Coexistence Of Species Research Articles

Il progetto di paesaggio come teatro di coesistenza tra specie. Parc Martin-Luther-King a Parigi

Landscape architecture plays a crucial role in defining new paradigms for urban development, capable of implementing environmental quality and favouring biodiversity. In this sense, Parc Martin-Luther-King in Paris constitutes a sophisticated device with a high ecological value as well as a surprising catalyst of social aggregation, able of regenerating the urban area of Clichy-Batignolles. The articulate plant palette, the use of water in several forms and the application of differentiated management regimes help defining a collection of heterogeneous ecosystems where various forms of controlled interaction between human and non-human users are configured. The strong spatial dynamism and ecological variety favour the coexistence of different species, allowing the park to accommodate spaces for biodiversity alongside a rich functional programme.

The role of indirect interspecific effects in the stochastic dynamics of a simple trophic system.

Indirect interspecific effects (IIEs) occur when one species affects another through a third intermediary species. Understanding the role of IIEs in population dynamics is key for predicting community-level impacts of environmental change. Yet, empirically teasing apart IIEs from other interactions and population drivers has proven challenging and data-demanding, particularly in species-rich communities. We used stochastic population models parameterized with long-term time series of individual data to simulate population trajectories and examine IIEs in a simple high-arctic vertebrate food chain consisting of the wild Svalbard reindeer, its scavenger (the Arctic fox) and the barnacle goose, a migratory prey of the fox. We used the simulated population trajectories to explore co-fluctuations between the species within the food chain. Additionally, we adjusted the model in two ways: first, to isolate the impact of fluctuations in the abundance of a species by keeping its abundance constant; and second, to isolate the impact of a trophic interaction on the dynamics of other species by setting the abundance of the influencing species to zero. We found that fluctuations in reindeer carcasses shaped fox abundance fluctuations, which subsequently affected goose population dynamics. Reindeer and goose population growth rates were nevertheless only weakly correlated, probably in part due to demographic and environmental stochasticity, density dependence and lagged dynamics in the geese. However, removing the fluctuations in reindeer abundance or setting reindeer abundance to zero indeed demonstrated strong underlying IIEs on goose population dynamics and extinction probability. This study thus highlights the importance of species interactions, including IIEs, on species coexistence and communities in the long-term, that is beyond immediate effects and covariation in short-term fluctuations.

Unraveling key environmental drivers of spatial variation in plant functional traits: Insights from Dacrydium pectinatum de Laub. in natural communities on Hainan Island, China

Accurate predictions of species distribution and coexistence in response to environmental changes depend on a thorough understanding of how functional traits relate to environmental conditions. However, there is still limited evidence regarding the sources of functional trait variation and the environmental mechanisms that regulate these traits in tropical forests. This study focuses on Dacrydium pectinatum de Laub., a crucial and endangered species native to the tropical mountain forests of Hainan Island, China. We gathered functional trait data from 68 permanent plots of D. pectinatum situated in three regions: Bawangling (163 tree species), Diaoluoshan (127 tree species), and Jianfengling (175 tree species). Nine functional traits were measured at the species level, and their variation patterns and sources were analyzed using linear mixed-effects models and variance decomposition methods. Our findings reveal that environmental pressures cause variations in trait relationships across different site conditions at the species level. Typically, inter-specific trait variation exceeds intra-specific variation, particularly for leaf area (LA) and specific leaf area (SLA). This indicates that trait variability is influenced by how species adapt to and balance specific environmental conditions. Site conditions significantly impact trait variation, especially for SLA, leaf dry matter content (LDMC), and wood density (WD). Additionally, intraspecific variation is notable for certain traits, reflecting individual responses to environmental heterogeneity. At the community level, eight out of nine traits exhibit significant changes in community-weighted mean (CWM) across various site conditions and environmental gradients. For instance, LA's CWM increases with soil fertility, whereas SLA, leaf nitrogen content (LNC), and leaf phosphorus content (LPC) show differences between site conditions. LDMC and WD decrease significantly in high-fertility environments, suggesting a transition from resource conservation to resource acquisition strategies within communities as soil fertility rises. Geographic variables play a crucial role in trait distributions across different community levels, with elevation and soil factors also contributing significantly to trait variation. Overall, our study provides direct evidence of how environmental filtering influences plant functional trait distributions and community assembly. Future research should explore the mechanisms driving these trait-environment relationships and their responses across various ecological contexts.

