Dominant species, rather than diversity, regulates temporal stability of plant communities

Temporal turnover in species' ranks can explain variation in Taylor's slope for ecological timeseries

The scaling exponent relating the mean and variance of the density of individual organisms in space (i.e., Taylor's slope: zspace) is well studied in ecology, but the analogous scaling exponent for temporal datasets (ztime) is underdeveloped. Previous theory suggests the narrow distribution of ztime (e.g., typically 1-2) could be due to interspecific competition. Here, using 1694 communities time series, we show that ztime can exceed 2, and reaffirm how this can affect our inference about the stabilizing effect of biodiversity. We also develop a new theory, based on temporal change in the ranks of species abundances, to help account for the observed ztime distribution. Specifically, we find that communities with minimal turnover in species' rank abundances are more likely to have higher ztime. Our analysis shows how species-level variability affects our inference about the stability of ecological communities.

Mowing increased community stability in semiarid grasslands more than either fencing or grazing

A substantial body of empirical evidence suggests that anthropogenic disturbance can affect the structure and function of grassland ecosystems. Despite this, few studies have elucidated the mechanisms through which grazing and mowing, the two most widespread land management practices, affect the stability of natural grassland communities. In this study, we draw upon 9 years of field data from natural grasslands in northern China to investigate the effects of gazing and mowing on community stability, specifically focusing on community aboveground net primary productivity (ANPP) and dominance, which are two major biodiversity mechanisms known to characterize community fluctuations. We found that both grazing and mowing reduced ANPP in comparison to areas enclosed by fencing. Grazing reduced community stability by increasing the likelihood of single-species dominance and decreasing the relative proportion of nondominant species. In contrast, mowing reduced the productivity of the dominant species but increased the productivity of nondominant species. As a consequence, mowing improved the overall community stability by increasing the stability of nondominant species. Our study provides novel insight into understanding of the relationship between community species fluctuation-stability, with implications for ecological research and ecosystem management in natural grasslands.

Aridity-dependent shifts in biodiversity-stability relationships but not in underlying mechanisms

Climate change will affect the way biodiversity influences the stability of plant communities. Although biodiversity, associated species asynchrony, and species stability could enhance community stability, the understanding of potential nonlinear shifts in the biodiversity-stability relationship across a wide range of aridity (measured as the aridity index, the precipitation/potential evapotranspiration ratio) gradients and the underlying mechanisms remain limited. Using an 8-year dataset from 687 sites in Mongolia, which included 5496 records of vegetation and productivity, we found that the temporal stability of plant communities decreased more rapidly in more arid areas than in less arid areas. The result suggests that future aridification across terrestrial ecosystems may adversely affect community stability. Additionally, we identified nonlinear shifts in the effects of species richness and species synchrony on temporal community stability along the aridity gradient. Species synchrony was a primary driver of community stability, which was consistently negatively affected by species richness while being positively affected by the synchrony between C3 and C4 species across the aridity gradient. These results highlight the crucial role of C4 species in stabilizing communities through differential responses to interannual climate variations between C3 and C4 species. Notably, species richness and the synchrony between C3 and C4 species independently regulated species synchrony, ultimately affecting community stability. We propose that maintaining plant communities with a high diversity of C3 and C4 species will be key to enhancing community stability across Mongolian grasslands. Moreover, species synchrony, species stability, species richness and the synchrony between C3 and C4 species across the aridity gradient consistently mediated the impacts of aridity on community stability. Hence, strategies aimed at promoting the maintenance of biological diversity and composition will help ecosystems adapt to climate change or mitigate its adverse effects on ecosystem stability.

Establishing peat-forming plant communities: A comparison of wetland reclamation methods in Alberta's oil sands region

The Sandhill Wetland (SW) and Nikanotee Fen (NF) are two wetland research projects designed to test the viability of peatland reclamation in the Alberta oil sands post-mining landscape. To identify effective approaches for establishing peat-forming vegetation in reclaimed wetlands, we evaluated how plant introduction approaches and water level gradients influence species distribution, plant community development, and the establishment of bryophyte and peatland species richness and cover. Plant introduction approaches included seeding with a Carex aquatilis-dominated seed mix, planting C. aquatilis and Juncus balticus seedlings, and spreading a harvested moss layer transfer. Establishment was assessed 6 years after the introduction at SW and 5 years after the introduction at NF. In total, 51 species were introduced to the reclaimed wetlands, and 122 species were observed after 5 and 6 years. The most abundant species in both reclaimed wetlands was C. aquatilis, which produced dense canopies and occupied the largest water level range of observed plants. Introducing C. aquatilis also helped to exclude marsh plants such as Typha latifolia that has little to no peat accumulation potential. Juncus balticus persisted where the water table was lower and encouraged the formation of a diverse peatland community and facilitated bryophyte establishment. Various bryophytes colonized suitable areas, but the moss layer transfer increased the cover of desirable peat-forming mosses. Communities with the highest bryophyte and peatland species richness and cover (averaging 9 and 14 species, and 50%-160% cover respectively) occurred where the summer water level was between -10 and -40 cm. Outside this water level range, a marsh community of Typha latifolia dominated in standing water and a wet meadow upland community of Calamagrostis canadensis and woody species established where the water table was deeper. Overall, the two wetland reclamation projects demonstrated that establishing peat-forming vascular plants and bryophytes is possible, and community formation is dependent upon water level and plant introduction approaches. Future projects should aim to create microtopography with water tables within 40 cm of the surface and introduce vascular plants such as J. balticus that facilitate bryophyte establishment and support the development of a diverse peatland plant community.

Geographical, climatic, and soil factors control the altitudinal pattern of rhizosphere microbial diversity and its driving effect on root zone soil multifunctionality in mountain ecosystems

Shifts in rhizosphere soil microorganisms of dominant plants' response to climate change profoundly impact mountain soil ecosystem multifunctionality; relatively little is known about the relationship between them and how they depend on long-term environmental drivers. Here, we conducted analyses of rhizosphere microbial altitudinal pattern, community assembly, and co-occurrence network of 6 dominant plants in six typical vegetation zones ranging from 1350 to 2900 m (a.s.l.) in Helan Mountains by absolute quantitative sequencing technology, and finally related the microbiomes to root zone soil multifunctionality ('soil multifunctionality' hereafter), the environmental dependence of the relationship was explored. It was found that the altitudinal pattern of rhizosphere soil bacterial and fungal diversities differed significantly. Higher co-occurrence and more potential interactions of Stipa breviflora and Carex coninux were found at the lowest and highest altitudes. Bacterial α diversity, the identity of some dominant bacterial and fungal taxa, had significant positive or negative effects on soil multifunctionality. The effect sizes of positive effects of microbial diversity on soil multifunctionality were greater than those of negative effects. These results indicated that the balance of positive and negative effects of microbes determines the impact of microbial diversity on soil multifunctionality. As the number of microbes at the phylum level increases, there will be a net gain in soil multifunctionality. Our study reveals that geographical and climatic factors can directly or modulate the effects of soil properties on rhizosphere microbial diversity, thereby affecting the driving effect of microbial diversity on soil multifunctionality, and points to the rhizosphere bacterial diversity rather than the fungi being strongly associated with soil multifunctionality. This work has important ecological implications for predicting how multiple environment-plant-soil-microorganisms interactions in mountain ecosystems will respond to future climate change.

