Across species‐pool aggregation alters grassland productivity and diversity

Plant performance is determined by the balance of intra‐ and interspecific neighbors within an individual's zone of influence. If individuals interact over smaller scales than the scales at which communities are measured, then altering neighborhood interactions may fundamentally affect community responses. These interactions can be altered by changing the number (species richness), abundances (species evenness), and positions (species pattern) of the resident plant species, and we aimed to test whether aggregating species at planting would alter effects of species richness and evenness on biomass production at a common scale of observation in grasslands. We varied plant species richness (2, 4, or 8 species and monocultures), evenness (0.64, 0.8, or 1.0), and pattern (planted randomly or aggregated in groups of four individuals) within 1 × 1 m plots established with transplants from a pool of 16 tallgrass prairie species and assessed plot‐scale biomass production and diversity over the first three growing seasons. As expected, more species‐rich plots produced more biomass by the end of the third growing season, an effect associated with a shift from selection to complementarity effects over time. Aggregating conspecifics at a 0.25‐m scale marginally reduced biomass production across all treatments and increased diversity in the most even plots, but did not alter biodiversity effects or richness–productivity relationships. Results support the hypothesis that fine‐scale species aggregation affects diversity by promoting species coexistence in this system. However, results indicate that inherent changes in species neighborhood relationships along grassland diversity gradients may only minimally affect community (meter) – scale responses among similarly designed biodiversity–ecosystem function studies. Given that species varied in their responses to local aggregation, it may be possible to use such species‐specific results to spatially design larger‐scale grassland communities to achieve desired diversity and productivity responses.     

Is community persistence related to diversity? A test with prairie species in a long-term experiment

Community persistence, or the ability of a community to maintain species composition and diversity through time, is a component of stability that is important to restoration. We ran a biodiversity–ecosystem functioning experiment for three years, and then stopped weeding it for 5–6 years, which allowed us to test whether increased plant species diversity and dissimilarity in height would lead to increased community persistence in the face of high invasion pressure by non-native species. Our approach was unique in that the experiment varied richness (one or four species) and evenness (three levels plus monocultures of the dominant species) using two separate dissimilarity types (having all tall species or having tall and short species combined) in six spatiotemporal blocks. Persistence was quantified as to how well positive productivity–diversity relationships, proportion of planted native species, and species richness remained unchanged over time. Thus, high persistence values indicate low levels of invasion and local extinction. We found that the positive relationship between diversity measures and productivity persisted after cessation of weeding. The proportion of planted species was 32% higher in mixture than in monoculture plots, indicating that monocultures were more heavily invaded by non-native species. Reduced evenness did not affect persistence measures in plots with dissimilar heights, but measures declined linearly with decreased evenness in plots with all tall species. Our results suggest that (1) persistence–diversity relationships are likely to vary with the traits of species becoming rare and going extinct, and (2) it is important to restore higher species diversity in restoration projects to favor the long-term persistence of planted species.     

The relationship between productivity and multiple aspects of biodiversity in six grassland communities

Biodiversity is a multifaceted concept but most studies examining the association between the biodiversity of a community and its productivity focus only on species richness. Consequently, studies are needed to examine how other facets of biodiversity vary with productivity if we want to have a better understanding of the distribution of biodiversity across our planet. We evaluated how a number of biodiversity measures (species richness, evenness, dominance, rarity, Simpson’s diversity, and Shannon–Weiner diversity) varied across natural productivity gradients at 6 grassland sites in the continental US. Variation in productivity did not account for a substantial amount of variation in any measure of biodiversity at small spatial scales (≈1 m²) at most sites. When productivity accounted for substantial variation in biodiversity, different measures of biodiversity responded to productivity in different ways. For example, dominance changed in a U-shaped fashion along a productivity gradient whereas richness increased in an asymptotic fashion. Consequently, diversity indices, which account for both species richness and evenness, varied in a hump-shaped fashion along the productivity gradient. Our results highlight that an exclusive focus on the association between species richness and productivity provides an incomplete picture of how a community’s biodiversity is related to its functioning.     

