Winning and losing with microbes: how microbially mediated fitness differences influence plant diversity

Interactions between plants and soil microbes can strongly influence plant diversity and community dynamics. Soil microbes may promote plant diversity by driving negative frequency‐dependent plant population dynamics, or may favor species exclusion by providing one species an average fitness advantage over others. However, past empirical research has focused overwhelmingly on the consequences of frequency‐dependent feedbacks for plant species coexistence and has generally neglected the consequences of microbially mediated average fitness differences. Here we use theory to develop metrics that quantify microbially mediated plant fitness differences, and show that accounting for these effects can profoundly change our understanding of how microbes influence plant diversity. We show that soil microbes can generate fitness differences that favour plant species exclusion when they disproportionately harm (or favour) one plant species over another, but these fitness differences may also favor coexistence if they trade off with competition for other resources or generate intransitive dominance hierarchies among plants. We also show how the metrics we present can quantify microbially mediated fitness differences in empirical studies, and explore how microbial control over coexistence varies along productivity gradients. In all, our analysis provides a more complete theoretical foundation for understanding how plant–microbe interactions influence plant diversity.     

The influence of biotic interactions on soil biodiversity

Belowground communities usually support a much greater diversity of organisms than do corresponding aboveground ones, and while the factors that regulate their diversity are far less well understood, a growing number of recent studies have presented data relevant to understanding how these factors operate. This review considers how biotic factors influence community diversity within major groups of soil organisms across a broad spectrum of spatial scales, and addresses the mechanisms involved. At the most local scale, soil biodiversity may potentially be affected by interactions within trophic levels or by direct trophic interactions. Within the soil, larger bodied invertebrates can also influence diversity of smaller sized organisms by promoting dispersal and through modification of the soil habitat. At larger scales, individual plant species effects, vegetation composition, plant species diversity, mixing of plant litter types, and aboveground trophic interactions, all impact on soil biodiversity. Further, at the landscape scale, soil diversity also responds to vegetation change and succession. This review also considers how a conceptual understanding of the biotic drivers of soil biodiversity may assist our knowledge of key topics in community and ecosystem ecology, such as aboveground–belowground interactions, and the relationship between biodiversity and ecosystem functioning. It is concluded that an improved understanding of what drives the diversity of life in the soil, incorporated within appropriate conceptual frameworks, should significantly aid our understanding of the structure and functioning of terrestrial communities.     

Scale-dependent shifts in the species composition of flower visitors with changing floral density

Responses of flower-visiting animals to floral density can alter interactions between plants, influencing a variety of biological processes, including plant population dynamics and the evolution of flowering phenology. Many studies have found effects of floral or plant density on pollinator visitation rates at patch scales, but little is known about responses of flower visitors to floral densities at larger scales. Here, I present data from an observational field study in which I measured the effects of floral density on visitation to the annual composite Holocarpha virgata at both patch (4 m²) and site (12.6 ha) spatial scales. The species composition of flower visitors changed with floral density, and did so in different ways at the two scales. At the site scale, average floral density within patches of H. virgata or within patches of all summer-flowering species combined had a significant positive effect on per-flowerhead visitation by the long-horned bee Melissodes lupina and no significant effects on visitation by any other taxa. At the patch scale, per-flowerhead visitation by honeybees significantly increased whereas visitation by M. lupina often decreased with increasing floral density. For both species, responses to patch-scale floral density were strongest when site-scale floral density was high. The scale-dependence of flower visitor responses to floral density and the interactions between site- and patch-scale effects of floral density observed in this study underscore the importance of improving our understanding of pollinators’ responses to floral density at population scales.     

Allelopathic adaptation can cause competitive coexistence

The maintenance of plant diversity is often explained by the ecological and evolutionary consequences of resource competition. Recently, the importance of allelopathy for competitive interactions has been recognized. In spite of such interest in allelopathy, we have few theories for understanding how the allelopathy influences the ecological and evolutionary dynamics of competing species. Here, I study the coevolutionary dynamics of two competing species with allelopathy in an interspecific competition system, and show that adaptive trait dynamics can cause cyclic coexistence. In addition, very fast adaptation such as phenotypic plasticity is likely to stabilize the population cycles. The results suggest that adaptive changes in allelopathy can lead to cyclic coexistence of plant species even when their ecological characters are very similar and interspecific competition is stronger than intraspecific competition, which should destroy competitive coexistence in the absence of adaptation.     