Long-term fencing can't benefit plant and microbial network stability of alpine meadow and alpine steppe in Three-River-Source National Park

A great number of fencing facilities has been established in Three-River-Source National Park. However, with the transformation of wild animals into the main consumers of grassland ecosystem and the increasing years of fence (>15 years), whether the fence still has a positive effect on grassland ecosystem has become controversial. Therefore, taking the alpine steppe and alpine meadow in Three-River-Source National Park as the case study, this study focused on the effects of long-term enclosure on different ecological components by investigating plant communities, soil physical and chemical characteristics and soil microbial characteristics (16S, ITS). Furthermore, we evaluated the ecological benefits of long-term fencing based on the stability of plant communities and microbial networks. We found that fencing did not significantly promote the stability of plant community in different grassland types. The analysis of bacteria-fungal symbiotic network indicated that fencing significantly reduced the stability of soil microbial network in alpine meadows. The results of structural equation showed that the microbial community was indirectly affected by the changes of soil moisture content (SMC) and soil total nutrient content in the alpine steppe, and the stability of microbial network was significantly correlated with the diversity of fungal community. In alpine meadows, fencing indirectly affected soil microbial community by changing SMC and pH. High SMC was not conducive to microbial network stability, while high plant community stability was beneficial to microbial network stability. Network stability was remarkably related to bacterial community composition and diversity, as well as fungal community diversity. Therefore, in Three-River-Source National Park, the positive effects of long-term fencing on various components in different grassland types are weak, especially the negative effects on the stability of soil microbial community in alpine meadows may also weaken the stability of the ecosystem, which is not conducive to the ecological protection of grassland ecosystem.

Biomass carbon sink stability of conifer and broadleaf boreal forests: differently associated with plant diversity and mycorrhizal symbionts?

Forest biomass carbon stability is crucial in achieving carbon neutrality in the high-latitude northern hemisphere, and identifying the differences among forest types and decoupling their associations with plant traits and geoclimatic conditions is the basis for precise forest management. We conducted a large-scale field survey in state-owned forest areas in northeastern China, covering a total of 280,000 km2 forest area, 1275 arbor plots (30 m × 30 m), 5285 shrub plots (5 m × 5 m), and 7076 herb plots (1 m × 1 m). We hypothesized that the conifer and broadleaf forest differences in biomass carbon (C) storage and stability (environmental stability to climatic changes-ES and recalcitrant stability to be decomposed-RS) are associated with mycorrhizal abundance (EcM: ectomycorrhizal, AM: arbuscular mycorrhizal, NM-AM: non-mycorrhizal or arbuscular mycorrhizal), taxon diversity traits (richness, Simpson, Shannon-Wiener, and evenness), and structural differences (diameter, height, and density) in the arbor, shrub, and herb layers. Our results showed that (1) conifer forests had 13.1 Mg/ha higher C stocks and 30.9% higher RS, but 8.6% lower ES than broadleaf forests (p < 0.05). Trees in conifer forests had 1.5 m taller and 2.4 cm thicker trees, but 15% less tree density than those in broadleaf forests. Herbs in conifer forests were 14% shorter and 57% denser than in broadleaf forests. (2) The abundance of EcM-symbiont trees in conifer forests was 15% higher than in broadleaf forests, while their EcM-symbiont shrubs and AM-symbiont herbs were 5-6% lower (p < 0.05). Broadleaf forests had 7% higher tree richness and 19% higher herb richness but 9% lower shrub richness than conifer forests (p < 0.05). Tree and herb evenness was 5-6% higher in conifer forests (p < 0.05). (3) Variations of biomass C sink traits could be explained more by plant diversity in conifer forests (7%) than in broadleaf forests (3.4%). Mycorrhizal symbionts could explain more in broadleaf forests (9.7%) than conifer forests (6.7%). In conifer forests, fewer EcM trees (higher AM trees) and AM herbs, higher tree richness were accompanied by higher biomass C storage and ES. Broadleaf forests underwent similar changes, characterized by an elevation in both RS and ES. (4) Our research emphasized that variations in carbon sequestration between conifer and broadleaf forests could be attributed to mycorrhizal symbionts and species diversity besides tree size-related structural differences. Our findings support the precise management of boreal forests to achieve carbon neutrality based on leaf blade types, plant diversity, and mycorrhizal symbionts.

The stability of perennial grasses mediates the negative impacts of long-term warming and increasing precipitation on community stability in a desert steppe

Background

Desert steppe, as an ecotone between desert and grassland, has few species and is sensitive to climate change. Climate change alters species diversity and the stability of functional groups, which may positively or negatively affect community stability. However, the response of plant community stability in the desert steppe to experimental warming and increasing precipitation remains largely unexplored.

Methods

In a factorial experiment of warming and increasing precipitation for five to seven years (ambient precipitation (P0), ambient precipitation increased by 25% and 50% (P1 and P2), ambient temperature (W0), ambient temperature increased by 2°C and 4°C (W1 and W2)), we estimated the importance value (IV) of four functional groups (perennial grasses, semi-shrubs, perennial forbs and annual herbs), species diversity and community stability.

Results

Compared to W0P0, the IV of perennial grasses was reduced by 37.66% in W2P2, whereas the IV of perennial forbs increased by 48.96%. Although increasing precipitation and experimental warming significantly altered species composition, the effect on species diversity was insignificant (P > 0.05). In addition, increasing precipitation and experimental warming had a significant negative impact on community stability. The stability of perennial grasses significantly explained community stability.

Conclusion

Our results suggest that the small number of species in desert steppe limits the contribution of species diversity to regulating community stability. By contrast, maintaining high stability of perennial grasses can improve community stability in the desert steppe.

Warming-driven indirect effects on alpine grasslands: short-term gravel encroachment rapidly reshapes community structure and reduces community stability

The community stability is the main ability to resist and be resilient to climate changes. In a world of climate warming and melting glaciers, alpine gravel encroachment was occurring universally and threatening hillside grassland ecosystem. Gravel encroachment caused by climate warming and glacial melting may alter community structure and community stability in alpine meadow. Yet, the effects of climate warming-induced gravel encroachment on grassland communities are unknown. Here, a 1-year short-term field experiment was conducted to explore the early stage drive process of gravel encroachment on community structure and stability at four different gravel encroachment levels 0%, 30%, 60%, and 90% gravel coverage at an alpine meadow on the Qinghai Tibetan Plateau, by analyzing the changes of dominant species stability and species asynchrony to the simulated gravel encroachment processes. Gravel encroachment rapidly changed the species composition and species ranking of alpine meadow plant community in a short period of time. Specifically, community stability of alpine meadow decreased by 61.78-79.48%, which may be due to the reduced dominant species stability and species asynchrony. Species asynchrony and dominant species stability were reduced by 2.65-17.39% and 46.51-67.97%, respectively. The results of this study demonstrate that gravel encroachment presents a severe negative impact on community structure and stability of alpine meadow in the short term, the longer term and comprehensive study should be conducted to accurate prediction of global warming-induced indirect effects on alpine grassland ecosystems.

The two sides of resistance-resilience relationship in both aboveground and belowground communities in the Eurasian steppe

The ongoing nitrogen (N) deposition has led to profound changes in aboveground and belowground ecosystems. However, the stability of plant and soil microbial community toward N addition in terms of resistance and resilience is less understood. We established a long-running field trial (2008-2018) in a series of N applications in combination with a mowing and fencing (unmown) treatment in a semiarid steppe. We assessed the resistance via ongoing N treatment of one subplot and the resilience via discontinuing N treatment in another to promote natural recovery since 2014. Plant resistance was negatively correlated with N application rate, while microbial resistance was independent of N rate. Mowing significantly reduced plant resistance and resilience, reduced soil microbial resistance but improved its resilience. Generally, plants are more resilient but less resistant to N than soil microbes. The two sides of resistance-resilience relationship were revealed: trade-offs exist between resistance and resilience for both plants and microbes at the community level; and trade-offs between resistance and resilience cannot be scaled down to species/group level. This study provided an important theoretical basis for the recovery and conservation of semiarid steppe and new insight into resistance-resilience relationship.