广西马尾松林植物功能多样性与生产力的关系

探索植物多样性与生产力的关系可为森林经营与管理提供科学基础。本研究以广西4个地区的马尾松(Pinus massoniana)人工林群落为研究对象, 通过计算物种多样性、功能多样性和功能优势值, 运用相关分析、自动线性建模和方差划分等方法, 分析了多样性与生产力的关系。研究发现, 生产力与物种丰富度、Shannon指数、功能丰富度、功能均匀度极显著正相关(P < 0.01), 与物种均匀度、功能多样性、功能离散度、功能团个数、坡向显著正相关(P < 0.05), 与林龄极显著负相关(P < 0.01), 4个功能多样性参数和4个物种多样性参数两两之间皆为显著正相关; 未发现初始生物量制约生产力的提高; 方差划分最优模型中, 功能多样性参数效应、功能优势值效应和林龄效应分别解释生产力方差的56%、43%和33%, 功能多样性参数效应和功能优势值效应重叠部分高达27%; 生态位互补效应主要由功能丰富度和功能均匀度产生, 选择效应主要由生长型优势值产生; 生长型优势值为灌木的样地生产力较高, 次优种或过渡种对生态系统功能也有重要作用。以生产力为响应变量的自动线性建模最佳子集包括重要性由大到小的5个因素: 林龄、生长型优势值、功能丰富度、功能均匀度、功能团个数。建议维护森林功能多样性, 加强林下叶层植物保护, 用好功能重要的物种, 通过林下叶层的补偿性光合作用和生长竞争, 有效地提高生产力和生物多样性。     

Temporal stability in forest productivity increases with tree diversity due to asynchrony in species dynamics

Theory predicts a positive relationship between biodiversity and stability in ecosystem properties, while diversity is expected to have a negative impact on stability at the species level. We used virtual experiments based on a dynamic simulation model to test for the diversity–stability relationship and its underlying mechanisms in Central European forests. First our results show that variability in productivity between stands differing in species composition decreases as species richness and functional diversity increase. Second we show temporal stability increases with increasing diversity due to compensatory dynamics across species, supporting the biodiversity insurance hypothesis. We demonstrate that this pattern is mainly driven by the asynchrony of species responses to small disturbances rather than to environmental fluctuations, and is only weakly affected by the net biodiversity effect on productivity. Furthermore, our results suggest that compensatory dynamics between species may enhance ecosystem stability through an optimisation of canopy occupancy by coexisting species.     

Biodiversity Increases the Productivity and Stability of Phytoplankton Communities

Global biodiversity losses provide an immediate impetus to elucidate the relationships between biodiversity, productivity and stability. In this study, we quantified the effects of species richness and species combination on the productivity and stability of phytoplankton communities subject to predation by a single rotifer species. We also tested one mechanism of the insurance hypothesis: whether large, slow-growing, potentially-defended cells would compensate for the loss of small, fast-growing, poorly-defended cells after predation. There were significant effects of species richness and species combination on the productivity, relative yield, and stability of phytoplankton cultures, but the relative importance of species richness and combination varied with the response variables. Species combination drove patterns of productivity, whereas species richness was more important for stability. Polycultures containing the most productive single species, Dunaliella, were consistently the most productive. Yet, the most species rich cultures were the most stable, having low temporal variability in measures of biomass. Polycultures recovered from short-term negative grazing effects, but this recovery was not due to the compensation of large, slow-growing cells for the loss of small, fast-growing cells. Instead, polyculture recovery was the result of reduced rotifer grazing rates and persisting small species within the polycultures. Therefore, although an insurance effect in polycultures was found, this effect was indirect and unrelated to grazing tolerance. We hypothesize that diverse phytoplankton assemblages interfered with efficient rotifer grazing and that this “interference effect” facilitated the recovery of the most productive species, Dunaliella. In summary, we demonstrate that both species composition and species richness are important in driving patterns of productivity and stability, respectively, and that stability in biodiverse communities can result from an alteration in consumer functioning. Our findings underscore the importance of predator-prey dynamics in determining the relationships between biodiversity, productivity and stability in producer communities.     

Biodiversity–productivity relationship in ponds: Community and metacommunity patterns along time and environmental gradients

