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Extreme drought and intensification of land use pose substantial threats to ecosystem stability. However, existing studies that assess ecosystem stability focus primarily on the stability of aboveground net primary productivity (ANPP), while the stability of belowground net primary productivity (BNPP) is often not considered. Here, we examined the response patterns and drivers of ANPP stability and BNPP stability in an alpine meadow to drought and clipping (simulating grazing and mowing) by the implementation of five levels of simulated precipitation (1/12, 1/4, 1/2, 3/4 and ambient precipitation) and clipping (unclipped vs. clipped) treatments over 7 years (2016–2022). The results showed that extreme drought decreased ANPP stability, while moderate drought increased BNPP stability and net primary productivity stability. The findings highlight the importance of jointly considering above‐ and belowground processes when evaluating ecosystem stability. Moreover, clipping did not have an impact on ANPP stability but reduced BNPP stability, and clipping differentially affected the stability of ANPP and BNPP in response to extreme drought. Furthermore, ANPP stability was largely determined by species temporal asynchrony rather than richness, whereas dominant species stability strongly contributed to the variation in BNPP stability of this alpine meadow faced with drought and clipping. Synthesis: In general, these results provide experimental evidence for the decoupling of the responses of above‐ and belowground productivity stability to extreme drought and clipping. Our findings indicate that aboveground responses should not be used as the sole indicator of the whole ecosystem consequences of extreme drought and disturbance factors such as grazing or mowing, emphasizing the need to evaluate ecosystem stability from a whole ecosystem perspective. [ABSTRACT FROM AUTHOR]

A growing number of studies have demonstrated that biodiversity is a strong and positive predictor of ecosystem temporal stability by simultaneously affecting multiple underlying mechanisms of stability, that is dominance, asynchrony and averaging effects. However, to date, no study has disentangled the relative role of these key mechanisms of stability in biodiversity experiments.We created a species richness gradient by mimicking a loss of rare species and assessed the role of species richness on community stability and, more importantly, quantified the relative role of three stabilizing mechanisms, that is dominance (stabilization due to stable dominants compared to the rest of the species in the community), asynchrony (stabilization due to temporal asynchrony between species), and averaging effects (pure effect of diversity) on community stability across a species richness gradient.We found that extreme species loss negatively impacted community stability, but just three species were enough to stabilize biomass production to a level similar to highly diverse communities. However, the similar stability of communities resulted from differing contributions from each stabilizing mechanism, depending on the community diversity. Since less abundant species were more temporally variable, species loss stabilized the populations of the remaining species. The loss of rare and subordinate species reduced the dominance and averaging effects, but increased the asynchrony effect. Hence, the asynchrony effect played a major role in the stability of species poor communities, while the averaging effect drove most of the stability of species rich communities. Overall, dominance played only a minor role, accounting for 5%–15% of the stabilization, while asynchrony and averaging effects were dominating forces contributing to ~85%–95% of the total stabilization.Synthesis. This study highlights the importance of biodiversity and roles of dominant and rare species for long‐term community stability and, for the first time, disentangles relative roles of dominance effect, asynchrony and averaging effect on community stability in a real‐world biodiversity experiment. [ABSTRACT FROM AUTHOR]

The stability of ecological communities over time, often quantified using their aggregated abundance or biomass, is thought to be influenced by species richness and the asynchrony of species abundance fluctuations. However, the relationship between community stability and the stability of ecosystem functioning provided by this community has been little explored, especially for functions involving several trophic levels such as plant pollination. Understanding the mechanisms driving community stability and how this should be related to the stability of ecosystem functions is important to predict the resilience of communities in front of the increasing threats to biodiversity.Using a 5‐year dataset across 13 Mediterranean shrublands and 12 plant species, we assessed the effect of pollinator richness and asynchrony as drivers of stability in plant visitation rates and plant reproductive success. Additionally, we analysed whether the effects of species richness and visitation rate on plant reproductive success were consistent over the years.The stability of plant visitation rates is driven by the asynchrony of pollinator species abundances, but the effect of pollinator species richness is only indirect, as richer communities also tend to have more asynchronous populations. In contrast, the stability of plant reproductive success is not related to the stability of pollinator visitation rates. A year‐by‐year analysis reveals that plants in the studied system are unlikely to be limited by pollinator abundance except in specific years, blurring any potential effect of visitation rate stability on reproductive success stability.Synthesis: We highlight the importance of asynchronous fluctuating species that are redundant in their function as an important factor for the stability of ecosystems. This is particularly important for pollinators with diverse responses to environmental fluctuations, as their asynchrony between years ensures stable levels of flower visitation rates. However, we warn that final ecosystem functions such as plant reproductive success, which depends not only on pollinators but on plant competition or resource availability, might be decoupled from first order ecosystem functions (i.e. visitation rates and pollen deposition) when pollination is not a limiting factor. [ABSTRACT FROM AUTHOR]