Shifting biomass allocation and light limitation co-regulate the temporal stability of an alpine meadow under eutrophication

Eutrophication generally promotes but destabilizes grassland productivity. Under eutrophication, plants tend to decrease biomass allocation to roots but increase aboveground allocation and light limitation, likely affecting community stability. However, it remains unclear to understand how shifting plant biomass allocation and light limitation regulate grassland stability in response to eutrophication. Here, using a 5-yr multiple nutrient addition experiment in an alpine meadow, we explored the role of changes in plant biomass allocation and light limitation on its community stability under eutrophication as well as traditionally established mechanisms (i.e., plant Shannon diversity, species asynchrony and grass subcommunity stability). Our results showed that nitrogen (N) addition, rather than phosphorus (P) or potassium (K) addition, significantly reduced the temporal stability of the alpine meadow. In accordance with previous studies, we found that N addition decreased plant Shannon diversity, species asynchrony and grass subcommunity stability, further destabilizing meadow community productivity. In addition, we also found the decrease in biomass allocation to belowground by N addition, further weakening its community stability. Moreover, this shifts in plant biomass allocation from below- to aboveground, intensifying plant light limitation. Further, the light limitation reduced plant species asynchrony, which finally weakened its community stability. Overall, in addition to traditionally established mechanisms, this study highlights the role of plant biomass allocation shifting from belowground to aboveground in determining grassland community stability. These "unseen" mechanisms might improve our understanding of grassland stability in the context of ongoing eutrophication.

Vertical Columns with Sustainable Green Cover: Meadow Plants in Urban Design

Unique vertical column structures were constructed for the greening of a structure at the Botanical Garden of Vilnius University, in which a plant cover was formed using the turf rolls of semi-natural meadows that were wrapped on 197 columns, with each column consisting of three equal segments. By evaluating the species composition and the abundance of vegetation in the segments of the columns, we studied how this natural cover changes and what its survival potential is. During the five years of observation, 97 plant species were determined in total. Over time, the initial plant species of fertile soils were mostly replaced by ruderal, nitrophilous, and pioneer plants. Out of the 58 original species, 18 disappeared, while 39 new ones emerged. In the vegetation cover on the north exposition of the building, the original species composition declined faster. The most persistent species were ruderal short-lived Conyza canadensis, Melilotus albus, and Urtica dioica, and long-lived Elytrigia repens. As for vegetation classes, the initial plant communities of the Molinio-Arrhenatheretea elatioris vegetation class were partially replaced by the plant communities of the Koelerio-Corynephoretea canescentis and Artemisietea vulgaris classes; however, unformed plant communities finally became prevalent. All directions, including the north, east, south and west, were equally dominated by semi-shade- and semi-light-loving plant species, together with a less abundant representation of light-loving species. Meanwhile, an unexpected establishment of the light-loving annual Arabidopsis arenosa was observed on the least illuminated north exposition. Likewise, the perennial Festuca pratensis, which is particularly resistant to wintering, emerged and spread on all expositions. The vegetation in the vertical columns was dynamic, and the initial plant species significantly diminished in the five years; however, as new species took place, the columns remained sufficiently covered with a green carpet of plants. This study reveals the benefits of using semi-natural meadow turfs in vertical greening of buildings in the harsh climate of a 5b hardiness zone, which is accompanied by distressing climatic fluctuations during the vegetation season.

Cryptogam plant community stability: Warming weakens influences of species richness but enhances effects of evenness

Community stability is a fundamental factor sustaining ecosystem functioning and is affected by species richness and species evenness. The Arctic is warming more rapidly than other biomes, and cryptogam plant species (specifically lichens and bryophytes in this study) are major contributors to tundra biodiversity and productivity. However, to our knowledge, the impacts of warming on cryptogam community stability and the underlying mechanisms have not been investigated. We conducted a 13-year summer warming experiment in mesic birch hummock tundra vegetation near Daring Lake in the continental interior of low Arctic Canada and recorded patterns of cryptogam species abundance in several different growing seasons. Warming decreased the stability of total community abundance, had no effects on species richness, but increased species evenness and species synchrony. Structural equation model analyses indicated that higher species richness was the principal factor associated with the stronger community abundance stability in the control plots and that this effect was driven primarily by a negative correlation with species synchrony. By contrast, higher species evenness was the principal factor associated with the weakened community abundance stability in the warming plots, and this effect was driven primarily by a positive correlation with species synchrony. Our study suggests that climate warming could reduce cryptogam plant community stability in low Arctic tundra and, therefore, decrease important ecosystem services, including carbon storage and food availability to caribou in northern regions.

Temporal stability of productivity is associated with complementarity and competitive intensities in intercropping

Year-to-year stability in crop production is a crucial aspect of feeding a growing global population. Evidence from natural ecosystems shows that increasing plant diversity generally increases the temporal stability of productivity; however, we have little knowledge of the mechanisms by which diversity affects stability. In fact, understanding the drivers of stability is a major knowledge gap in our understanding of biodiversity and ecosystem function in general. We varied resource inputs into crop monocultures and intercropping of maize/pea and maize/rapeseed for 3 years in field experiments to create a wide range of values for temporal stability, complementarity effects, selection effects, competition, and facilitation. We correlated whole-system temporal stability in productivity with these values and the stability of competitively subordinate species and competitively dominant species in the intercrops. We then used structural equation modeling (SEM), which combines complex path models with latent variables, to estimate how interspecific interactions for water, nitrogen, and phosphorus affected the relationships between stability and these values. Intercropping treatments did not increase stability, but the wide range of stability created by our experiments allowed us to explore the relationship of many factors with stability. Complementarity correlated positively with the temporal stability of grain yield and aboveground biomass, suggesting that either facilitative interactions or niche partitioning shifted over time in ways that promoted stability. Furthermore, the temporal stability of total productivity of intercropping relied most on the stability of more productive species. However, facilitation tested by relative interaction index independently did not correlate with stability, but the temporal stability of the whole system increased as the competitive effects of competitively dominant species (pea and rapeseed) on competitively subordinate species (maize) decreased and was highest when these competitive effects were virtually zero. SEM indicated that as competition for soil nitrogen from competitively dominant species on competitively subordinate species decreased, the overall temporal stability of whole-system aboveground biomass increased. This stability then led to greater stability in grain production. Our findings indicate that complex shifts in complementarity and competitive intensities are likely to be key mechanisms that maintain temporal stability in species-diverse agriculture and, potentially, in natural systems.