模拟降雨量变化对黄河三角洲湿地植物群落特征的影响

气候变化背景下,降雨变化能够深刻影响河口湿地土壤水盐条件,而土壤水盐条件是影响植物群落特征的关键环境因子。本研究以黄河三角洲湿地植物群落为对象,依托野外降雨控制试验平台(减雨60%、减雨40%、自然对照、增雨40%、增雨60%),探讨了经过6年降雨处理后湿地植物群落特征对降雨量变化的响应及机制。结果表明: 随降雨量增加,土壤电导率显著降低,土壤湿度显著增大。降雨量变化影响了植物群落物种组成,增雨处理降低了碱蓬和盐地碱蓬的优势地位,提高了荻和白茅的优势地位。随降雨量增加,植物群落Shannon指数和Margalef丰富度指数显著提高。与对照相比,增减雨处理均降低了群落频度、多度和盖度,增雨60%处理群落频度显著降低54.9%,减雨60%、减雨40%、增雨40%、增雨60%处理群落多度分别显著降低38.9%、33.8%、35.8%和45.7%。随降雨量增加,植物群落地上生物量显著增加,但可能受淹水胁迫的影响,增雨60%处理地上生物量显著低于增雨40%。Margalef丰富度指数与地上生物量呈显著正相关;地上生物量、Shannon指数、Margalef丰富度指数、Simpson多样性指数均与土壤电导率呈显著负相关;地上生物量与土壤湿度呈显著正相关。降雨量变化通过改变黄河三角洲湿地土壤水盐条件显著影响了植物群落生长特征、物种组成和多样性。     

How the spatial scales of dispersal, competition, and environmental heterogeneity interact to affect coexistence

Spatial coexistence depends on a variety of biological and physical processes, and the relative scales of these processes may promote or suppress coexistence. We model plant competition in a spatially varying environment to show how shifting scales of dispersal, competition, and environmental heterogeneity affect coexistence. Spatial coexistence mechanisms are partitioned into three types: the storage effect, nonlinear competitive variance, and growth-density covariance. We first describe how the strength of each of these mechanisms depends on covariances between population densities and between population densities and the environment, and we then explain how changes in the scales of dispersal, competition, and environmental heterogeneity should affect these covariances. Our quantitative approach allows us to show how changes in the scales of biological and physical processes can shift the relative importance of different classes of spatial coexistence mechanisms and gives us a more complete understanding of how environmental heterogeneity can enable coexistence. For example, we show how environmental heterogeneity can promote coexistence even when competing species have identical responses to the environment.     

Negative plant–soil feedback and species coexistence

Different mechanisms, including equilibrium and non-equilibrium processes, have been taken into account as possible theoretical explanations of species coexistence. Despite the ample evidence on the existence of negative plant–soil feedback in both agriculture and natural vegetation, the role of these processes in the organization and dynamics of plant communities has so far been neglected. In this study, simulations by an individual-based competition model show how the intensity of negative feedback on individual plant performance can produce faster successional dynamics and allow species coexistence in two- and multi-species systems. The results show that even low levels of negative plant–soil feedback can enable species coexistence and often produce cyclic population dynamics. Moreover, the model highlights how negative feedback can generate positive reciprocal interspecific interactions at the population level, despite the fact that only competitive interactions is present between individual plants. In fact, competitive effects occur on a short-term scale, but positive reciprocal species interactions emerge only if negative feedback affects all species and if longer periods of simulation, more than the species life span, are considered. An important outcome of the model is the evidence that the effects at population level are timescale-dependent, thus showing the limitation of short-term species removal experiments used in traditional competition studies.     

Comparison of pollen transfer dynamics by multiple floral visitors: experiments with pollen and fluorescent dye

BACKGROUND AND AIMS: Most plant species are visited by a diversity of floral visitors. Pollen transfer of the four most common pollinating bee species and one nectar-robbing bee of the distylous plant Gelsemium sempervirens were compared. METHODS: Naturally occurring pollen loads carried by the common floral visitor species of G. sempervirens were compared. In addition, dyed pollen donor flowers and sequences of four emasculated recipient flowers in field cages were used to estimate pollen transfer, and the utility of fluorescent dye powder as an analogue for pollen transfer was determined. KEY RESULTS: Xylocopa virginica, Osmia lignaria and Habropoda laboriosa carried the most G. sempervirens pollen on their bodies, followed by Bombus bimaculatus and Apis mellifera. However, B. bimaculatus, O. lignaria and H. laboriosa transferred significantly more pollen than A. mellifera. Nectar-robbing X. virginica transferred the least pollen, even when visiting legitimately. Dye particles were strongly correlated with pollen grains on a stigma, and therefore provide a good analogue for pollen in this system. The ratio of pollen : dye across stigmas was not affected by bee species or interactions between bee species and floral morphology. However, dye transfer was more sensitive than pollen transfer to differences in floral morphology. CONCLUSIONS: The results from this study add to a growing body of literature highlighting that floral visitors vary in pollination effectiveness, and that visitors carrying the most pollen on their bodies may not always be the most efficient at depositing pollen on stigmas. Understanding the magnitude of variability in pollinator quality is one important factor for predicting how different pollinator taxa may influence the evolution of floral traits.     