Higher plant species diversity decreases variability of plant community productivity. The stabilizing effect of plant diversity can result from species‐specific responses to environmental fluctuations and from shifts in competitive hierarchies. Evolutionary adaptation of species to surrounding plant diversity could further decrease productivity variability.We used a three‐year dataset from a crop diversity experiment with seven species to assess the effect of crop diversity and selection history on temporal variability of yield.We found contrasting patterns of temporal variability: Yield of species varied more in mixtures than in monocultures over years. However, at community‐level, we found lower yield variability in crop mixtures compared to monocultures, although only in combination with fertilizer application under Mediterranean climate. Furthermore, we found that a mixture selection history can increase yield productivity and decrease its variability, although only in monocultures. This suggests that the interspecific interactions among crops in mixtures act as an evolutionary selective force, promoting niche complementarity.Synthesis. Our results highlight the ecological and evolutionary role of plant interactions in crop mixtures, which can affect yield stability, while also reflecting on the importance of climate and resource availability in modifying the diversity‐stability relationship. [ABSTRACT FROM AUTHOR]

The extent to which individuals experience interspecific and intraspecific interactions through their spatial arrangements within diverse plant communities, whether because of confounding effects of species richness, evenness or direct changes in species patch sizes on their neighbourhood relationships, could affect grassland biomass production and its stability at community scales. Elucidating the ways in which neighbourhood effects and species richness contribute to such community responses has important implications for how practitioners establish grasslands to meet forage production and conservation goals.We assessed the effects of altering plant species richness (3 levels: 2, 4 or 8 forage species per plot) and seed arrangements (4 levels: species mixed and seeded or seeded in 0.0625, 0.25 or 1.0 m2 single‐species patches while maintaining plot‐scale species evenness) on above‐ground biomass production and its temporal stability in developing grasslands seeded with a suite of globally common forage species (three legumes, three cool‐season grasses and two warm‐season grasses).Communities seeded with more species and those with their seeds arranged into smaller conspecific patches produced more biomass and were more temporally stable than those seeded with fewer species and larger conspecific patches. The effect of manipulating species arrangements is attributable to greater neighbourhood‐scale interspecific interactions and stronger complementary effects. Furthermore, seeding species into conspecific patches resulted in communities that were 34% more productive, that were just as temporally stable, and that had similar diversity effects as those seeded with a species mixture, as is common in grassland reconstruction efforts.Synthesis. In comparison with conventional mixed‐seeding methods, seeding grasslands with high species richness and small, single‐species patches may promote grassland reconstruction through increased biomass production, temporal stability and complementarity effects. Our study highlights the importance of regulating intraspecific interactions within diverse communities for improving grassland biomass production and suggests that efforts to re‐evaluate methods used to establish forage and conservation grasslands could result in greater biomass production and stability in these systems. [ABSTRACT FROM AUTHOR]

Abstract: A positive relationship between biodiversity and ecosystem stability has been reported in many ecosystems; however, it has yet to be determined whether and how spatial scale affects this relationship. Here, for the first time, we assessed the effects of alpha, beta and gamma diversity on ecosystem stability and the scale dependence of the slope of the diversity–stability relationship. By employing a long‐term (33 years) dataset from a temperate grassland, northern China, we calculated the all possible spatial scales with the complete combination from the basic 1‐m2 plots. Species richness was positively associated with ecosystem stability through species asynchrony and overyielding at all spatial scales (1, 2, 3, 4 and 5 m2). Both alpha and beta diversity were positively associated with gamma stability. Moreover, the slope of the diversity–area relationship was significantly higher than that of the stability–area relationship, resulting in a decline of the slope of the diversity–stability relationship with increasing area. Synthesis. With the positive species diversity effect on ecosystem stability from small to large spatial scales, our findings demonstrate the need to maintain a high biodiversity and biotic heterogeneity as insurance against the risks incurred by ecosystems in the face of global environmental changes. [ABSTRACT FROM AUTHOR]