Leaf Photosynthetic and Functional Traits of Grassland Dominant Species in Response to Nutrient Addition on the Chinese Loess Plateau

Leaf photosynthetic and functional traits of dominant species are important for understanding grassland community dynamics under imbalanced nitrogen (N) and phosphorus (P) inputs. Here, the effects of N (N0, N50, and N100, corresponding to 0, 50, and 100 kg ha^-1 yr^-1, respectively) or/and P additions (P0, P40, and P80, corresponding to 0, 40, and 80 kg ha^-1 yr^-1) on photosynthetic characteristics and leaf economic traits of three dominant species (two grasses: Bothriochloa ischaemum and Stipa bungeana; a leguminous subshrub: Lespedeza davurica) were investigated in a semiarid grassland community on the Loess Plateau of China. Results showed that, after a three-year N addition, all three species had higher specific leaf area (SLA), leaf chlorophyll content (SPAD value), maximum net photosynthetic rate (P_Nmax), and leaf instantaneous water use efficiency (WUE), while also having a lower leaf dry matter content (LDMC). The two grasses, B. ischaemum and S. bungeana, showed greater increases in P_Nmax and SLA than the subshrub L. davurica. P addition alone had no noticeable effect on the P_Nmax of the two grasses while it significantly increased the P_Nmax of L. davurica. There was an evident synergetic effect of the addition of N and P combined on photosynthetic traits and most leaf economic traits in the three species. All species had relatively high P_Nmax and SLA under the addition of N50 combined with P40. Overall, this study suggests that N and P addition shifted leaf economic traits towards a greater light harvesting ability and, thus, elevated photosynthesis in the three dominant species of a semiarid grassland community, and this was achieved by species-specific responses in leaf functional traits. These results may provide insights into grassland restoration and the assessment of community development in the context of atmospheric N deposition and intensive agricultural fertilization.

Integrating natural gradients, experiments, and statistical modeling in a distributed network experiment: An example from the WaRM Network

A growing body of work examines the direct and indirect effects of climate change on ecosystems, typically by using manipulative experiments at a single site or performing meta‐analyses across many independent experiments. However, results from single‐site studies tend to have limited generality. Although meta‐analytic approaches can help overcome this by exploring trends across sites, the inherent limitations in combining disparate datasets from independent approaches remain a major challenge. In this paper, we present a globally distributed experimental network that can be used to disentangle the direct and indirect effects of climate change. We discuss how natural gradients, experimental approaches, and statistical techniques can be combined to best inform predictions about responses to climate change, and we present a globally distributed experiment that utilizes natural environmental gradients to better understand long‐term community and ecosystem responses to environmental change. The warming and (species) removal in mountains (WaRM) network employs experimental warming and plant species removals at high‐ and low‐elevation sites in a factorial design to examine the combined and relative effects of climatic warming and the loss of dominant species on community structure and ecosystem function, both above‐ and belowground. The experimental design of the network allows for increasingly common statistical approaches to further elucidate the direct and indirect effects of warming. We argue that combining ecological observations and experiments along gradients is a powerful approach to make stronger predictions of how ecosystems will function in a warming world as species are lost, or gained, in local communities.

Intra-annual growing season climate variability drives the community intra-annual stability of a temperate grassland by altering intra-annual species asynchrony and richness in Inner Mongolia, China

Understanding the factors that regulate the functioning of our ecosystems in response to environmental changes can help to maintain the stable provisioning of ecosystem services to mankind. This is especially relevant given the increased variability of environmental conditions due to human activities. In particular, maintaining a stable production and plant biomass during the growing season (intra‐annual stability) despite pervasive and directional changes in temperature and precipitation through time can help to secure food supply to wild animals, livestock, and humans. Here, we conducted a 29‐year field observational study in a temperate grassland to explore how the intra‐annual stability of primary productivity is influenced by biotic and abiotic variables through time. We found that intra‐annual precipitation variability in the growing season indirectly influenced the community intra‐annual biomass stability by its negative effect on intra‐annual species asynchrony. While the intra‐annual temperature variability in the growing season indirectly altered community intra‐annual biomass stability through affecting the intra‐annual species richness. At the same time, although the intra‐annual biomass stability of the dominant species and the dominant functional group were insensitive to climate variability, they also promoted the stable community biomass to a certain extent. Our results indicate that ongoing intra‐annual climate variability affects community intra‐annual biomass stability in the temperate grassland, which has important theoretical significance for us to take active measures to deal with climate change.

Functional identity of leaf dry matter content regulates community stability in the northern Tibetan grasslands

Biodiversity-stability mechanisms have been the focus of many long-term community stability studies. Community functional composition (i.e., functional diversity and functional identity of community plant functional traits) is critical for community stability; however, this topic has received less attention in large-scale studies. Here, we combined a field survey of biodiversity and plant functional traits in 22 alpine grassland sites throughout the northern Tibetan Plateau with 20 years of satellite-sensed proxy data (enhanced vegetation index) of community productivity to identify the factors influencing community stability. Our results showed that functional composition influenced community stability the most, explaining 61.71% of the variation in community stability (of which functional diversity explained 18.56% and functional identity explained 43.15%), which was a higher contribution than that of biodiversity (Berger-Parker index and species evenness; 35.04%). Structural equation modeling suggested that functional identity strongly affected community stability, whereas biodiversity had a minor impact. Furthermore, functional identity of leaf dry matter content regulated community stability by enhancing species dominance (Berger-Parker index). Our findings demonstrate that functional composition, specifically functional identity, plays a key role in community stability, highlighting the importance of functional identity in understanding and revealing the stabilizing mechanisms in these fragile alpine ecosystems which are subjected to increasing environmental fluctuations.

Different contributions of plant diversity and soil properties to the community stability in the arid desert ecosystem

As a one of the focuses of ecological research, understanding the regulation of plant diversity on community stability is helpful to reveal the adaption of plant to environmental changes. However, the relationship between plant diversity and community stability is still controversial due to the scale effect of its influencing factors. In this study, we compared the changes in community stability and different plant diversity (i.e., species, functional, and phylogenetic diversities) between three communities (i.e., riparian forest, ecotone community, and desert shrubs), and across three spatial scales (i.e., 100, 400, and 2500 m²), and then quantified the contribution of soil properties and plant diversity to community stability by using structural equation model (SEM) in the Ebinur Lake Basin Nature Reserve of the Xinjiang Uygur Autonomous Region in the NW China. The results showed that: (1) community stability differed among three communities (ecotone community > desert shrubs > riparian forest). The stability of three communities all decreased with the increase of spatial scale (2) species diversity, phylogenetic richness and the mean pairwise phylogenetic distance were higher in ecotone community than that in desert shrubs and riparian forest, while the mean nearest taxa distance showed as riparian forest > ecotone community > desert shrubs. (3) Soil ammonium nitrogen and total phosphorus had the significant direct negative and positive effects on the community stability, respectively. Soil ammonium nitrogen and total phosphorus also indirectly affected community stability by adjusting plant diversity. The interaction among species, functional and phylogenetic diversities also regulated the variation of community stability across the spatial scales. Our results suggested that the effect of plant diversities on community stability were greater than that of soil factors. The asynchronous effect caused by the changes in species composition and functional traits among communities had a positive impact on the stability. Our study provided a theoretical support for the conservation and management of biodiversity and community functions in desert areas.