Bee diversity on nectarful and nectarless honey mesquites

Nectar production has been proposed as an adaptation to attract pollinators that benefit from this resource. Energetic investments may be expensive, so some species such as Prosopis glandulosa have developed a dimorphic system of nectar production, which is expected to affect floral visitor behaviour and then plant fitness. We quantified bee diversity during a 2 year period in a population of the honey mesquite in order to determine changes in bee diversity due to the presence of nectar, bee preferences to collect either nectar of pollen, and to determine between year variations of bee faunas. Floral visitors were captured at three different times of the day during the flowering seasons of 1994 and 1995, in a population of Prosopis glandulosa which has a 1:1 proportion of nectar: nectarless individuals. Pollinators were clearly distinct between nectar morphs, bee species diversity and relative abundance of visits were significantly greater on nectarful than on nectarless plants, with species on nectarless individuals being a subset of those in the nectarful morph. Our results suggest differences in the function of floral rewards (i.e., nectar and pollen) to attract floral visitors. For the Chihuahuan arid environment, mesquite provides floral rewards with ease, quantity and quality for close to 10% of all bee fauna making them important components of these communities.     

Positive and negative biotic interactions and invasive Triadica sebifera tolerance to salinity: a cross‐continent comparative study

Exotic plant species may exhibit abiotic niche expansions that enable them to persist in a greater variety of habitat types in their introduced ranges than in their native ranges. This may reflect variation in limitation by different abiotic niche dimensions (realized niche shift) or phenotypic effects of biotic interactions that vary among ranges (realized niche expansion). Novel abiotic and biotic environments in the introduced range may also lead to genetic changes in exotic plant traits that enhance their abiotic stress tolerance (fundamental niche expansion). Here, we investigated how biotic interactions (aboveground herbivory and soil organisms) affect plant salinity tolerance using the invasive species Triadica sebifera from China (native range) and US (introduced range) populations grown in common gardens in both ranges. Simulated herbivory significantly reduced survival in saline treatments with reductions especially large at low salinity. Soil sterilization had a negative effect on survival at low salinity in China but had a positive effect on survival at low salinity in the US. Triadica survival and biomass were higher for US populations than for China populations, particularly in China but salinity tolerance did not depend on population origin. On average, arbuscular mycorrhizal (AM) colonization was higher for US populations, US soils and low salinity. These factors had a significant, positive, non‐additive interaction so that clipped seedlings from US populations in low saline US soils had high levels of AM colonization. Overall, our results show that phenotypic biotic interactions shape Triadica's salinity tolerance. Positive and negative biotic interactions together affected plant performance at intermediate stress levels. However, only aboveground damage consistently affected salinity tolerance, suggesting an important role for enemy release in expanding stress tolerance.     

Interactions between frequency and size of disturbance affect competitive outcomes

Disturbance has many effects on ecological communities, and it is often suggested that disturbance can affect species diversity by altering competitive outcomes. However, disturbance regimes have many distinct aspects that may act, and interact, to influence species diversity. While there are many theoretical models of disturbance-prone communities, few have specifically documented how interactions between different aspects of a disturbance regime change competitive outcomes. Here, we present a model of two plant species subject to disturbance which we then use to examine species coexistence over varying levels of two aspects of disturbance: frequency, and spatial extent (i.e., area disturbed). We show that the competitive outcome is affected differently by changes in each aspect and that the effect of disturbance frequency on species coexistence depends strongly on the spatial extent of the disturbance, and vice versa. We classify the nature of these interactions between disturbance frequency and extent on the basis of the shape of the resulting coexistence regions in a frequency?Cextent parameter plane. Our results illustrate that different types of interaction can result from differences in life-history traits that control species-specific sensitivity to frequency and extent of disturbance. Thus, our analysis shows that the various aspects of disturbance must be carefully considered in concert with the life-history traits of the community members in order to assess the consequences of disturbance.     