There is increasing evidence that species diversity enhances the temporal stability (TS) of community productivity in different ecosystems, although its effect at the population and tree levels seems to be negative or neutral. Asynchrony in species responses to environmental conditions was found to be one of the main drivers of this stabilizing process. However, the effect of species mixing on the stability of productivity, and the relative importance of the associated mechanisms, remain poorly understood in forest communities., We investigated the way mixing species influenced the TS of productivity in Pinus sylvestris L. and Fagus sylvatica L. forests, and attempted to determine the main drivers among overyielding, asynchrony between species annual growth responses to environmental conditions, and temporal shifts in species interactions. We used a network of 93 experimental plots distributed across Europe to compare the TS of basal area growth over a 15-year period (1999-2013) in mixed and monospecific forest stands at different organizational levels, namely the community, population and individual tree levels., Mixed stands showed a higher TS of basal area growth than monospecific stands at the community level, but not at the population or individual tree levels. The TS at the community level was related to asynchrony between species growth in mixtures, but not to overyielding nor to asynchrony between species growth in monospecific stands. Temporal shifts in species interactions were also related to asynchrony and to the mixing effect on the TS., Synthesis. Our findings confirm that species mixing can stabilize productivity at the community level, whereas there is a neutral or negative effect on stability at the population and individual tree levels. The contrasting findings regarding the relationships between the temporal stability and asynchrony in species growth in mixed and monospecific stands suggest that the main driver in the stabilizing process may be the temporal niche complementarity between species rather than differences in species' intrinsic responses to environmental conditions. [ABSTRACT FROM AUTHOR]

A long-term study of disease dynamics caused by the rust Uromyces valerianae in 31 discrete populations of Valeriana salina provides a rare opportunity to explore extended temporal patterns in the epidemiology of a natural host-pathogen metapopulation., Over a 28-year period, pathogen population dynamics varied across the metapopulation with disease incidence (presence/absence), prevalence (% plants infected) and severity (% leaf area covered by lesions) all showing strong population and year effects, indicative of heterogeneity among years and host populations in the suitability of conditions for the pathogen., Disease incidence within individual host populations was significantly affected by host population size, disease prevalence the previous year and the proximity of neighbouring populations infected in the current year. After accounting for these variables there was still a marked temporal component with winter sea level having a significant effect; as did summer rainfall in the second part of the study period (1997-2011)., Disease prevalence was also effected by host population size and disease prevalence in the previous year. However, it was less affected by spatial aspects of disease spread than was disease incidence. Winter sea level and June rainfall significantly affected disease prevalence., Assessment of disease impact on plant performance found strong variation in disease severity associated with the aspect and positioning of host populations. Plants growing in lower disease environments produced significantly more seeds than those growing in high disease sites., Significant variation in reaction to infection by U. valerianae was detected among plants within four populations and between these different populations., Synthesis. The epidemiology of Uromyces valerianae was highly influenced by host population size, previous disease and distance. After accounting for these factors, there was a clear temporal signal of change in disease incidence linked to winter sea level and summer rainfall. These patterns reinforce the importance of considering interactions in multiple populations over long periods of time in order to obtain a clear picture of the variability in disease-induced selection pressures across time and space. The behaviour of the pathogen fitted that predicted for a metapopulation with considerable asynchrony in epidemiological patterns among demes. [ABSTRACT FROM AUTHOR]

The diversity of many communities is changing due to local extinctions and invasions. Understanding the consequences of these changes is vital to their successful conservation, yet few studies have experimentally investigated how producer diversity affects the stability of higher trophic levels. Here, we show that producer diversity, when manipulated as the only independent variable in the presence of natural top-down forces, increases the stability of consumer abundance, biomass and diversity in a benthic marine community., Using four macroalgal species ( Codium fragile, Gracilaria tikvahiae, Gracilaria vermiculophylla and Gymnogongrus griffithsiae), we manipulated producer diversity (identity and richness) in a substitutive design to create seven treatments. Our treatments included four monocultures, two 3-species mixtures that differed only by including either the native or invasive Gracilaria and the complete four-species mixture. We followed the week-to-week dynamics of producer and consumer communities in each treatment concurrently for 12 weeks and quantified their temporal stability., We found that higher producer diversity increased the stability of a diverse, productive consumer community. Producer biomass production did not affect consumer production or diversity, suggesting that producer diversity was solely responsible for driving the mechanisms underlying the observed multitrophic diversity-stability relationships. Taken together, our results indicate that higher producer diversity directly increased consumer diversity by increasing overyielding and decreasing the temporal variance of this response variable and that this increased consumer diversity enhanced consumer stability via increased asynchrony among consumers., Synthesis. Our results suggest that the effects of producer diversity propagate upwards to maintain diversity and productivity at higher trophic levels, and thereby enhance the overall stability of food webs. [ABSTRACT FROM AUTHOR]