Relationship between diversity and stability of a karst plant community

The relationships among species diversity, functional diversity, functional redundancy, and community stability are central to community and ecosystem ecology. In this paper, a "space substitution for time" approach is used to study the plant communities at different stages of the natural recovery process of degraded karst vegetation on the karst plateau of Guizhou. These restoration stages include the herbaceous stage, herbaceous and shrub transition stage, shrub stage, tree and shrub transition stage, and tree stage. We calculated the functional diversity and functional redundancy of the community based on functional characteristics and mediated the relationship between functional diversity, functional redundancy, and stability of the plant community through changes in functional diversity and functional redundancy. This study aims to reveal the mechanisms of changes in species diversity and community stability and thus further reveals the intrinsic reasons for maintaining the stability of karst plant communities. The most important results include the following: (1) Species diversity, functional redundancy, and stability gradually increased with restoration, and there were significant differences among the different stages; functional diversity increased at first and then decreased, and reached the highest level at the tree and shrub transition stage; (2) Plant height and specific leaf area were functional traits that influenced the diversity and stability of the plant community, with plant height being positively correlated with plant community diversity and stability, and specific leaf area being negatively correlated with plant community diversity and stability; (3) During the community's recovery, functional diversity and functional redundancy interacted to maintain stability. In the early and late stages of recovery, the effect of functional redundancy on stability was greater than that of functional diversity, but it was the opposite in the middle stages; (4) The tree and shrub transition stage is the likely point at which the functional diversity of plant communities in karst areas reaches saturation, and the growth rate of functional redundancy after functional diversity saturation is greater than that before saturation. Overall, community stability increased with species diversity; habitat heterogeneity increased functional diversity in the early stages of recovery; and habitat homogeneity increased functional redundancy.

The ecosystem impacts of dominant species exclusion in a prairie restoration

Dominant species often have disproportionately high abundance in restored communities compared to native remnants, which potentially could reduce the conservation value of restorations. Research is needed to determine how the abundance of dominant species in restoration plantings affects community assembly, species diversity, and ecosystem function. Most studies of dominant species in grasslands were modeled after experiments on keystone species, using the short-term experimental removal of dominants to test their functional role in ecosystems. However, the removal of established dominants constitutes a major disturbance that may influence the interpretation of their long-term functional impact. To address this, we experimentally assembled high-diversity tallgrass prairie communities that included or excluded the predicted dominant species (Andropogon gerardii and Sorghastrum nutans) from the seed mix at the time of planting, but without further manipulation of community composition. From 2013 to 2019, we measured several ecosystem functions and community dynamics in the presence or absence of dominants. Communities that included the dominant species had lower species richness, greater aboveground biomass, and reduced light availability at the soil surface. Dominant species presence also increased soil nutrient availability and rates of litter decomposition, although dominant grass litter decomposed more slowly than litter from other common species in both treatments. In the absence of the dominant grasses, communities were instead dominated by a common unplanted forb, Solidago altissima, and there was partial compensation in ecosystem functioning in these forb-dominated communities. The effects of dominant species exclusion may only be apparent in long-term studies of experimentally assembled communities that avoid the legacy effects associated with removal experiments. Furthermore, our results suggest that prairie restorations that limit or exclude the dominant grasses in seed mixes may achieve higher species diversity, increasing the conservation value of these systems.

Herbivory and Drought Reduce the Temporal Stability of Herbaceous Cover by Increasing Synchrony in a Semi-arid Savanna

Ecological stability in plant communities is shaped by bottom-up processes like environmental resource fluctuations and top-down controls such as herbivory, each of which have demonstrated direct effects but may also act indirectly by altering plant community dynamics. These indirect effects, called biotic stability mechanisms, have been studied across environmental gradients, but few studies have assessed the importance of top-down controls on biotic stability mechanisms in conjunction with bottom-up processes. Here we use a long-term herbivore exclusion experiment in central Kenya to explore the joint effects of drought and herbivory (bottom-up and top-down limitation, respectively) on three biotic stability mechanisms: (1) species asynchrony, in which a decline in one species is compensated for by a rise in another, (2) stable dominant species driving overall stability, and (3) the portfolio effect, in which a community property is distributed among multiple species. We calculated the temporal stability of herbaceous cover and biotic stability mechanisms over a 22-year time series and with a moving window to examine changes through time. Both drought and herbivory additively reduced asynchronous dynamics, leading to lower stability during droughts and under high herbivore pressure. This effect is likely attributed to a reduction in palatable dominant species under higher herbivory, which creates space for subordinate species to fluctuate synchronously in response to rainfall variability. Dominant species population stability promoted community stability, an effect that did not vary with precipitation but depended on herbivory. The portfolio effect was not important for stability in this system. Our results demonstrate that this system is naturally dynamic, and a future of increasing drought may reduce its stability. However, these effects will in turn be amplified or buffered depending on changes in herbivore communities and their direct and indirect impacts on plant community dynamics.

Independent Effects of Species Removal and Asynchrony on Invariability of an Intertidal Rocky Shore Community

Ecological stability depends on interactions between different levels of biological organization. The insurance effects occur when increasing species diversity leads to more temporally invariable (i.e., more stable) community-level properties, due in part to asynchronous population-level fluctuations. While the study of insurance effects has received considerable attention, the role of dominant species that contribute with particular functional traits across different level of organizations is less understood. Using a field-based manipulative experiment, we investigated how species richness and different types of parameters at the population level, such as the invariability of dominants, population invariability, and population asynchrony, influence the community invariability. The experiment involved the repetitive removal of the canopy forming alga Mazzaella laminarioides (hereafter “Mazzaella”) during 32 months in two rocky intertidal sites of northern-central Chile. We predicted that the invariability of dominants enhances community invariability, that the effect of multispecies population-level parameters on community invariability are dependent on species richness, and that subdominant algae are unable to fully compensate the loss of canopies of the dominant species. Biomass of algae and mobile invertebrates was quantified over time. We observed independent effects of Mazzaella removal and community-wide asynchrony on community invariability. While canopy removal reduced community invariability, population asynchrony boosted community invariability regardless of the presence of canopies. In addition, filamentous and foliose algae were unable to compensate the loss of biomass triggered by the experimental removal of Mazzaella. Canopy removal led to a severe decrement in the biomass of macrograzers, while, at the same time, increased the biomass of mesograzers. Asynchrony stemmed from compensatory trophic responses of mesograzers to increased abundances of opportunistic algae. Thus, further work on consumer-resource interactions will improve our understanding of the links between population- and community-level aspects of stability.

Linking leaf traits to the temporal stability of above- and belowground productivity under global change and land use scenarios in a semi-arid grassland of Inner Mongolia

The biotic drivers for the temporal stability of aboveground net productivity (ANPP) in natural ecosystems are well understood. However, knowledge gaps still exist regarding the relative importance of biotic and abiotic drivers regulating the temporal stability of aboveground productivity (ANPP), belowground net productivity (BNPP), and community net productivity (NPP) under global change and land use scenarios. Thus, in this study, we aimed to study the effects of increased water and nitrogen availability on temporal stability of ANPP, BNPP, and NPP and underlying mechanisms at sites with different long-term grazing histories in typical grasslands of the Inner Mongolia. The results suggested that resource addition affected the ANPP stability, but it did not change the stability of BNPP and NPP, which were all mediated by grazing histories. Most importantly, our study further indicated that species asynchrony, primarily contributed to the stability of ANPP and NPP by weakening their variation, and species asynchrony was regulated directly by plant diversity-related variables and indirectly by soil variables which were affected by resource addition and grazing history. In addition, an increase of ANPP stimulated under resource addition was a secondary contributor to ANPP stability. Specifically, the community-weighted mean of specific leaf area (CWM SLA) regulated the ANPP stability indirectly by promoting species asynchrony, while functional diversity of leaf area and SLA both directly controlled the BNPP stability. Findings of our study demonstrate that different mechanisms drove temporal stability of above- and belowground productivity. Our study has important implications for maintaining the temporal stability of community productivity and for establishing sustainable management practices of semi-arid grasslands under global change and land use scenarios.