Landscape and environmental heterogeneity support coexistence in competitive metacommunities

Metapopulation models have been instrumental in quantifying the ecological impact of landscape structure on the survival of a focal species. However, extensions to multiple species with arbitrary dispersal networks often rely on phenomenological assumptions that inevitably limit their scope. Here, we propose a multilayer network model of competitive dispersing metacommunities to investigate how spatially structured environments impact species coexistence and ecosystem stability. We introduce the concept of landscape-mediated fitness, quantifying how fit a species is in a given environment in terms of colonization and extinction. We show that, when all environments are equivalent, one species excludes all the others-except the marginal case where species fitnesses are in exact trade-off. However, we prove that stable coexistence becomes possible in sufficiently heterogeneous environments by introducing spatial disorder in the model and solving it exactly in the mean-field limit. Crucially, coexistence is supported by the spontaneous localization of species through the emergence of ecological niches. We show that our results remain qualitatively valid in arbitrary dispersal networks, where topological features can improve species coexistence by buffering competition. Finally, we employ our model to study how correlated heterogeneity promotes spatial ecological patterns in realistic terrestrial and riverine landscapes. Our work provides a framework to understand how landscape structure enables coexistence in metacommunities by acting as the substrate for ecological interactions.

Specificity determinants of pathogens in forest

Abstract Host‐specific pathogens have long been suggested to act as a major driver of species diversity in tropical forests. However, determining the degree of host specificity of potential pathogens coupled to key cellular characteristics of infection is difficult and time‐consuming. These challenges have delayed progress in relating the functional specificity of pathogenic fungi to ecological consequences. We tested the pathogenicity of 27 (of 215) fungi that were isolated from surface sterilized roots of seedlings from four common tree species in a diverse subtropical forest. Inoculation experiments showed that six fungi exhibited strong pathogenicity on the host seedlings. Five of these only infected their specific hosts (i.e. host‐specific pathogen species). Green fluorescent protein labelling revealed that in three host‐specific pathogens fungal hyphae were able to grow into the vascular tissues only in their specific host plant, in contrast to other fungal‐host combinations that exhibit non‐pathogenic interactions. This fluorescent labelling technique allows direct tracking of the progress of fungal infection in different host tissues. Synthesis. By coupling the green fluorescent protein technique with standard host inoculation experiments, we determined the developmental differences between infections by pathogenic and non‐pathogenic fungi in a relatively simple and straightforward way. Our work provides a useful tool for rapidly screening and categorizing host–fungal interactions, reflecting the functional basis of host specificity of pathogenic fungi. More broadly, this technique can contribute to understanding the roles of pathogens in species coexistence and biodiversity maintenance in forest communities.

Experimental species removal reveals species contributions to positive pollinator-mediated reproductive interactions.

Pollinator-mediated reproductive interactions among co-flowering plant species provide a canonical example of how biotic factors may contribute to species coexistence, yet we lack understanding of the exact mechanisms. Flowering-dominant and unusually attractive "magnet species" with disproportionate contributions to pollination may play key roles in such reproductive interactions, but their relative roles within the same community have rarely been assessed. We experimentally removed either a flowering-dominant or a highly attractive magnet species and compared effects on visitation frequency, pollinator richness, and seed set of co-flowering plants. Removal of either the flowering-dominant species or the magnet species reduced community-level pollinator visitation. Removal of the magnet species had the most consistent effect, including reduced pollinator visitation and richness, and reduced seed set of most co-flowering plants. These results suggest that the magnet species, which interacts with a wider range of pollinator species than does the dominant species, promotes the visitation and reproductive fitness of most other species. Removal of the flowering-dominant species affected only certain species, perhaps because these plants had floral traits similar to the dominant species. Our results highlight the role of attractive magnet species within a community in structuring reproductive interactions and identify potential mechanisms involved in coexistence facilitated by reproductive interactions.

