Exploring how biodiversity influences forest biomass is critical to biodiversity-ecosystem functioning (BEF) research. However, the combined effects of species diversity and compositional heterogeneity among communities and spatial scale on aboveground biomass (AGB) remain insufficiently resolved. We quantified species alpha diversity, beta diversity, and AGB in 15 one-hectare permanent forest plots representing five forest community types across three spatial scales (10 m, 20 m, 50 m) in eastern China, then analyzed the relationships between diversity and AGB. The results showed that positive relationships between alpha diversity and aboveground biomass were consistently observed in evergreen broad-leaved forests and low-elevation evergreen and deciduous broad-leaved mixed forests, and these relationships generally became stronger with increasing spatial scale in these forest types. In contrast, high-elevation mixed forests exhibited weak or negative associations between alpha diversity and biomass. For beta diversity, significant positive associations with biomass differences were detected at the 10 m scale across all forest communities. At 20 m scale, these relationships remained predominantly positive but were less uniform among community types, with some variation in direction and strength. At 50 m scale, the relationships weakened and became more variable among communities, showing a mixture of positive, negative, and non-significant patterns depending on forest type. Collectively, our findings highlight that incorporating spatial scale and forest type is essential for interpreting biodiversity-biomass relationships, and conserving both local species diversity and compositional heterogeneity is very important for sustaining forest productivity, carbon storage, and ecosystem stability.

Density dependence, both conspecific and heterospecific, is widely recognized as a crucial driver of plant species diversity. However, treating multiple heterospecific species as a homogeneous group obviously overlooks the variability in the impacts of different heterospecific neighbors on the survival or growth of focal species. In this study, we developed the Static-Dynamic Coupled Interspecific Association Classification Framework (SDIACF), which categorizes heterospecific neighbors based on their positive/negative interspecific associations and dynamic changes with focal species. We further used generalized linear mixed-effect models to analyze how conspecific and various heterospecific neighbors classified by the above framework influenced the survival and growth rates of the focal species. Our results revealed that heterospecific neighbors, deconstructed using SDIACF, exerted distinct effects on the focal species. Specifically, regardless of their initial interspecific association with the focal species, heterospecific neighbors with more negative associations showed a negative impact on the focal species, while those with more positive associations showed a positive effect. However, among heterospecific neighbors exhibiting identical dynamic interspecific associations, positively associated neighbors were slightly more conducive to the survival of the focal species than negatively associated ones, but slightly detrimental to its growth. In summary, our results demonstrate that heterospecific neighbors are not a homogeneous entity but play important and complex roles in species coexistence. The development of SDIACF not only constitutes a significant supplement to traditional density dependence research but also offers a novel perspective for further exploring species coexistence. In this study, we developed the Static-Dynamic Coupled Interspecific Association Classification Framework (SDIACF), which categorizes heterospecific neighbors based on their positive/negative interspecific associations and dynamic changes with focal species. Through SDIACF, heterospecific neighbors can be classified into distinct categories: dominant competitors, symmetric competitors, potential mutualists, and synergistic mutualists, each with distinct effects on the focal species. The development of SDIACF breaks the previous convention of analyzing heterospecific neighbors solely as a whole. Not only does it refine our understanding of the mechanisms underlying heterospecific neighbor effects, but it also extends and innovates upon the traditional density dependence theoretical framework. (sic)(sic):(sic)(sic)(sic)(sic)((sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic))(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic);(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic):(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(SDIACF)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