Primary production correlates with diversity in various ways. These patterns may result from the interaction of various mechanisms related to the environmental context and the spatial and temporal scale of analysis. However, empirical evidence on diversity‐productivity patterns typically considers single temporal and spatial scales, and does not include the effect of environmental variables. In a metacommunity of macrophytes in ephemeral ponds, we analysed the diversity‐productivity relationship patterns in the field, the importance of the environmental variables of pond size and heterogeneity on such relationship, and the variation of these patterns at local (community level) and landscape scales (metacommunity level) across 52 ponds on twelve occasions, over five years (2005–2009). Combining all sampling dates, there were 377 ponds and 1954 sample‐unit observations. Vegetation biomass was used as a proxy for productivity, and biodiversity was represented by species richness, evenness, and their interaction. Environmental variables comprised pond area, depth and internal heterogeneity. Productivity and species richness were not directly related at the metacommunity level, and were positively related at the community level. Taking environmental variables into account revealed positive species richness‐productivity relationships at the metacommunity level and positive quadratic relationships at the community level. Productivity showed both positive and negative linear and nonlinear relationships with the size and heterogeneity of ponds. We found a weak relationship between productivity and evenness. The identity of variables associated with productivity changed between spatial scales and through time. The pattern of relationships between productivity and diversity depends on spatial scale and environmental context, and changes idiosyncratically through time within the same ecosystem. Thus, the diversity‐productivity relationship is not only a property of the study system, but also a consequence of environmental variations and the temporal and spatial scale of analysis.     

浙江定海次生林内物种丰富度与生物量和生产力关系的环境依赖性

迄今生物多样性与生态系统功能关系的研究主要在物种组成随机配置的人工生态系统中进行, 在自然生态系统中研究较少, 且未考虑环境因子如何影响生态系统功能及其与生物多样性的关系。本研究选取亚热带广泛分布的次生林为研究对象, 利用模型拟合的方法, 探讨亚热带次生林中物种丰富度与生物量和生产力之间的关系, 以及环境因子(海拔、坡度、坡向、土层厚度)和次生林恢复时间(林龄)对生物量、生产力、物种丰富度与生物量和生产力间关系的影响。结果表明, 当不考虑环境因子时, 物种丰富度与生物量之间存在显著的线性正相关关系, 而与生产力之间存在显著的二次关系(先增加后减少的驼峰型)。当考虑环境因子时, 个体密度和土层厚度对生物量具有显著影响, 而环境因子对生产力并无显著效应。在坡度较陡、坡向朝南及土层较厚的环境条件下, 物种丰富度与生物量具有显著的线性正相关关系; 而在坡度较缓、坡向朝北及土层较薄的环境条件下, 物种丰富度不影响生物量。在较高海拔环境条件下, 生产力随物种丰富度先增加后减少(驼峰形状), 而在其他环境条件下, 生产力均不响应物种丰富度。以上结果说明自然森林生态系统中物种丰富度与生物量和生产力的关系存在差异, 且其相互间的关系依赖于环境因子。     

Drivers of productivity and its temporal stability in a tropical tree diversity experiment

There is increasing evidence that mixed‐species forests can provide multiple ecosystem services at a higher level than their monospecific counterparts. However, most studies concerning tree diversity and ecosystem functioning relationships use data from forest inventories (under noncontrolled conditions) or from very young plantation experiments. Here, we investigated temporal dynamics of diversity–productivity relationships and diversity–stability relationships in the oldest tropical tree diversity experiment. Sardinilla was established in Panama in 2001, with 22 plots that form a gradient in native tree species richness of one‐, two‐, three‐ and five‐species communities. Using annual data describing tree diameters and heights, we calculated basal area increment as the proxy of tree productivity. We combined tree neighbourhood‐ and community‐level analyses and tested the effects of both species diversity and structural diversity on productivity and its temporal stability. General patterns were consistent across both scales indicating that tree–tree interactions in neighbourhoods drive observed diversity effects. From 2006 to 2016, mean overyielding (higher productivity in mixtures than in monocultures) was 25%–30% in two‐ and three‐species mixtures and 50% in five‐species stands. Tree neighbourhood diversity enhanced community productivity but the effect of species diversity was stronger and increased over time, whereas the effect of structural diversity declined. Temporal stability of community productivity increased with species diversity via two principle mechanisms: asynchronous responses of species to environmental variability and overyielding. Overyielding in mixtures was highest during a strong El Niño‐related drought. Overall, positive diversity–productivity and diversity–stability relationships predominated, with the highest productivity and stability at the highest levels of diversity. These results provide new insights into mixing effects in diverse, tropical plantations and highlight the importance of analyses of temporal dynamics for our understanding of the complex relationships between diversity, productivity and stability. Under climate change, mixed‐species forests may provide both high levels and high stability of production.     