Livestock exclusion reduces the temporal stability of grassland productivity regardless of eutrophication

Changes in livestock loads and eutrophication associated with human activities can modify the stability of grassland's aboveground net primary productivity (ANPP), by modifying the mean (μ) and/or standard deviation (σ) of ANPP. The changes in attributes of the plant community (i.e., species richness, species asynchrony, dominance) might in turn explain the ecosystem temporal (inter-annual) stability of grassland production. Here, we evaluated the interactive effects of changes in livestock loads and chronic nutrient addition on the temporal stability of ANPP (estimated as μ/σ) in temperate grasslands. We also assessed the role of different attributes of the plant community on ecosystem stability. We carried out a factorial experiment of domestic livestock exclusion and nutrient addition (10 g.m^-2.year^-1 of nitrogen, phosphorus, and potassium; n = 6 blocks) during five consecutive years in a natural grassland devoted to cattle production (Flooding Pampa, Argentina). Domestic livestock exclusion reduced ANPP stability by 65%, regardless of nutrient load, mainly by the increase of ANPP standard deviation. This reduction in ANPP stability after livestock exclusion was associated mostly with higher plant species dominance and also with reductions in plant effective richness and in the asynchrony of grassland's species. Despite not finding direct negative effects of eutrophication on ANPP stability, chronic nutrient addition decreased effective species richness and asynchrony, which may translate into reductions in ANPP stability in the future. Our findings highlight that the presence of livestock maintains the temporal stability of ANPP mainly by lowering the dominance of the plant community. However, increases in nutrient loads in grasslands devoted to livestock production may threaten grassland's stability.

Stability response of alpine meadow communities to temperature and precipitation changes on the Northern Tibetan Plateau

Biomass temporal stability plays a key role in maintaining sustainable ecosystem functions and services of grasslands, and climate change has exerted a profound impact on plant biomass. However, it remains unclear how the community biomass stability in alpine meadows responds to changes in some climate factors (e.g., temperature and precipitation). Long‐term field aboveground biomass monitoring was conducted in four alpine meadows (Haiyan [HY], Henan [HN], Gande [GD], and Qumalai [QML]) on the Qinghai‐Tibet Plateau. We found that climate factors and ecological factors together affected the community biomass stability and only the stability of HY had a significant decrease over the study period. The community biomass stability at each site was positively correlated with both the stability of the dominant functional group and functional groups asynchrony. The effect of dominant functional groups on community stability decreased with the increase of the effect of functional groups asynchrony on community stability and there may be a ‘trade‐off’ relationship between the effects of these two factors on community stability. Climatic factors directly or indirectly affect community biomass stability by influencing the stability of the dominant functional group or functional groups asynchrony. Air temperature and precipitation indirectly affected the community stability of HY and HN, but air temperature in the growing season and nongrowing season had direct negative and direct positive effects on the community stability of GD and QML, respectively. The underlying mechanisms varied between community composition and local climate conditions. Our findings highlighted the role of dominant functional group and functional groups asynchrony in maintaining community biomass stability in alpine meadows and we highlighted the importance of the environmental context when exploring the stability influence mechanism. Studies of community stability in alpine meadows along with different precipitation and temperature gradients are needed to improve our comprehensive understanding of the mechanisms controlling alpine meadow stability.

Climate variability supersedes grazing to determine the anatomy and physiology of a dominant grassland species

Grassland ecosystems are historically shaped by climate, fire, and grazing which are essential ecological drivers. These grassland drivers influence morphology and productivity of grasses via physiological processes, resulting in unique water and carbon-use strategies among species and populations. Leaf-level physiological responses in plants are constrained by the underlying anatomy, previously shown to reflect patterns of carbon assimilation and water-use in leaf tissues. However, the magnitude to which anatomy and physiology are impacted by grassland drivers remains unstudied. To address this knowledge gap, we sampled from three locations along a latitudinal gradient in the mesic grassland region of the central Great Plains, USA during the 2018 (drier) and 2019 (wetter) growing seasons. We measured annual biomass and forage quality at the plot level, while collecting physiological and anatomical traits at the leaf-level in cattle grazed and ungrazed locations at each site. Effects of ambient drought conditions superseded local grazing treatments and reduced carbon assimilation and total productivity in A. gerardii. Leaf-level anatomical traits, particularly those associated with water-use, varied within and across locations and between years. Specifically, xylem area increased when water was more available (2019), while xylem resistance to cavitation was observed to increase in the drier growing season (2018). Our results highlight the importance of multi-year studies in natural systems and how trait plasticity can serve as vital tool and offer insight to understanding future grassland responses from climate change as climate played a stronger role than grazing in shaping leaf physiology and anatomy.

Higher-order effects, continuous species interactions, and trait evolution shape microbial spatial dynamics

Persistently diverse microbial communities are one of biology’s great puzzles. Using a modeling framework that accommodates high mutation rates and a continuum of species traits, we studied microbial communities in which antagonistic interactions occur via the production of, inhibition of, and vulnerability to toxins (e.g., antibiotics). Mutation size and mobility enhanced microbial diversity and temporal persistence to extraordinarily high levels. These findings—including the discovery that the duration of the transient phase in community assembly provides a guide to equilibrial diversity—highlight the potentially critical role that antagonistic interactions play in promoting the diversity of bacterial systems. Such interactions, together with resource-driven interactions and spatial structure, may drive the enigmatic levels of biodiversity seen in microbial systems.

The assembly and maintenance of microbial diversity in natural communities, despite the abundance of toxin-based antagonistic interactions, presents major challenges for biological understanding. A common framework for investigating such antagonistic interactions involves cyclic dominance games with pairwise interactions. The incorporation of higher-order interactions in such models permits increased levels of microbial diversity, especially in communities in which antibiotic-producing, sensitive, and resistant strains coexist. However, most such models involve a small number of discrete species, assume a notion of pure cyclic dominance, and focus on low mutation rate regimes, none of which well represent the highly interlinked, quickly evolving, and continuous nature of microbial phenotypic space. Here, we present an alternative vision of spatial dynamics for microbial communities based on antagonistic interactions—one in which a large number of species interact in continuous phenotypic space, are capable of rapid mutation, and engage in both direct and higher-order interactions mediated by production of and resistance to antibiotics. Focusing on toxin production, vulnerability, and inhibition among species, we observe highly divergent patterns of diversity and spatial community dynamics. We find that species interaction constraints (rather than mobility) best predict spatiotemporal disturbance regimes, whereas community formation time, mobility, and mutation size best explain patterns of diversity. We also report an intriguing relationship among community formation time, spatial disturbance regimes, and diversity dynamics. This relationship, which suggests that both higher-order interactions and rapid evolution are critical for the origin and maintenance of microbial diversity, has broad-ranging links to the maintenance of diversity in other systems.

Species richness and asynchrony maintain the stability of primary productivity against seasonal climatic variability

The stability of grassland communities informs us about the ability of grasslands to provide reliable services despite environmental fluctuations. There is large evidence that higher plant diversity and asynchrony among species stabilizes grassland primary productivity against interannual climate variability. Whether biodiversity and asynchrony among species and functional groups stabilize grassland productivity against seasonal climate variability remains unknown. Here, using 29-year monitoring of a temperate grassland, we found lower community temporal stability with higher seasonal climate variability (temperature and precipitation). This was due to a combination of processes including related species richness, species asynchrony, functional group asynchrony and dominant species stability. Among those processes, functional group asynchrony had the strongest contribution to community compensatory dynamics and community stability. Based on a long-term study spanning 29 years, our results indicate that biodiversity and compensatory dynamics a key for the stable provision of grassland function against increasing seasonal climate variability.

