term success of these solutions also depends upon resilient pollinator communities. Despite their importance to functioning communities, a literature search revealed that 0%–3% of papers on NBS and related topics considered pollinators or pollination. Pollinators were more likely to be considered in the subgroup of papers on NBS related to agricultural production, where 12.5% considered pollination. Conservation of species interactions is essential to conservation of biodiversity and the sustained benefits of NBS. By applying our understanding of the ecology of plant‐pollinator mutualisms to the implementation of NBS, we can promote their functioning under future climatic conditions. In particular, we point to the need to identify keystone plants and pollinators, those species that contribute most to biodiversity maintenance, community stability and ecosystem function, and to leverage these species and their interactions in NBS and conservation efforts. We further advocate for the use of phylogenetic trait‐based analyses to understand the characteristics associated with keystoneness. Synthesis: Resilience of pollination services rests upon the responses of keystone species and their partners, and the likelihood that they continue to express traits that confer mutual benefit under future climates. By understanding the traits of species of outsized importance to their communities, we gain insight into the mechanisms underlying the resilience of pollination services and the NBS that rely on those services in a changing world.

Mixed forests provide higher levels of growth and yield than monocultures across a broad range of conditions

Compared with single-species forests, mixed forests tend to provide more forest ecosystem functions and services. However, there is a lack of detailed understanding of the basic mechanisms of the impact of species diversity on tree growth and forest productivity. The main drivers of this relationship are also still under discussion. Here, we synthesized information from 93 studies to quantify the increase in tree size, crown size and stand productivity in mixed stands, and conducted a meta-analysis on the response of tree growth and forest productivity to species mixing. Tree size, crown size and stand productivity increased by 7.4 % (2.4–12.5 %), 12.6 % (5.6–20.1 %), and 33.0 % (18.7–49.0 %), respectively, in mixed stands compared with single-species stands. Our results show that when all observations are included, the mean effect sizes of tree size, crown size, and stand productivity were greater than when only the equal stand density observations were included. Stand age and stand density were the most important moderators affecting tree size in mixed forests. Stand age, shade tolerance and soil acidity were the most important moderators influencing the effect sizes of crown size, and shade tolerance was the most important moderator influencing the effect sizes of stand productivity. We found that these positive mixing effects were also modulated by tree functional traits, stand characteristics, and climatic conditions. For different growth variables, the moderators that affect their growth in the mixed forests were different. Therefore, in the afforestation practices for differing management objectives, foresters should give priority to the factors that have the most important impact on them to achieve their goals. Our results have implications for linking biodiversity-ecosystem functioning relationships and forest management practices and may aid the development of more appropriate afforestation strategies.

Tree species richness improves soil net nitrogen mineralization rates in a young biodiversity-ecosystem function experiment

Forest ecosystems are facing declining plant species diversity. However, the effects of reduced tree species diversity on soil nutrient supply and tree productivity remain poorly understood. We conducted a biodiversity-ecosystem function experiment with a range of subtropical tree species richness (1, 4, 8, 16, and 32) to investigate the impacts of tree species diversity on soil net nitrogen (N) mineralization rates and its regulation on tree productivity in a young subtropical forest experiment. Our findings indicate a log-linear trend between soil net N mineralization rates and tree species richness, potentially suggesting an improvement in soil N supply capacity with greater species richness. Leaf N content, soil water content and peroxidase enzyme activity were identified as primary positive predictors influencing soil net N mineralization rates. In monoculture forests, soil net N mineralization rates were negatively correlated with litter production and tree basal area, while no such correlation was observed in mixed forests. This implies that soil net N mineralization rates play a critical role in tree productivity for monoculture forests. Together, these results provide strong evidence that the rate of decrease in soil nutrient supply capacity potential accelerates with the loss of tree species diversity in young tree communities, and highlights the importance of increasing tree species diversity to mitigate nutrient limitations. Therefore, preserving tree species diversity is crucial for the future functionality of ecosystems amidst global biodiversity loss.

Rubble persistence under ocean acidification threatened by accelerated bioerosion and lower-density coral skeletons.

As the balance between erosional and constructive processes on coral reefs tilts in favor of framework loss under human-induced local and global change, many reef habitats worldwide degrade and flatten. The resultant generation of coral rubble and the beds they form can have lasting effects on reef communities and structural complexity, threatening the continuity of reef ecological functions and the services they provide. To comprehensively capture changing framework processes and predict their evolution in the context of climate change, heavily colonized rubble fragments were exposed to ocean acidification (OA) conditions for 55 days. Controlled diurnal pH oscillations were incorporated in the treatments to account for the known impact of diel carbonate chemistry fluctuations on calcification and dissolution response to OA. Scenarios included contemporary pH (8.05 ± 0.025 diel fluctuation), elevated OA (7.90 ± 0.025), and high OA (7.70 ± 0.025). We used a multifaceted approach, combining chemical flux analyses, mass alteration measurements, and computed tomography scanning images to measure total and chemical bioerosion, as well as chemically driven secondary calcification. Rates of net carbonate loss measured in the contemporary conditions (1.36 kg m-2 year-1) were high compared to literature and increased in OA scenarios (elevated: 1.84 kg m-2 year-1 and high: 1.59 kg m-2 year-1). The acceleration of these rates was driven by enhanced chemical dissolution and reduced secondary calcification. Further analysis revealed that the extent of these changes was contingent on the density of the coral skeleton, in which the micro- and macroborer communities reside. Findings indicated that increased mechanical bioerosion rates occurred in rubble with lower skeletal density, which is of note considering that corals form lower-density skeletons under OA. These direct and indirect effects of OA on chemical and mechanical framework-altering processes will influence the permanence of this crucial habitat, carrying implications for biodiversity and reef ecosystem function.