Biodiversity and tallgrass prairie decomposition: the relative importance of species identity, evenness, richness, and micro-topography

Biodiversity has been declining in many areas, and there is great interest in determining whether this decline affects ecosystem functioning. Most biodiversity—ecosystem functioning studies have focused on the effects of species richness on net primary productivity. However, biodiversity encompasses both species richness and evenness, ecosystem functioning includes other important processes such as decomposition, and the effects of richness on ecosystem functioning may change at different levels of evenness. Here, we present two experiments on the effects of litter species evenness and richness on litter decomposition. In the first experiment, we varied the species evenness (three levels), identity of the dominant species (three species), and micro-topographic position (low points [gilgais] or high points between gilgais) of litter in three-species mixtures in a prairie in Texas, USA. In a second experiment, we varied the species evenness (three levels), richness (one, two, or four species per bag), and composition (random draws) of litter in a prairie in Iowa, USA. Greater species evenness significantly increased decomposition, but this effect was dependent on the environmental context. Higher evenness increased decomposition rates only under conditions of higher water availability (in gilgais in the first experiment) or during the earliest stages of decomposition (second experiment). Species richness had no significant effect on decomposition, nor did it interact with evenness. Micro-topographic position and species identity and composition had larger effects on decomposition than species evenness. These results suggest that the effects of litter species diversity on decomposition are more likely to be manifested through the evenness component of diversity than the richness component, and that diversity effects are likely to be environmentally context dependent.     

Global macroecology of bird assemblages in urbanized and semi‐natural ecosystems

Aim Despite the increasing pace of urbanization, little is known about how this process affects biodiversity globally. We investigate macroecological patterns of bird assemblages in urbanized areas relative to semi‐natural ecosystems. Location World‐wide. Methods We use a database of quantitative bird surveys to compare key assemblage structure parameters for plots in urbanized and semi‐natural ecosystems controlling for spatial autocorrelation and survey methodology. We use the term ‘urbanized’ instead of ‘urban’ ecosystems as many of the plots were not located in the centre of towns but in remnant habitat patches within conurbations. Results Some macroecological relationships were conserved in urbanized landscapes. Species–area, species–abundance and species–biomass relationships did not differ significantly between urbanized and non‐urbanized environments. However, there were differences in the relationships between productivity and assemblage structure. In forests, species richness increased with productivity; in both forests and open habitats, the evenness of species abundances declined as productivity increased. Among urbanized plots, instead, both species richness and the evenness of species abundances were independent of variation in productivity. Main conclusions Remnant habitats within urbanized areas are subject to many ecological alterations, yet key macroecological patterns differ remarkably little in urbanized versus non‐urbanized plots. Our results support the need for increased conservation activities in urbanized landscapes, particularly given the additional benefits of local experiences of biodiversity for the human population. With increasing urbanization world‐wide, broad‐scale efforts are needed to understand and manage the effects of this driver of change on biodiversity.     

Plant functional traits improve diversity‐based predictions of temporal stability of grassland productivity

Synthesis The temporal stability of plant production is greater in communities with high than low species richness, but stability also may depend on species abundances and growth‐related traits. Annual precipitation varied by greater than a factor of three over 11 years in central Texas, USA leading to large variation in production. Stability was greatest in communities that were not dominated by few species and in which dominant species rooted shallowly, had dense leaves, or responded to the wettest year with a minimal increase in production. Stability may depend as much on species abundances and functional traits as on species richness alone. Aboveground net primary productivity (ANPP) varies in response to temporal fluctuations in weather. Temporal stability of community ANPP may be increased by increasing plant species richness, but stability often varies at a given richness level implying a dependence on abundances and functional properties of member species. We measured stability in ANPP during 11 years in field plots (Texas, USA) in which we varied the richness and relative abundances of perennial grassland species at planting. We sought to identify species abundance patterns and functional traits linked to the acquisition and processing of essential resources that could be used to improve richness‐based predictions of community stability. We postulated that community stability would correlate with abundance‐weighted indices of traits that influence plant responses to environmental variation. Annual precipitation varied by a factor of three leading to large inter‐annual variation in ANPP. Regression functions with planted and realized richness (species with > 1% of community ANPP during the final four years) explained 32% and 25% of the variance in stability, respectively. Regression models that included richness plus the fraction of community ANPP produced by the two most abundant species in combination with abundance‐weighted values of either the fraction of sampled root biomass at 20–45 cm depth, leaf dry matter content (LDMC), or response to greater‐than‐average precipitation of plants grown in monocultures explained 58–69% (planted richness) and 58–64% (realized richness) of the variance in stability. Stability was greatest in communities that were not strongly dominated by only two species and in which plants rooted shallowly, had high values of LDMC, or responded to the wettest year with a minimal increase in ANPP. Our results indicate that the temporal stability of grassland ANPP may depend as much on species abundances and functional traits linked to plant responses to precipitation variability as on species richness alone.     