Abstract Different mycorrhizal types in plants exhibit distinct strategies for resource acquisition and environmental adaptation. Elevation integrates multiple environmental factors and influences community structure and species diversity in mountain ecosystems. However, how tree species with different mycorrhizal types vary in diversity-elevation patterns remains poorly understood. A 3210 m continuous elevational transect (636–1928 m a.s.l.) was established in Baishanzu National Park, China, and we surveyed adult trees and saplings of three mycorrhizal types: arbuscular mycorrhizal (AM), ectomycorrhizal (EcM), and ericoid mycorrhizal (ErM). We calculated Hill indices (q = 0, 1, 2) to compare diversity-elevation patterns among mycorrhizal types and life stages. Bray-Curtis and Sørensen indices were used to quantify elevational changes in species composition dissimilarity between adults and saplings. Results showed that AM trees consistently exhibited higher species diversity than EcM and ErM trees. Elevation was the primary driver of diversity across all mycorrhizal types. AM diversity showed a hump-shaped relationship with elevation, whereas EcM and ErM declined monotonically with increasing elevation. Across all mycorrhizal types, adults showed a consistent hump-shaped elevation pattern, while saplings shifted from hump-shaped to monotonically decreasing patterns as q increased with abundant species weighted. Species composition dissimilarity between adults and saplings increased with elevation for AM trees, declined for EcM trees, and showed an inverse hump-shaped pattern for ErM trees. Overall, our findings reveal elevational diversity trajectories and regeneration dynamics among mycorrhizal types, highlighting the crucial role of mycorrhizal associations in shaping diversity-elevation relationships by mediating species abundance and regeneration across life stages in mountainous forests.

Habitat fragmentation is associated with decreased species diversity. However, the effects of fragmentation on the processes that maintain diversity, such as enemy‐mediated negative conspecific density dependence (CDD), are largely unknown. We examined how negative CDD in seedling survival is influenced by habitat fragmentation. We measured the effect of conspecific density on seedling survival of 30 species for 10 years on 25 islands in an artificially fragmented habitat and took parallel measurements of the potential drivers: soil physical and chemical properties, and insect herbivore communities. Increasing densities of conspecific trees and seedlings reduced seedling survival more on larger and more isolated islands. These processes were linked to increases in insect herbivore richness on larger islands, and less fertile soils on more isolated islands. Synthesis. Our results indicate that shifts in the abiotic and biotic conditions of fragmented habitats can modify the mechanisms thought to maintain species coexistence, perhaps contributing to the long‐term decay of fragmented ecosystems, and suggesting approaches for restoration. The relationships between island configuration, and insect herbivore communities and soil properties may vary among ecosystems, which could help explain variation among studies in the effects of fragmentation on biodiversity.

Climate change is compelling species to seek refuge at higher elevations and latitudes. While researchers commonly study these migrations using discontinuous elevational transects, this methodology may introduce significant biases into our understanding of species movement. These potential biases could lead to flawed biodiversity conservation policies if left unexamined. To address this concern, we utilized species distribution data from a novel continuous elevational transect to evaluate the accuracy of discontinuous transect methods. Our analysis focused on how quadrat spacing and survey time intervals affect bias in estimating species range shifts. The results were striking: the widely used settings for discontinuous transects failed to detect 7.2% of species, inaccurately estimated shift distances for 78% of species, and produced an overall error rate of 86%. Wider quadrat spacing increased these error rates, while longer survey intervals generally reduced them. Moreover, discontinuous transects consistently underestimated species shift distances, with this underestimation becoming more pronounced over longer survey periods. Our pioneering assessment of bias in discontinuous elevational transects demonstrates that a 50 m quadrat spacing combined with a 60-year survey interval optimizes monitoring species range shifts for conservation planning. This baseline protocol could be further strengthened through supplementary, frequent surveys targeting high-elevation species—a strategic approach that maximizes accuracy while maintaining cost-effectiveness.