Ecosystem functioning during biodiversity loss and recovery

Anthropogenic biodiversity loss can impair ecosystem functioning. Human activities are often managed with the aim of reversing biodiversity loss and its associated functional impacts. However, it is currently unknown whether biodiversity–ecosystem function (BEF) relationships observed during biodiversity recovery are the same as those observed during biodiversity loss. This will depend on how species extirpation and recolonisation sequences compare and how different species influence ecosystem functioning. Using data from a marine benthic invertebrate community, we modelled how bioturbation potential – a proxy for benthic ecosystem functioning – changes along biodiversity loss and recovery sequences governed by species' sensitivity to physical disturbance and recolonisation capability, respectively. BEF relationships for biodiversity loss and recovery were largely the same despite species extirpation and recolonisation sequences being different. This held true irrespective of whether populations were assumed to exhibit compensatory responses as species were removed or added. These findings suggest that the functional consequences of local biodiversity loss can be reversed by alleviating its drivers, as different species present at comparable levels of species richness during biodiversity loss and recovery phases have similar functional effects. Empirically verifying and determining the generality of our model‐based results are potential next steps for future research.

Integrating different facets of diversity into food web models: how adaptation among and within functional groups shape ecosystem functioning

Adaptation of communities to environmental fluctuations can emerge from different facets of biodiversity, which may impact ecosystem functioning differently. Previous work in the field of biodiversity–ecosystem functioning (BEF) examined how ecosystem functions can be influenced by two sources of adaptive potential: sorting – i.e. changes in community composition due to fitness differences – can occur when multiple species or groups are present (richness), and trait adaptability – i.e. trait adjustments within species or functional groups – can emerge from genetic or phenotypic diversity. However, their effect is typically studied separately, and often in the context of only one trophic level. Therefore, we used a trait‐based, multispecies predator–prey model to investigate how sorting and trait adaptability, at one or two trophic levels, separately or jointly shape ecosystem functions and properties, such as total biomass, production, biomass‐weighted mean trait, relative top–down control and synchrony. We found that the adaptive potential emerging from any facet of diversity induced changes in trophic interactions, in turn affecting biomass distributions within and across trophic levels, dynamical behaviour, and synchrony of biomass dynamics within a trophic level. Particularly, sorting and trait adaptability could contribute to a similar degree and at a similar time to temporal changes in ecosystem functions, but their respective contribution depended on the speed of trait adaptation, the trait range between similar functional groups and trophic interactions. We thus suggest to consider multiple facets of diversity and their corresponding sources of adaptive potential to deepen our mechanistic understanding of BEF relationships, especially in the context of rapid biodiversity change.

Which aspect of functional diversity shapes ecosystem functioning in exploited marine demersal fish community?

The biodiversity-ecosystem functioning (BEF) relationship is a critical topic in ecological research, as it guides the maintenance of ecosystem functioning in the face of climate change and human disturbance. However, the BEF relationship is complicated by the fact that biodiversity has multiple dimensions, and in particular functional diversity may be strongly correlated with community productivity. But the understanding is still lacking about how different functional traits determine community productivity. The present study tested the relationship between biodiversity and community productivity empirically in a demersal fish community, based on continuous bottom trawl surveys in Haizhou Bay, China from 2013 to 2022. Structural equation modeling (SEM) with composite variables was used to evaluate the relationships among environmental factors, species diversity (SD), functional diversity (FD), community weighted mean traits (CWM), and community productivity (CP), and the roles of different aspects of functional traits were further compared. The results showed that there were considerable heterogeneities in the temporal and spatial distributions of CP, and PCA revealed that the CP was weakly correlated with both species and functional diversity. SEM showed that CWM had the greatest influences on CP (r = 0.63), followed by SD (r = 0.52), and FD had the least impact (r = -0.42). This finding supported the mass ratio hypothesis, indicating that functional traits of dominant species determined community productivity. Environmental factors showed no direct impacts on CP but had indirect effects through biodiversity. Regarding the role of different functional traits, the trait of locomotion was the most important driver of CP in terms of CWM, while the food acquisition was more important than other components in terms of FD. Our study can contribute to an improved comprehension of the BEF linkages in marine fish communities, and serve as a guideline for fisheries management and biodiversity protection in the face of climate changes.