Coexistence and food sources of adult mosquitoes (Diptera: Culicidae) in a rural health center in Piura, Peru 2024.

Motivation for the study. Rural health facilities could be potential foci of transmission and scenarios of zoonosis during epidemic outbreaks of dengue and other arbovirosis due to the coexistence of mosquito species that feed on different vertebrates. Main findings. Aedes aegypti feeds on Homo sapiens sapiens. Culex quinquefasciatus feeds on Homo sapiens sapiens and Canis familiaris. Both coexist in health care areas of the Querecotillo health center. Implications. Molecular techniques should be integrated into vector control to understand feeding patterns in natural conditions and information on probable reservoirs. This study aimed to determine the coexistence and food sources of adult mosquitoes (Diptera: Culicidae) in a rural health center in Piura, Peru by using a descriptive cross-sectional design. Entomological techniques were used to capture and identify mosquitoes, and molecular biotechnology techniques were used to identify food sources. A total of 793 specimens of the Culex and Aedes genera were found coexisting, 789 (99.5%) were Culex quinquefasciatus, 607 (76.9%) were males and 182 (23.1%) were females. Likewise, 4 (100%) corresponded to Aedes aegypti females. The food sources of Aedes aegypti were Homo sapiens sapiens, and Homo sapiens sapiens and Canis familiaris were the food sources of Culex quinquefasciatus. This study provides evidence that rural health centers could be acting as foci of arbovirosis, with the risk that people who come for different ailments could contract diseases transmitted by C. quinquefasciatus and A. aegypti.

A new dimension of leaf economic spectrum: temporal instability of relationships among genotypes.

Leaf economic spectrum (LES) relationships have been studied across many different plant lineages and at different organizational scales. However, the temporal stability of the LES relationships is largely unknown. We used the wild blueberry system with high genotypic diversity to test whether trait-trait relationships across genotypes demonstrate the same LES relationships found in the global database (GLOPNET) and whether they are stable across years. We studied leaf structure, photosynthesis, and leaf nutrients for 16 genotypes of two wild blueberry species semi-naturally grown in a common farm in Maine, USA, across 4 yr. We found substantial variation in leaf structure, physiology, and nutrient traits within and among genotypes, as well as across years in wild blueberries. The LES trait-trait relationships (covariance structure) across genotypes were not always found in all years. The trait syndrome of wild blueberries was shifted by changing environmental conditions over the years. Additionally, traits in 1 yr cannot be used to predict those of another year. Our findings show that LES generally holds among genotypes but is temporally unstable, stressing the significant influence of trait plasticity in response to fluctuating environmental conditions across years, and the importance of temporal dimensions in shaping functional traits and species coexistence.

Interspecific interactions among major carnivores in Panna Tiger Reserve: A multispecies occupancy approach