Resource stoichiometry and consumers control the biodiversity-productivity relationship in pelagic metacommunities

Recent theory suggests that both biodiversity and productivity are constrained by resource supply rates and ratios and that resource stoichiometry is the key to understanding the relationship between biodiversity and productivity. We experimentally tested this theory using pelagic metacommunities. We amended existing predictions by explicitly considering evenness as an aspect of biodiversity and including control of algal biomass by consumption in addition to competition. The metacommunities received a different phosphorus (P) supply and the three patches within each metacommunity differed in their nitrogen (N) supply, which created different N∶P ratios (2, 16, and 128). All patches were inoculated with a phytoplankton assemblage consisting of five species, and half of the metacommunities received two ciliate species as consumers. At the level of the entire metacommunity, algal biomass increased with increasing P supply, whereas species richness and evenness decreased with increasing P supply. Without consumers, resource use efficiency (RUE; realized biomass per unit of P) increased with increasing richness and evenness. Consumer presence reduced overall biomass and richness and precluded a correlation between RUE and biodiversity. At the patch level, local evenness correlated with higher RUE at both imbalanced N∶P ratios (2 and 128) but not at a balanced N∶P ratio. In conclusion, overall P supply constrained realized biomass and altered diversity, whereas resource stoichiometry shaped the relationship between biodiversity and RUE.     

Predicting productivity in tropical reservoirs: The roles of phytoplankton taxonomic and functional diversity

Primary productivity is intimately linked with biodiversity and ecosystem functioning. Much of what is known today about such relationship has been based on the manipulation of species richness. Other facets of biodiversity, such as functional diversity, have been neglected within this framework, particularly in freshwater systems. We assess the adequacy of different diversity measures, from species richness and evenness, to functional groups richness and functional diversity indices, to predict primary productivity in 19 tropical reservoirs of central Brazil, built to generate hydroelectric energy. We applied linear mixed models (and model selection based on the Akaike’s information criterion) to achieve our goal, using chlorophyll-a concentration as a surrogate for primary productivity. A total of 412 species were collected in this study. Overall we found a positive relation between productivity and diversity, with functional evenness representing the only exception. The most parsimonious models never included functional group classifications, with at least one continuous measure of functional diversity being present in many models. The best model included only species richness and explained 24.1% of variability in productivity. We therefore advise the use of species richness as an indicator of productivity in tropical freshwater environments. However, since the productivity–diversity relationship is known to be scale dependent, we recommend the use of continuous measures of functional diversity in future biodiversity and ecosystem functioning studies, in order to be certain that all functional differences between communities are being accounted for.     

高寒草甸植物群落中相似性、物种多样性与地上生物量的年际变异性

相似性似说通过物种构成的相似性来解释物种丧失是如何影响生物量的变异性的,但还没有得到检验。本研究通过设置在青藏高原东部地区的高寒草甸植物群落中的74个永久样方．采集3年(1999～2001)植物生长高峰期的群落数据,试图检验物种构成的相似性是如何解释物种多样性对地上生物量年际变异性的影响。结果表明：随着物种丰富度增加,生物量变异性降低;而随着均匀度的增加,生物量的变异性尽管在均匀度中等程度时似乎保持在同一水平,但总体上呈下降趋势;物种构成上的相似性解释了地上生物量变异性的大部分,而且随着物种构成上的相似性的增加,生物量的变异性降低;物种丰富度和均匀度均与物种构成上的相似性没有显著相关关系。这些结果表明：尽管生物多样性的丧失可能不必导致物种丰富群落中物种构成上的相似性,但相似性与地上生物量的变异性的因果联系可能是稳健的．由于本研究是在自然群落中进行的,对物种构成的相似性没有进行直接控制,因此,要深入理解相似性是如何影响生物多样性对生态系统功能变异性的效应的机制,可能还需要直接对物种构成的相似性进行控制的实验研究。     

Biodiversity, productivity and stability in real food webs

The global biodiversity crisis has motivated new theory and experiments that explore relationships between biodiversity (species richness and composition in particular), productivity and stability. Here we emphasize that these relationships are often bi-directional, such that changes in biodiversity can be both a cause and a consequence of changes in productivity and stability. We hypothesize that this bi-directionality creates feedback loops, as well as indirect effects, that influence the complex responses of communities to biodiversity losses. Important, but often neglected, mediators of this complexity are trophic interactions. Recent work shows that consumers can modify, dampen or even reverse the directionality of biodiversity-productivity-stability linkages inferred from the plant level alone. Such consumer mediation is likely to be common in many ecosystems. We suggest that merging biodiversity research and food-web theory is an exciting and pressing frontier for ecology, with implications for biodiversity conservation.     