PLANT POLYPLOIDY AND POLLINATION: FLORAL TRAITS AND INSECT VISITS TO DIPLOID AND TETRAPLOID HEUCHERA GROSSULARIIFOLIA

In many polyploid species, polyploids often have different suites of floral traits and different flowering times than their diploid progenitor species. We hypothesized that such differences in floral traits in polyploids may subsequently affect their interactions with pollinating and other insect visitors. We measured floral morphology and flowering phenology in 14 populations of diploid and autotetraploid Heuchera grossulariifolia Rydb. (Saxifragaceae), determined if repeated evolution of independent polyploid lineages resulted in differentiation in floral morphology among those lineages, and ascertained if there was a consistent pattern of differentiation among genetically similar diploid and autotetraploid populations. In addition, we evaluated the differences in suites of floral visitors within a natural community where diploids and autotetraploids occur sympatrically. Overall, flowers of autotetraploid plants were larger and shaped differently than those of diploids, had a different flowering phenology than that of diploids, and attracted different suites of floral visitors. In comparison with flowers of diploids, tetraploid floral morphology varied widely from pronounced differences between cytotypes in some populations to similar flower shapes and sizes between ploidal levels in other populations. Observations of floral visitors to diploids and autotetraploids in a natural sympatric population demonstrated that the cytotypes had different suites of floral visitors and six of the 15 common visitors preferentially visited one ploidy more frequently. Moreover, we also found that floral morphology differed among independent autotetraploid origins, but there was no consistent pattern of differentiation between genetically similar diploid and autotetraploid populations. Hence, the results suggest that the process of polyploidization creates the potential for attraction of different suites of floral visitors. Multiple origins of polyploidy also presents the opportunity for new or different plant-insect interactions among independent polyploid lineages. These differences in turn may affect patterns of gene flow between diploids and polyploids and also among plants of independent polyploid origin. Polyploidy, therefore, may result in a geographic mosaic of interspecific interactions across a species' range, contributing to diversification in both plant and insect groups.     

Co-flowering neighbors influence the diversity and identity of pollinator groups visiting plant species

The generalization–specialization continuum exhibited in pollination interactions currently receives much attention. It is well-known that the pollinator assemblage of particular species varies temporally and spatially, and therefore the ecological generalization on pollinators may be a contextual attribute. However, the factors causing such variation and its ecological and evolutionary consequences are still poorly understood. This variation can be caused by spatial or temporal variation in the pollinator community, but also by variation in the plant community. Here, we examined how the floral neighbourhood influenced the generalization on pollinators and the composition of pollinators of six plant species differing in generalization levels and main pollinators. The diversity, identity and density of floral species affected both the level of generalization on pollinators and the composition of visitors of particular plant species. Although the relationships to floral neighbourhood varied considerably among species, generalization level and visitation by uncommon pollinators generally increased with floral diversity and richness. The generalization level of the neighbourhood was negatively related to the generalization level of the focal species in two species. The number of flowers of the pollinator-sharing species and the number of flowers of the focal species had different effects on the composition of visits in different species; attributable to differences in facilitation/competition for pollinator attraction. We propose that an important ecological implication of our results is that variation in species interactions caused by the pollination context may result in increased community stability. The main evolutionary implication of our results is that selection on flower and pollinator traits may depend, to an unknown extent, on the composition of the co-flowering plant community.     

Pollinator community structure and sources of spatial variation in plant–pollinator interactions in <Emphasis Type="Italic">Clarkia xantiana</Emphasis> ssp. <Emphasis Type="Italic">xantiana</Emphasis>