AbstractLarge carnivores play a crucial role in trophic cascades, affecting the population dynamics of both co‐predators and prey within an ecosystem. Understanding the significance of these carnivores in trophic interactions is essential for developing effective conservation and management strategies. We examined the effects of occupancy dynamics and patterns of species interactions and coexistence within the carnivore guild in the Panna Tiger Reserve in India. We collected camera trap data (two seasons, 2019) in a presence–absence framework and applied multispecies occupancy models to assess the occupancy, co‐occurrence, and interactions among species. We also examined activity overlap to understand the temporal segregation in the carnivore guild. The mean marginal occupancy was highest for leopards in winter (Ψwinter 0.92 ± 0.02, Ψsummer 0.63 ± 0.05) and hyenas in summer (Ψsummer 0.93 ± 0.03, Ψwinter 0.78 ± 0.03) and was lowest for tigers in both seasons (Ψwinter 0.62 ± 0.05, Ψsummer 0.15 ± 0.05). Co‐occurrence probability among carnivores was higher in winter than in summer, and conditional occupancy was consistently higher when other species were present. Different environmental factors influenced marginal occupancy and co‐occurrence patterns across seasons. Strong temporal overlaps were recorded between tiger–leopard (0.87–0.91) and tiger–hyena (0.78–0.79). We detected a significant spatial segregation between tigers and leopards, as they prefer different habitat types in different seasons, along with high temporal overlap. Resource availability strongly governs the association of carnivores with their habitat selection. Hyenas demonstrated higher dependency on tigers than on leopards for resources. These findings indicate that coexistence with apex‐predator species is feasible through strategic adaptation to fulfill resource requisition.

Can adaptive prey refuge facilitate species coexistence in Bazykin’s prey–predator model?

Bazykin’s prey–predator system with constant and adaptive prey refuge is investigated in this paper. We examine Bazykin’s resource consumer system with exponential growth rate and by employing constant prey refuge we demonstrate that refuge does promote species coexistence. The incorporation of constant prey refuge expands the stability zone for the interior equilibrium. Furthermore, the bifurcation diagram with reference to prey refuge (ur) shows how ur influences the system’s behavior from unstable to periodic stability and then to equilibrium stability. Next, we provide a Bazykin’s model with adaptive prey refuge and develop a fitness function for the prey population using refuge as a strategy and in order to obtain the prey’s optimal response to the environment we determine evolutionary stable strategies (ESS). Our model consists of more than one ESS, thus we employ the best response dynamics for the prey strategy. Our analysis showcases that adaptive refuge used by the prey population promotes the coexistence of prey–predator dynamics. Our theoretical analysis is supported by extensive numerical simulations. Bifurcation diagrams with reference to the two most crucial parameters, namely, δ2 (intra-species competition rate among predators) and τ (the rate at which populations adapt to their environment), are included in the numerical analysis. Species cohabitation along a limit cycle or at an equilibrium is discovered to be dependent on the pace of strategy dynamics and the competition amongst predator species.

Effects of expansion of protected areas and habitat transformation on spatiotemporal variation in human-wildlife conflict.

Land-use changes and the expansion of protected areas (PAs) have fostered increased interactions between humans and wildlife, resulting in an escalation of human-wildlife conflict (HWC) globally. However, HWC spatiotemporal pattern variation and its associations with PAs and land-use change remain poorly understood. To address this knowledge gap, we mapped and analyzed HWCs from 1990 to 2022 across China. We comprehensively mapped the spatiotemporal dynamics of HWCs in ArcGIS with data sets stratified by county, year, and species; assessed the impact of PAs through propensity score matching; and analyzed the effects of habitat transformation with linear mixed models. As PA increased from 0 to 20,000km2, the likelihood of HWCs initially increased (50%) before declining (20%). Conversely, as the distance from a PA grew, the likelihood of HWC gradually decreased (0 beyond 65km). There was a temporal lag between the establishment of a PA and the occurrence of HWC. Habitat loss catalyzed HWCs, whereas decreased levels of habitat fragmentation sometimes initially caused a temporary increase in HWCs. In general, the distribution of PAs greatly affected HWC occurrence, and habitat loss and fragmentation were critical drivers of HWCs, both of which exhibited time-lagged effects. HWC has become more challenging to address as conservation initiatives have led to significant recovery of the habitats and populations of wild animals. Further measures to address the HWCs are needed to ensure the preservation of animal welfare while fostering the mutually beneficial coexistence of humans and animal species. Finally, our study provides an important starting point for informing future HWC research and conservation planning on a global scale.