Species evenness and invasion resistance of experimental grassland communities

Concern for biodiversity loss coupled with the accelerated rate of biological invasions has provoked much interest in assessing how native plant species diversity affects invasibility. Although experimental studies extensively document the effects of species richness on invader performance, the role of species evenness in such studies is rarely examined. Species evenness warrants more attention because the relative abundances of species can account for substantially more of the variance in plant community diversity and tend to change more rapidly and more frequently in response to disturbances than the absolute numbers of species. In this study, we experimentally manipulated species evenness within native prairie grassland mesocosms. We assessed how evenness affected primary productivity, light availability and the resistance of native communities to invasion. The primary productivity of native communities increased significantly with species evenness, and this increase in productivity was accompanied by significant decreases in light availability. However, evenness had no effect on native community resistance to invasion by three common exotic invasive species. In this study, niche complementarity provides a potential mechanism for the effects of evenness on productivity and light availability, but these effects apparently were not strong enough to alter the invasibility of the experimental communities. Our results suggest that species evenness enhances community productivity but provides no benefit to invasion resistance in otherwise functionally diverse communities.     

Effect of phytoplankton size diversity on primary productivity in the North Pacific: trait distributions under environmental variability

While most biodiversity and ecosystem functioning (BEF) studies have found positive effects of species richness on productivity, it remain unclear whether similar patterns hold for marine phytoplankton with high local richness. We use the continuous trait‐based modelling approach, which assumes infinite richness and represents diversity in terms of the variance of the size distribution, to investigate the effects of phytoplankton size diversity on productivity in a three‐dimensional ocean circulation model driven by realistic physics forcing. We find a slightly negative effect of size diversity on primary production, which we attribute to several factors including functional trait‐environment interactions, flexible stoichiometry and the saturation of productivity at low diversity levels. The benefits of trait optimisation, whereby narrow size distributions enhance productivity under relatively stable conditions, tend to dominate over those of adaptive capacity, whereby greater diversity enhances the ability of the community to respond to environmental variability.     

The Influence of Historical Land Use and Water Availability on Grassland Restoration

The ecological role of historical land use has rarely been explored in the context of grassland restoration. We conducted a 4‐year field experiment in a steppe and an old field in Inner Mongolia in northern China to examine the influence of historical land use and water availability on ecosystem restoration. Species richness, evenness, and plant cover were higher in the steppe than in the old field. The steppe was more temporally stable compared with the old field in terms of species richness, evenness, plant density, and cover. Water addition increased peak aboveground biomass, belowground net primary productivity, species richness, plant density, and cover in both the steppe and the old field. Water addition also enhanced the stability of ecosystems and the restoration of grassland. Our findings suggested that historical land use determines community structure and influences the process of grassland restoration. Converting grasslands to farmland in semiarid areas can cause the long‐term loss of biodiversity and instability of ecosystem with consequent impacts on ecosystem services. The amendment of limited resources is an effective practice to increase the success of ecosystem restoration.     

Soil microbiome mediates positive plant diversity‐productivity relationships in late successional grassland species

Which processes drive the productivity benefits of biodiversity remain a critical, but unanswered question in ecology. We tested whether the soil microbiome mediates the diversity‐productivity relationships among late successional plant species. We found that productivity increased with plant richness in diverse soil communities, but not with low‐diversity mixtures of arbuscular mycorrhizal fungi or in pasteurised soils. Diversity‐interaction modelling revealed that pairwise interactions among species best explained the positive diversity‐productivity relationships, and that transgressive overyielding resulting from positive complementarity was only observed with the late successional soil microbiome, which was both the most diverse and exhibited the strongest community differentiation among plant species. We found evidence that both dilution/suppression from host‐specific pathogens and microbiome‐mediated resource partitioning contributed to positive diversity‐productivity relationships and overyielding. Our results suggest that re‐establishment of a diverse, late successional soil microbiome may be critical to the restoration of the functional benefits of plant diversity following anthropogenic disturbance.