Relationship between Tree Richness and Temporary Stability of Plant Communities: A Case Study of a Forest in Northeast China

The relationship between diversity and stability is a classic issue in ecology, but no general consensus has been achieved. To address this relationship, a field survey of a forest in Northeast China was conducted. The temporary stability was defined from the perspective of community characteristics. The results showed that communities with the highest temporary stability value were characterized by a single dominant species. A significant linear relationship with a low R2 value was observed between temporary stability and tree richness. When dominant and non-dominant tree species were studied, no significant linear relationship was obtained between temporary stability and non-dominant tree richness. However, the relationship between temporary stability and dominant tree richness was significant with a high R2 value, and the temporary stability decreased with increasing dominant tree richness. This study demonstrates that dominant tree richness is closely related to temporary stability, and temporary stability can serve as a stability indicator. The results provide a new perspective for understanding stability and additional information for revealing the relationship between diversity and stability in forest ecosystems.

Effects of plant diversity on semiarid grassland stability depends on functional group composition and dynamics under N and P addition

Exogenous fertilization could efficiently improve grassland productivity and promote grassland restoration. Increasing fertilization may profoundly affect community stability, whereas the underlying compensatory dynamics among functional groups in regulating grassland stability remain unclear. Three different grasslands, annuals forb (AF) community, perennial grass (PG) community and perennial forb (PF) community, on semiarid Loess Plateau were selected. We designed a 3-year split-plot experiment (main-plot: 0, 25, 50, and 100 kg N ha^-1 yr^-1; subplot: 0, 20, 40 and 80 kg P₂O₅ ha^-1 yr^-1) to explore how N and P addition affects community stability and its relationship with species richness, species asynchrony and functional group stability. Temporal stability differed largely between functional groups under N and P addition, perennial forbs or grasses had higher stability than perennial legumes or annuals and biennials. Decreased stability of PG and PF communities was primarily due to reduced species asynchrony under N addition alone, while it attributed to increased dominance of perennial legumes after P addition alone. 50 and 100 kg N ha^-1 yr^-1 combined with P addition significantly increased dominance of annuals and biennials, but decreased stability of annuals and biennials, which caused significant declines in stability of the three communities. Significant species richness decline induced by N and P addition only occurred in AF community, which suppressed AF community stability through reducing species asynchrony. AF community stability was regulated by additively negative effect of diversity decline and decreased annuals and biennials stability. Whereas, in PG and PF communities, nutrient-induced changes of functional groups stability were the main driver of community stability rather than diversity. Our study highlights the role of functional group composition and dynamics in regulating the effects of diversity on community stability and rational N and P combined addition was essential for conserving stability of different grasslands on semiarid Loess Plateau.

Dominant Plant Functional Group Determine the Response of the Temporal Stability of Plant Community Biomass to 9-Year Warming on the Qinghai-Tibetan Plateau

Ecosystem stability characterizes ecosystem responses to natural and anthropogenic disturbance and affects the feedback between ecosystem and climate. A 9-year warming experiment (2010-2018) was conducted to examine how climatic warming and its interaction with the soil moisture condition impact the temporal stability of plant community aboveground biomass (AGB) of an alpine meadow in the central Qinghai-Tibetan Plateau (QTP). Under a warming environment, the AGB percentage of grasses and forbs significantly increased but that of sedges decreased regardless of the soil water availability in the experimental plots. The warming effects on plant AGB varied with annual precipitation. In the dry condition, the AGB showed no significant change under warming in the normal and relatively wet years, but it significantly decreased in relatively drought years (16% in 2013 and 12% in 2015). In the wet condition, the AGB showed no significant change under warming in the normal and relatively drought years, while it significantly increased in relatively wet years (12% in 2018). Warming significantly decreased the temporal stability of AGB of plant community and sedges. Species richness remained stable even under the warming treatment in both the dry and wet conditions. The temporal stability of AGB of sedges (dominant plant functional group) explained 66.69% variance of the temporal stability of plant community AGB. Our findings highlight that the temporal stability of plant community AGB is largely regulated by the dominant plant functional group of alpine meadow that has a relatively low species diversity.

Negative impacts of dominance on bee communities: Does the influence of invasive honey bees differ from native bees?

Invasive species can reach high abundances and dominate native environments. One of the most impressive examples of ecological invasions is the spread of the African subspecies of the honey bee throughout the Americas, starting from its introduction in a single locality in Brazil. The invasive honey bee is expected to more negatively impact bee community abundance and diversity than native dominant species, but this has not been tested previously. We developed a comprehensive and systematic bee sampling scheme, using a protocol deploying 11,520 pan traps across regions and crops for three years in Brazil. We found that invasive honey bees are now the single most dominant bee species. Such dominance has not only negative consequences for abundance and species richness of native bees but also for overall bee abundance (i.e., strong "numerical" effects of honey bees). Contrary to expectations, honey bees did not have stronger negative impacts than other native bees achieving similar levels of dominance (i.e., lack of negative "identity" effects of honey bees). These effects were markedly consistent across crop species, seasons and years, and were independent from land-use effects. Dominance could be a proxy of bee community degradation and more generally of the severity of ecological invasions.

Defining codominance in plant communities

Species dominance and biodiversity in plant communities have received considerable attention and characterisation. However, species codominance, while often alleged, is seldom defined or quantified. Codominance is a common phenomenon and is likely to be an important driver of community structure, ecosystem function and the stability of both. Here we review the use of the term 'codominance' and find inconsistencies in its use, suggesting that the scientific community currently lacks a universal understanding of codominance. We address this issue by: (1) qualitatively defining codominance as mostly shared abundance that is distinctively isolated within a subset of a community, and (2) presenting a novel metric for quantifying the degree to which relative abundances are shared among a codominant subset of plant species, while also accounting for the remaining species within a plant community. Using both simulated and real-world data, we then demonstrate the process of applying the codominance metric to compare communities and to generate a quantitatively defensible subset of species to consider codominant within a community. We show that our metric effectively distinguishes the degree of codominance between four types of grassland ecosystems as well as simulated ecosystems with varying degrees of abundance sharing among community members. Overall, we make the case that increased research focusses on the conditions under which codominance occurs and the consequences for species coexistence, community structure and ecosystem function that would considerably advance the fields of community and ecosystem ecology.

Consistently positive effect of species diversity on ecosystem, but not population, temporal stability

Despite much recent progress, our understanding of diversity-stability relationships across different study systems remains incomplete. In particular, recent theory clarified that within-species population stability and among-species asynchronous population dynamics combine to determine ecosystem temporal stability, but their relative importance in modulating diversity-ecosystem temporal stability relationships in different ecosystems remains unclear. We addressed this issue with a meta-analysis of empirical studies of ecosystem and population temporal stability in relation to species diversity across a range of taxa and ecosystems. We show that ecosystem temporal stability tended to increase with species diversity, regardless of study systems. Increasing diversity promoted asynchrony, which, in turn, contributed to increased ecosystem stability. The positive diversity-ecosystem stability relationship persisted even after accounting for the influences of environmental covariates (e.g., precipitation and nutrient input). By contrast, species diversity tended to reduce population temporal stability in terrestrial systems but increase population temporal stability in aquatic systems, suggesting that asynchronous dynamics among species are essential for stabilizing diverse terrestrial ecosystems. We conclude that there is compelling empirical evidence for a general positive relationship between species diversity and ecosystem-level temporal stability, but the contrasting diversity-population temporal stability relationships between terrestrial and aquatic systems call for more investigations into their underlying mechanisms.