Floral morphology and pollen placement strategies of bat-pollinated flowers: a comparative analysis within a guild of chiropterophilous plants in a neotropical dry forest

BackgroundSynchronopatric plant species, coexisting and flowering simultaneously, often engage in intense competition for pollen deposition on shared pollinators. This study focuses on the intricate dynamics of chiropterophilous flowers within the neotropical bat-pollination plant guild, specifically investigating the mechanical fit of reproductive structures to pollinating bats at the community level.MethodsUtilizing a diverse guild of bat-pollinated plant species from the Caatinga, the largest dry forest in the Neotropics, our research integrates various key components. Initially, we identified specific contact sites for floral reproductive structures on the bat's body, exploring diverse pollen placement strategies. Subsequent efforts involved characterizing floral traits within the guild and examining their associations with different pollen placement strategies. Precision in the contact of floral reproductive structures was estimated, and findings were integrated by associating pollen placement strategies and precision with the investment in pollen production.ResultsWe found that certain bat body parts, particularly the face and neck, were more frequently contacted by reproductive structures. The three identified categories of pollen placement strategies were evenly distributed among plant species, each linked to specific floral traits. Notably, the absence of oriented herkogamy prevailed in 70% of the species. Morphometric analyses unveiled significant variations in operative distances among species, emphasizing exceptional variability in certain outliers. While precision in pollen transfer was influenced by key factors, surprisingly, investment in pollen production did not differ among plants with distinct pollen placement strategies. Furthermore, it showed no correlation with fundamental accuracy.ConclusionsThe subsequent exploration delves into the intricate associations between distinct floral characteristics and various pollen placement strategies, shaping the complex pollen landscape on bat bodies. This research provides valuable insights into the community-level dynamics of chiropterophilous flowers in the Caatinga Dry Forest, emphasizing the role of different pollen deposition strategies in facilitating the coexistence of multiple plant species within the chiropterophilous guild.

It's about (taking up) space: Discreteness of individuals and the strength of spatial coexistence mechanisms.

One strand of modern coexistence theory (MCT) partitions invader growth rates (IGR) to quantify how different mechanisms contribute to species coexistence, highlighting fluctuation-dependent mechanisms. A general conclusion from the classical analytic MCT theory is that coexistence mechanisms relying on temporal variation (such as the temporal storage effect) are generally less effective at promoting coexistence than mechanisms relying on spatial or spatiotemporal variation (primarily growth-density covariance). However, the analytic theory assumes continuous population density, and IGRs are calculated for infinitesimally rare invaders that have infinite time to find their preferred habitat and regrow, without ever experiencing intraspecific competition. Here we ask if the disparity between spatial and temporal mechanisms persists when individuals are, instead, discrete and occupy finite amounts of space. We present a simulation-based approach to quantifying IGRs in this situation, building on our previous approach for spatially non-varying habitats. As expected, we found that spatial mechanisms are weakened; unexpectedly, the contribution to IGR from growth-density covariance could even become negative, opposing coexistence. We also found shifts in which demographic parameters had the largest effect on the strength of spatial coexistence mechanisms. Our substantive conclusions are statements about one model, across parameter ranges that we subjectively considered realistic. Using the methods developed here, effects of individual discreteness should be explored theoretically across a broader range of conditions, and in models parameterized from empirical data on real communities.

Quercus acutissima exhibits more adaptable water uptake patterns in response to seasonal changes compared to Pinus massoniana