Habitat loss significantly threatens global biodiversity and ecosystem functionality. Forest biomass, encompassing both aboveground and belowground, is key indicator of ecosystem functioning. However, the effects of habitat loss on belowground biomass and the factors driving its distribution in fragmented habitats remain unclear. We conducted a field planting experiment involving four woody plant species with distinct functional traits (e.g., shade-tolerance and dominance) across edge and interior regions of 11 islands within a subtropical anthropogenic archipelago in China. Belowground biomass accumulation was measured in the growth areas of each species, including root biomass of the planted species and other plants. We then tested the effects of island area, edge effects, and abiotic variables (e.g., soil physicochemical properties and topographic attributes) on belowground biomass. Our results demonstrate that mean belowground biomass increases significantly as island area decreases below a certain threshold. Altitude, litter layer depth, soil bulk density, and soil depth significantly affect belowground biomass. Specifically, belowground biomass accumulation in the growth areas of shade-intolerant species increases significantly as island area decreases before certain threshold. Additionally, mean belowground biomass in edge habitats was significantly greater than in interior habitats, particularly in the growth areas around dominant and shade-intolerant species. These findings suggest that habitat size along with soil physical properties, edge effects, and the species shade tolerance play a critical role in shaping belowground biomass accumulation in fragmented landscapes. This study underscores the importance of integrating belowground biomass dynamics into assessments of ecosystem functionality in fragmented habitats.

Montane shrubby grasslands, as one of the world’s important ecosystems, are highly sensitive to climate change and human activities, especially in the subtropical regions experiencing rapid economic development. However, little is known about how anthropogenic activities, such as firebreak construction, interact with elevation to influence plant diversity in these ecosystems. Shrub and herbaceous communities were surveyed in subtropical montane shrubby grassland within Baishanzu National Park, eastern China. Nine transects were established along firebreaks, each with two edge plots near firebreak and two interior plots away firebreak, and twelve additional control plots in adjacent undisturbed areas. Species diversity was assessed using the Hill index. Our results revealed distinct responses of shrubs and herbs to firebreak disturbance and elevation. Firebreaks reduced shrub diversity but enhanced herb diversity, and both groups exhibited contrasting elevational patterns. In control areas, shrub diversity decreased while herb diversity increased with elevation, whereas in firebreak zones, these relationships were altered, with edge plots showing a hump-shaped diversity pattern. Differences in shrub diversity but not herbs between interior and edge plots decreased with elevation. Species composition also differed significantly between firebreak and control areas, driven mainly by elevation in control areas and by soil properties near firebreaks. These findings demonstrate that firebreak construction reshapes the elevation–diversity relationships of both herbs and shrubs, highlighting the sensitivity of high-elevation montane shrubby grasslands to small-scale disturbances. Effective firebreak management should therefore account for both elevational context and disturbance intensity to maintain ecosystem biodiversity and stability.

Habitat fragmentation is a major threat to biodiversity, and it usually leads to microclimate variations. Habitat quality (e.g. nutrients and moisture) and fungal symbioses play important roles in plant growth and ecosystem productivity. However, the impact of habitat fragmentation on plant aboveground biomass (AGB) is unclear. We examined the soil nutrients, rhizosphere fungal richness, and the AGB of 10 woody plant species on 10 islands of the same age but varying in size and isolation, in a land-bridge island system of subtropical China. Here we show that island size, soil nutrients, and fungal symbioses are key factors driving plant growth patterns in a fragmented island system. Plant AGB is positively correlated with soil phosphorus (P) but negatively correlated with richness of symbiotic fungi, suggesting that P content is more impactful than fungal symbiosis on plant growth in subtropical fragmented forests. Across all islands, low soil P and high symbiotic fungal richness lead to decreased plant AGB on small islands. These findings highlight the critical role of environmental filtering in shaping plant development within island fragments.