The structure of diverse floral visitor assemblages and the nature of spatial variation in plant–pollinator interactions have important consequences for floral evolution and reproductive interactions among pollinator-sharing plant species. In this study, I use surveys of floral visitor communities across the geographic range of Clarkia xantiana ssp. xantiana (hereafter C. x. xantiana) (Onagraceae) to examine the structure of visitor communities, the specificity of the pollination system, and the role of variation in the abiotic vs. biotic environment in contributing to spatial variation in pollinator abundance and community composition. Although the assemblage of bee visitors to C. x. xantiana is very diverse (49 species), few were regular visitors and likely to act as pollinators. Seventy-four percent of visitor species accounted for only 11% of total visitor abundance and 69% were collected in three or fewer plant populations (of ten). Of the few reliable visitors, Clarkia pollen specialist bees were the most frequent visitors, carried more Clarkia pollen compared to generalist foragers, and were less likely to harbor foreign pollen. Overall, the core group of pollinators was obscured by high numbers of incidental visitors that are unlikely to contribute to pollination. In a geographic context, the composition of specialist pollinator assemblages varied considerably along the abiotic gradient spanning the subspecies range. However, the overall abundance of specialist pollinators in plant populations was not influenced by the broad-scale abiotic gradient but strongly affected by local plant community associations. C. x. xantiana populations sympatric with pollinator-sharing congeners were visited twice as often by specialists compared to populations occurring alone. These positive indirect interactions among plant species may promote population persistence and species coexistence by enhancing individual reproductive success.Electronic Supplementary Material Supplementary material is available for this article at     

Importance,but not intensity of plant interactions relates to species diversity under the interplay of stress and disturbance

The lack of clarity on how the intensity and importance of plant interactions change under the co‐occurrence of stress and disturbance strongly impedes assessing the relative importance of plant interactions for species diversity. We addressed this issue in subalpine grasslands of the French Pyrenees. A natural soil moisture gradient further experimentally stretched at both ends was used and a mowing disturbance treatment was applied at each position along the soil moisture gradient. Changes in intensity and importance of plant interactions were assessed by a neighbour removal experiment using four target ecotypes. A structural equation modelling approach was used to assess the relative impact of stress, disturbance, the intensity and importance of plant interactions on diversity at both the neighbourhood and community scales. Without mowing, changes in intensity and importance of plant interactions only diverged in the dry part of the soil moisture gradient. The intensity of plant interactions linearly shifted from competition to facilitation with increasing stress, while the importance followed a hump‐shaped relationship. Species diversity components were tightly related to the importance of plant interactions only, both the neighbourhood and community scales. Mowing disturbance strongly reduced the importance of facilitation along the soil moisture gradient, and suppressed the relationship between the importance of plant interactions and diversity components. Together, our results highlight that 1) the importance is the best predictor of variations in species diversity in this subalpine herbaceous system, and 2) that fine‐scale processes such as plant interactions can affect the entire plant communities. Finally, our results suggest that high level of constraints due to co‐occurring stress and disturbance can inhibit the effects of plant interactions on species diversity, highlighting their potential role in regulating diversity and the maintenance/extinction of plant communities. Synthesis How plant interactions change along environmental gradients is an unsolved debate, particularly when both stress and disturbance interact. This lack of clarity explains why the relative impact of plant interactions (intensity and importance) on species diversity has been rarely assessed. Using an experimental approach, we found that the importance of plant interactions highly contributed to variation in species diversity, confirming that neighbourhood scale processes such as plant interactions can affect the entire plant communities. The co‐occurrence of stress and disturbance inhibited the effects of plant interactions, highlighting that plant interactions may regulate drops of diversity and the maintenance/extinction of plant communities.     

Are Trade-Offs Among Species’ Ecological Interactions Scale Dependent? A Test Using Pitcher-Plant Inquiline Species

Trade-offs among species' ecological interactions is a pervasive explanation for species coexistence. The traits associated with trade-offs are typically measured to mechanistically explain species coexistence at a single spatial scale. However, species potentially interact at multiple scales and this may be reflected in the traits among coexisting species. I quantified species' ecological traits associated with the trade-offs expected at both local (competitive ability and predator tolerance) and regional (competitive ability and colonization rate) community scales. The most common species (four protozoa and a rotifer) from the middle trophic level of a pitcher plant (Sarracenia purpurea) inquiline community were used to link species traits to previously observed patterns of species diversity and abundance. Traits associated with trade-offs (competitive ability, predator tolerance, and colonization rate) and other ecological traits (size, growth rate, and carrying capacity) were measured for each of the focal species. Traits were correlated with one another with a negative relationship indicative of a trade-off. Protozoan and rotifer species exhibited a negative relationship between competitive ability and predator tolerance, indicative of coexistence at the local community scale. There was no relationship between competitive ability and colonization rate. Size, growth rate, and carrying capacity were correlated with each other and the trade-off traits: Size was related to both competitive ability and predator tolerance, but growth rate and carrying capacity were correlated with predator tolerance. When partial correlations were conducted controlling for size, growth rate and carrying capacity, the trade-offs largely disappeared. These results imply that body size is the trait that provides the basis for ecological interactions and trade-offs. Altogether, this study showed that the examination of species' traits in the context of coexistence at different scales can contribute to our understanding of the mechanisms underlying community structure.     