BackgroundSeasonal precipitation variability significantly affects water use in forests; however, whether water uptake is adapted to changes in precipitation, particularly whether it could affect the coexistence of tree species, has rarely been quantified in forest systems. MethodIn this study, dual stable isotopes and the Li-6400 portable photosynthesis system were used to determine the water sources of a mixed conifer (Pinus massoniana) and broadleaf (Quercus acutissima) forest and changes in hydraulic characteristics during the dry and wet seasons in a southern hilly region of China. ResultsAlthough the hydraulic characteristics of P. massoniana were lower than those of Q. acutissima, it maintained a stable water source from the deep soil layer and a higher stomatal conductance (Gs), leading to a higher transpiration rate (Tr) during the growing seasons. Q. acutissima mainly absorbed water from deeper soil layers in the dry season and took up from shallow soil layers in the wet season. Its Gs values exhibited sensitivity to precipitation, while it maintained a lower Tr value during the growing seasons. The excessive water-use strategy observed in P. massoniana may confer weak drought-tolerance during higher frequency and more intense extreme precipitation events, whereas Q. acutissima may exhibit better ecological adaption to precipitation changes. ConclusionsThe overlap of water niches in mixed forests did not appear to affect the coexistence of tree species. The present study provides insights into reforestation and water management in the southern hilly regions of China.

Maxent modelling reveals suitable habitat remains unchanged for Carcinus maenas in Australia

ABSTRACT This study assesses the habitat suitability of the invasive green crab, Carcinus maenas, in Australia using MaxEnt modelling under current and future climate scenarios. The species has significant ecological impacts, displacing native species and altering habitats. Using 90 occurrence points from the Global Biodiversity Information Facility, the MaxEnt model shows high performance (Area Under the Curve value of 0.99), indicating reliable predictions. Currently, the green crab's habitat suitability along the Australian coast ranges from high to medium in Tasmania, Victoria, New South Wales and South Australia and low in Western Australia and South Queensland. Future projections suggest a decrease in suitable habitats, confined to Tasmania, Victoria, Adelaide and New South Wales. These findings can guide the development of long-term management and conservation plans for C. maenas, with an emphasis on areas with consistent habitat suitability. Additionally, further field and laboratory experiments are recommended to understand the species’ tolerance to environmental changes. Recognising the ecological impact of C. maenas is crucial for informed decision-making to preserve Australia's ecosystems and ensure the sustainable coexistence of native species amidst invasive threats.

Fluctuation-dependent coexistence of stage-structured species

Fluctuation-dependent coexistence of stage-structured species

Metabolic interactions shape emergent biofilm structures in a conceptual model of gut mucosal bacterial communities

The gut microbiome plays a major role in human health; however, little is known about the structural arrangement of microbes and factors governing their distribution. In this work, we present an in silico agent-based model (ABM) to conceptually simulate the dynamics of gut mucosal bacterial communities. We explored how various types of metabolic interactions, including competition, neutralism, commensalism, and mutualism, affect community structure, through nutrient consumption and metabolite exchange. Results showed that, across scenarios with different initial species abundances, cross-feeding promotes species coexistence. Morphologically, competition and neutralism resulted in segregation, while mutualism and commensalism fostered high intermixing. In addition, cooperative relations resulted in community properties with little sensitivity to the selective uptake of metabolites produced by the host. Moreover, metabolic interactions strongly influenced colonization success following the invasion of newcomer species. These results provide important insights into the utility of ABM in deciphering complex microbiome patterns.

Challenges and opportunities when studying movement ecology in science and practical conservation

Movement is a key mechanism influencing biodiversity patterns and ecosystem processes. Movement ecology science aims to understand the causal relationships between environmental conditions, animal movements, interactions and coexistence of species, as well as effects of movement patterns on ecosystem processes. In contrast, practical conservation primarily aims to understand organisms' movements to improve species management, protection, legal monitoring or risk assessment, and species-habitat interactions. Despite the many studies of movement ecology in basic and applied sciences as well as in practical conservation in terrestrial ecosystems, knowledge gain and transfer between disciplines are limited. Better integration and linking of both disciplines would result in diverse science-practice synergies, but these are currently constrained by numerous challenges that need to be overcome. From a scientific perspective, knowledge gain from practice is limited by multitude of case studies with limited spatial and temporal resolution. This can be overcome by improving access and combining the diversity of data for a research area that often deals with small sample sizes. From a practical perspective, the movement ecology framework which is often dedicated to basic research, and access and language barriers of scientific publications limit the application of scientific results in practice. Here movement ecologists should be encouraged to consider conservation issues more frequently in addition to basic research. The transfer of scientific results could be improved by scientists providing sufficient details for practitioners to extract relevant information and publish at least an open-access abstract in local language with clear management recommendations. Further, the use of open-access repositories allows both, scientists and practitioners an overview of the multitude of studies and helps to share data in order to derive general conclusions. Challenges impacting science and practice can be conceptual, organisational and technical in nature. Such constrains can be overcome, for example, by providing verified trapping protocols, using recent technological developments and analytical methods combined with trainings on these state-of-the-art tracking and analysing tools. In particular, collaborative project planning between scientists and practitioners can help to improve the sampling design of applied studies and broaden the data base for science in order to significantly advance the movement ecology framework and gain comprehensive knowledge for practical conservation.