Plant community and the influence of plant taxonomic diversity on community stability and invasibility: A case study based on Solidago canadensis L

Invasive alien plants (IAPs) can negatively affect plant taxonomic diversity, community stability, and invasibility in the invaded habitats. This study aimed to assess the degree of influence of the IAP Solidago canadensis L. under various levels of invasion (i.e., light, moderate, and heavy invasion based on its relative abundance in the invaded communities) on plant taxonomic diversity, community stability, and invasibility. In addition, we determined the contribution of plant taxonomic diversity to community stability and invasibility under various levels of S. canadensis invasion. The degree of influence of S. canadensis on plant taxonomic diversity and community stability increases as the level of S. canadensis invasion increases. Community invasibility increases as the level of S. canadensis invasion increases. The competitive advantage of S. canadensis is negatively associated with all indexes of plant taxonomic diversity and community stability but positively connected with community invasibility. Community stability is positively related to Shannon's diversity and Simpson's dominance indexes but negatively associated with community invasibility. Inversely, communities were more likely to be invaded when they had less plant taxonomic diversity. Thus, plant communities with lower values of plant taxonomic diversity and community stability are more vulnerable to S. canadensis invasion. Plant diversity causes a greater pressure on community stability than the other indexes of plant taxonomic diversity under various levels of S. canadensis invasion. However, the contribution intensity of the number of plant species to community invasibility is higher than the other indexes of plant taxonomic diversity under various levels of S. canadensis invasion.

How complementarity and selection affect the relationship between ecosystem functioning and stability

The biotic mechanisms underlying ecosystem functioning and stability have been extensively-but separately-explored in the literature, making it difficult to understand the relationship between functioning and stability. In this study, we used community models to examine how complementarity and selection, the two major biodiversity mechanisms known to enhance ecosystem biomass production, affect ecosystem stability. Our analytic and simulation results show that although complementarity promotes stability, selection impairs it. The negative effects of selection on stability operate through weakening portfolio effects and selecting species that have high productivity but low tolerance to perturbations ("risk-prone" species). In contrast, complementarity enhances stability by increasing portfolio effects and reducing the relative abundance of risk-prone species. Consequently, ecosystem functioning and stability exhibit either a synergy, if complementarity effects prevail, or trade-off, if selection effects prevail. Across species richness levels, ecosystem functioning and stability tend to be positively related, but negative relationships can occur when selection co-varies with richness. Our findings provide novel insights for understanding the functioning-stability relationship, with potential implications for both ecological research and ecosystem management.

Wild insect diversity increases inter-annual stability in global crop pollinator communities

While an increasing number of studies indicate that the range, diversity and abundance of many wild pollinators has declined, the global area of pollinator-dependent crops has significantly increased over the last few decades. Crop pollination studies to date have mainly focused on either identifying different guilds pollinating various crops, or on factors driving spatial changes and turnover observed in these communities. The mechanisms driving temporal stability for ecosystem functioning and services, however, remain poorly understood. Our study quantifies temporal variability observed in crop pollinators in 21 different crops across multiple years at a global scale. Using data from 43 studies from six continents, we show that (i) higher pollinator diversity confers greater inter-annual stability in pollinator communities, (ii) temporal variation observed in pollinator abundance is primarily driven by the three-most dominant species, and (iii) crops in tropical regions demonstrate higher inter-annual variability in pollinator species richness than crops in temperate regions. We highlight the importance of recognizing wild pollinator diversity in agricultural landscapes to stabilize pollinator persistence across years to protect both biodiversity and crop pollination services. Short-term agricultural management practices aimed at dominant species for stabilizing pollination services need to be considered alongside longer term conservation goals focussed on maintaining and facilitating biodiversity to confer ecological stability.

Temperature effects on the temporal dynamics of a subarctic invertebrate community

Climate warming is predicted to have major impacts on the structure of terrestrial communities, particularly in high latitude ecosystems where growing seasons are short. Higher temperatures may dampen seasonal dynamics in community composition as a consequence of earlier snowmelt, with potentially cascading effects across all levels of biological organisation. Here, we examined changes in community assembly and structure along a natural soil temperature gradient in the Hengill geothermal valley, Iceland, during the summer of 2015. Sample collection over several time points within a season allowed us to assess whether temperature alters temporal variance in terrestrial communities and compositional turnover. We found that seasonal fluctuations in species richness, diversity and evenness were dampened as soil temperature increased, whereas invertebrate biomass varied more. Body mass was found to be a good predictor of species occurrence, with smaller species found at higher soil temperatures and emerging earlier in the season. Our results provide more in-depth understanding of the temporal nature of community and population-level responses to temperature, and indicate that climate warming will likely dampen the seasonal turnover of community structure that is characteristic of high latitude invertebrate communities.

Functional Diversity Can Predict Ecosystem Functions Better Than Dominant Species: The Case of Desert Plants in the Ebinur Lake Basin

Studying the impact of biodiversity on ecosystem multifunctionality is helpful for clarifying the ecological mechanisms (such as niche complementary effects and selection) of ecosystems providing multiple services. Biodiversity has a significant impact on ecosystem versatility, but the relative importance of functional diversity and dominant species to ecosystem functions needs further evaluation. We studied the desert plant community in Ebinur Lake Basin. Based on field survey data and experimental analysis, the relationship between the richness and functional diversity of dominant species and the single function of ecosystem was analyzed. The relative importance of niche complementary effect and selective effect in explaining the function of plant diversity in arid areas is discussed. There was no significant correlation between desert ecosystem functions (soil available phosphorus, organic matter, nitrate nitrogen, and ammonium nitrogen) and the richness of the dominant species Nitraria tangutorum (p < 0.05). Soil organic matter and available phosphorus had significant effects on specific leaf area and plant height (p < 0.05). Functional dispersion (FDis) had a significant effect on soil available phosphorus, while dominant species dominant species richness (SR) had no obvious effect on single ecosystem function. A structural equation model showed that dominant species had no direct effect on plant functional diversity and ecosystem function, but functional diversity had a strong direct effect on ecosystem function, and its direct coefficients of action were 0.226 and 0.422. The results can help to explain the response mechanism of multifunctionality to biodiversity in arid areas, which may provide referential significance for vegetation protection and restoration for other similar areas.

Revisiting ecological dominance in arboreal ants: how dominant usage of nesting resources shapes community assembly

Ecologically dominant species can shape the assembly of ecological communities via altering competitive outcomes. Moreover, these effects may be amplified under limited niche differentiation. Nevertheless, the influences of ecological dominance and niche differentiation on assembly are rarely considered together. Here, we provide a novel examination of dominance in a diverse arboreal ant community, defining dominance by the prevalent usage of nesting resources and addressing how it influences community assembly. We first used a series of quantitative observational and experimental studies to address the natural nesting ecology, colony incidence on surveyed trees, and level of dominance over newly available nesting resources by our focal species, Cephalotes pusillus. The experimental studies were then used further to examine whether C. pusillus shapes assembly via an influence on cavity usage by co-occurring species. C. pusillus was confirmed as a dominant user of cavity nesting resources, with highly generalized nesting ecology, occupying about 50% of the trees within the focal system, and accounting for more than a third of new cavity occupation in experiments. Our experiments showed further that the presence of C. pusillus was associated with modest effects on species richness, but significant decreases in cavity-occupation levels and significant shifts in the entrance-size usage by co-occurring species. These results indicate that C. pusillus, as a dominant user of nesting resources, shapes assembly at multiple levels. Broadly, our findings highlight that complex interactions between a dominant species and the resource-usage patterns of other species can underlie species assembly in diverse ecological communities.