Negative plant‐phyllosphere feedbacks in native Asteraceae hosts – a novel extension of the plant‐soil feedback framework

Over the past 25 years, the plant‐soil feedback (PSF) framework has catalyzed our understanding of how belowground microbiota impact plant fitness and species coexistence. Here, we apply a novel extension of this framework to microbiota associated with aboveground tissues, termed ‘plant‐phyllosphere feedback (PPFs)’. In parallel greenhouse experiments, rhizosphere and phyllosphere microbiota of con‐ and heterospecific hosts from four species were independently manipulated. In a third experiment, we tested the combined effects of soil and phyllosphere feedback under field conditions. We found that three of four species experienced weak negative PSF whereas, in contrast, all four species experienced strong negative PPFs. Field‐based feedback estimates were highly negative for all four species, though variable in magnitude. Our results suggest that phyllosphere microbiota, like rhizosphere microbiota, can potentially mediate plant species coexistence via negative feedbacks. Extension of the PSF framework to the phyllosphere is needed to more fully elucidate plant‐microbiota interactions.     

Linking aboveground and belowground diversity

Aboveground and belowground species interactions drive ecosystem properties at the local scale, but it is unclear how these relationships scale-up to regional and global scales. Here, we discuss our current knowledge of aboveground and belowground diversity links from a global to a local scale. Global diversity peaks towards the Equator for large, aboveground organisms, but not for small (mainly belowground) organisms, suggesting that there are size-related biodiversity gradients in global aboveground-belowground linkages. The generalization of aboveground-belowground diversity relationships, and their role in ecosystem functioning, requires surveys at scales that are relevant to the organisms and ecosystem properties. Habitat sizes and diversity gradients can differ significantly between aboveground and belowground organisms and between ecosystems. These gradients in biodiversity and plant community trait perception need to be acknowledged when studying aboveground-belowground biodiversity linkages.     

Legacy effects of aboveground-belowground interactions

Root herbivory can greatly affect the performance of aboveground insects via changes in plant chemistry. These interactions have been studied extensively in experiments where aboveground and belowground insects were feeding on the same plant. However, little is known about how aboveground and belowground organisms interact when they feed on plant individuals that grow after each other in the same soil. We show that feeding by aboveground and belowground insect herbivores on ragwort (Jacobaea vulgaris) plants exert unique soil legacy effects, via herbivore-induced changes in the composition of soil fungi. These changes in the soil biota induced by aboveground and belowground herbivores of preceding plants greatly influenced the pyrrolizidine alkaloid content, biomass and aboveground multitrophic interactions of succeeding plants. We conclude that plant-mediated interactions between aboveground and belowground insects are also important when they do not feed simultaneously on the same plant.     

Empirical and theoretical challenges in aboveground–belowground ecology

A growing body of evidence shows that aboveground and belowground communities and processes are intrinsically linked, and that feedbacks between these subsystems have important implications for community structure and ecosystem functioning. Almost all studies on this topic have been carried out from an empirical perspective and in specific ecological settings or contexts. Belowground interactions operate at different spatial and temporal scales. Due to the relatively low mobility and high survival of organisms in the soil, plants have longer lasting legacy effects belowground than aboveground. Our current challenge is to understand how aboveground–belowground biotic interactions operate across spatial and temporal scales, and how they depend on, as well as influence, the abiotic environment. Because empirical capacities are too limited to explore all possible combinations of interactions and environmental settings, we explore where and how they can be supported by theoretical approaches to develop testable predictions and to generalise empirical results. We review four key areas where a combined aboveground–belowground approach offers perspectives for enhancing ecological understanding, namely succession, agro-ecosystems, biological invasions and global change impacts on ecosystems. In plant succession, differences in scales between aboveground and belowground biota, as well as between species interactions and ecosystem processes, have important implications for the rate and direction of community change. Aboveground as well as belowground interactions either enhance or reduce rates of plant species replacement. Moreover, the outcomes of the interactions depend on abiotic conditions and plant life history characteristics, which may vary with successional position. We exemplify where translation of the current conceptual succession models into more predictive models can help targeting empirical studies and generalising their results. Then, we discuss how understanding succession may help to enhance managing arable crops, grasslands and invasive plants, as well as provide insights into the effects of global change on community re-organisation and ecosystem processes.