Regional and local patterns of soil arthropod diversity are explained by different processes in southwest China

Understanding the distribution patterns and underlying mechanisms of community assembly at different spatial scales is crucial for the ecology and conservation of organisms, yet little is known about soil arthropods. In this study, we tested the relative importance of the two hypotheses that could explain soil arthropod distribution patterns at local and regional scales: (1) the habitat heterogeneity hypothesis (spatial complexity and variability of a habitat allow the coexistence of many species), and (2) the more-individuals hypothesis (the amount of resources per se, regardless of its spatial heterogeneity, increases overall soil arthropod abundance and richness). We extensively collected soil arthropods (identified to families or subfamilies) and measured soil physicochemical properties in four forests distributed across latitudes in Yunnan Province, China. We found that soil arthropod abundance and taxon richness increased with increasing latitudes, contrasting with the generally known pattern for plants and aboveground animals. Litter biomass (resources) explained the taxon richness and abundance at the regional scale, which aligned with the more-individuals hypothesis. Other soil physicochemical properties (e.g., Ca, TP, Mg, Mn, and pH) were more important at the local scale, underpinning the habitat heterogeneity hypothesis. However, the relative importance of individual soil properties was highly location-specific, suggesting that the environmental factors operating in one location do not necessarily reflect those operating in others at different latitudes. These findings improve our understanding of the community assembly and ecological processes of soil arthropods at different spatial scales, which is vital for predicting the future of soil biodiversity.

Increased soil bacteria-fungus interactions promote soil nutrient availability, plant growth, and coexistence

Tree species and interkingdom relationships in the belowground metacommunity are key factors in determining soil microbial diversity and community composition. However, how bacterial-fungal interactions mediate soil nutrient and plant growth remains largely unexplored in the coniferous forests. Here, we selected three types of naturally growing coniferous forests on the Loess Plateau—pure stands of Platycladus orientalis, mixed stands of Platycladus orientalis and Pinus tabuliformis, and pure stands of Pinus tabuliformis—to compare the differences in soil properties, microbial diversity and community composition, soil enzymatic activity, and plant growth conditions across these stand types. We found that tree species mixing significantly alters soil microbial community diversity and composition, increasing the positive associations between bacteria and fungi. Compared to pure stands, mixed stands exhibit significantly higher bacterial diversity, whereas fungal diversity shows no significant difference. Additionally, available soil nutrients (ammonium nitrogen and available phosphorus) are significantly increased in mixed stands, along with their associated soil enzymatic activities. The partial least squares path model suggests that higher bacterial diversity enhances bacterial-fungal positive interactions, increasing the relative abundance of ectomycorrhizal fungi and the decomposition rate of organic matter in mixed stands, thereby boosting soil nutrient availability and plant growth. These results highlight the importance of positive bacterial-fungal associations for soil nutrient availability and plant growth, deepen the understanding of the role of soil microbial interactions in mediating plant species coexistence. Most importantly, our results implied a stable coexistence of the pioneer P. orientalis and the late successional species P. tabuliformis in the Loess Plateau region and provided a microbiological interpretation.