1. Roots account for > 50% of net primary production in many ecosystems and are widely accepted as playing a fundamental role in ecosystem carbon and nutrient cycling. Despite this, the timing and controls of root production and the relationships between root and leaf phenology are still poorly understood in many plant communities, making it challenging to elucidate broad scale patterns and to predict ecosystem responses to a changing climate. Here, we investigate and compare the extent of synchrony of community-level fine root and leaf production in 10 widespread sub-Arctic plant communities, including deciduous forest, evergreen shrub, deciduous shrub and sedge-dominated communities. 2. We show that across contrasting plant communities, timing of leaf production does not vary substantially, but there are considerable differences in timing of root production between woody plantand sedge-dominated vegetation. In sedge communities, root production occurs early in the growing season, soon after the peak of leaf production, whereas in woody plant communities, leaf and root production are highly asynchronous, with the majority of root production occurring late in the growing season. 3. Seasonal dynamics of root growth were not consistently correlated with soil temperature, suggesting that differences in timing of production relate to inherent differences between plant functional types. This raises important questions as to the drivers of root production, the functional reasons underlying these contrasting plant strategies, as well as the consequences for microbial communities and nutrient cycling of such contrasting timing of carbon inputs to soil. 4. Synthesis. We demonstrate that major differences exist in the synchrony of temporal dynamics of leaf and root production between woody plant and sedge-dominated sub-Arctic vegetation. The substantially greater asynchrony in root and leaf production in woody plants compared with sedges suggests that vegetation change associated with climate warming will result in significant shifts in timing of carbon fluxes to soil, and highlights the need for separate leaf and root components in ecosystem carbon and nutrient cycle models. [ABSTRACT FROM AUTHOR]

Plant reproductive phenology is generally viewed as an individual's strategy to maximize gamete exchange and propagule dispersal and is often considered largely dependent on patterns of floral initiation. Reproductive phenology, however, can be affected by proximate responses to pollinators, parasites and herbivores which could influence floral longevity or fruit development time., We examined the influence of insect interactants on within-plant reproductive phenology in the fig-fig wasp nursery pollination mutualism in Ficus racemosa (Moraceae). Most figs support a wasp community comprised of a mutualistic pollinator, with several host-plant-specific non-pollinating herbivorous gallers and parasitoids. These wasps reproduce within enclosed inflorescences called syconia, which develop into fruit after pollination. While different wasp species oviposit into syconia at varying times during its ontogeny, all wasp progeny are constrained to exit syconia simultaneously just prior to fruit ripening. Developing larvae of early-ovipositing wasps may hasten syconium ontogeny through formation of earlier and larger nutrient sinks, whereas larvae of late-arriving parasites may lengthen syconium ontogeny to complete their development successfully. Seeds are also important nutrient sinks. The number of seeds and the type and number of developing wasps may therefore be expected to influence syconium development times, thereby affecting the reproductive synchrony of syconia on a plant., Observations on naturally pollinated and parasitized syconia indicated that their seed and wasp content affected syconium development time. Experimental manipulations of syconia to produce only seeds or various combinations of wasps confirmed this finding. Early-ovipositing galler progeny reduced syconium development times, while gallers ovipositing concurrently with pollinators had no effect on syconium development. Late-ovipositing parasitoid progeny, the presence of only seeds within the syconium, or delayed pollination increased syconium development time. The differential development of syconia, which was influenced by mutualistic or parasitic progeny, accordingly contributed to within-tree reproductive asynchrony., Synthesis. Individual reproductive units in fig trees called syconia, which also function as brood sites for pollinating and parasitic fig wasps, have plastic development durations dependent on pollination timing and species of wasps developing within them. Syconium development times are a likely compromise between conflicting demands from developing seeds and different wasp species. [ABSTRACT FROM AUTHOR]

Summary1 Analysis of the dynamics of rust disease caused by Uromyces valerianae in 30 discrete populations of Valeriana salina occurring on an archipelago of small islands in the Gulf of Bothnia, central Sweden, showed strong temporal and spatial effects. 2 Over a 13-year period, the population dynamics of the pathogen varied across the metapopulation, with disease incidence (presence/absence), prevalence and severity all showing strong population and year effects, indicative of heterogeneity among years and host populations in the suitability of conditions for the pathogen. While some individual populations were infected for the entire study period, others were infected for only 1 or 2 years. Local pathogen population extinction and recolonization events were relatively common, with annual recolonization rates of previously healthy populations ranging from 0% to 13.3%. 3 The incidence of disease within individual host populations was significantly affected by host population size, the prevalence of disease in the previous year and the proximity of neighbouring populations that were infected in the current year. The prevalence of disease in infected populations only depended on the prevalence of disease in the previous year. There was little to choose between disease prevalence and severity in predictive power. 4 Overall, the dynamical behaviour of this set of pathogen demes best fit that predicted for a metapopulation with considerable asynchrony in epidemiological patterns between different demes, despite evidence of among-population migration. [ABSTRACT FROM AUTHOR]