Species abundance distribution (SAD) combines species richness with species abundance in a community and is an important indicator of community structure. Although many studies have applied mathematical models to fit the SADs of plant communities, there are still few studies on the changes in the shape of SAD (i.e., the skewness of the SAD curves) along the environmental gradient. Especially for forest communities, it is still unclear whether the model fitting and shape change of SADs are consistent in different vegetation types. Here, 28 plots of 20 m × 20 m were set up in Hynobius amjiensis National Nature Reserve according to the main forest vegetation types. The species composition and abundance of each species were surveyed in each plot. The logseries model and the lognormal model were fitted to the SAD in each plot, and then the best-fit model was selected based on the corrected Akaike's Information Criteria (AICc). The α value in Gambin model and the η value in Weibull model were calculated to reflect the shape of SAD in each plot. The λ value in Weibull model was calculated to reflect the scale of SAD (i.e., the range observed in abundance). The relationship between altitude and the shape and scale of SAD was analyzed. The results were as follows: (1) The logseries model fitted SAD better than the lognormal model. (2) When all plots were included, there was no significant correlation between SAD shape (α and η) and altitude, but there was a significant positive correlation between the λ value and altitude. (3) There was a negative correlation between altitude and α and η values in the mixed evergreen and deciduous broad-leaved forests, and there was a significant positive correlation between the α value and altitude in the deciduous broad-leaved forests, while there was no significant correlations between both α value and η value and altitude. The results indicate that the model fitting and shape change of SADs along the environmental gradient are related to the vegetation types of the forest community. Therefore, it is necessary to consider the vegetation types when analyzing the relationship between SAD and impact factors in plant communities.

Large trees are essential for carbon storage and biodiversity conservation. While an increasing number of studies have focused on large trees in primary forests, little is known about them in secondary and planted forests. We surveyed 86,936 trees in secondary forests and 91,294 trees in planted forests in Zhejiang, China, to investigate the distribution patterns and determinants of large trees in these forests. We found a mean density of large trees (DBH ≥ 30 cm) of 15 ± 13 stems ha-1 in secondary forests and 11 ± 9 stems ha-1 in planted forests. Moreover, the mean density of trees with DBH ≥ 60 cm was 0.36 stems ha-1, indicating that large trees are particularly rare in secondary and planted forests. These large trees were primarily occurred in secondary forests that living in high-elevation area with less human exploitation and colder and wetter climates, and in planted forests with higher species richness and lower tree density. In addition, the density of large trees in these forests significantly increased with tree species richness and decreased with increasing tree density. These results indicate that the sparse large trees were the legacy of historical human activities in the studied area, but currently, the development of large trees is still limited by the improper forest structure characterized by low species diversity and high tree density. To better conserve large trees, there is an urgent need for enhanced conservation policies for secondary forests, such as establishing forest parks for forests with large trees, and implementing near-natural forest management practices for planted forests, which include planting mixed native tree species and maintaining moderate tree density.

Cupressus gigantea is an endangered species mainly distributed on beach land, down-slope, and middle-slope positions along the Yarlung Zangbo River on the Tibet Plateau of China, with an altitude ranging from 3000 to 3400 m. We investigated the rhizosphere and fine root microbiomes of C. gigantea at these three slope positions through metagenomic analysis. Slope positions had a greater influence on microbiome composition in the rhizosphere than that in the fine roots. Down- and middle-slope positions presented higher microbial richness indeces and community similarity, while a more complex co-occurrence network was observed in the beach land samples. Rhizosphere bacterial community assembly was determined via deterministic processes in the beach land and via stochastic processes in the down- and middle-slope positions. Archaeal and fungal community assemblies were both dominated by stochastic processes in the rhizosphere and fine roots at the three slope positions. Nitrogen (N) functional genes were more sensitive to changes in slope positions than phosphorus (N) functional genes. Soil properties explained more than 60% and 34% of the variations in the N and P functional genes and more than 30% and 10% of the variations in the microbiomes in the rhizosphere and fine roots, respectively. Variation in the microbiome was significantly driven by total nirtogen, total potassium, pH, and soil moisture in rhizosphere, and by pH and soil moisture in fine roots. Our observations suggest that the effect of slope position on the microbiomes of C. gigantea was greater for the rhizosphere than the fine roots, with down- and middle-slope positions presenting higher community similarity.

AimsThe relationship between habitat area and species evenness quantifies species relative abundance distribution changes across habitat fragments, providing more information than considering only the species richness to predict biodiversity distribution patterns in fragmented landscapes. However, unlike the species-area relationships (SARs), the Species Evenness-Area Relationship (SEARs) has yet to be explored across taxa at a large spatial scale. Here, we resolved how the relationship between species evenness and fragment area varies among taxonomic groups and environmental factors.LocationGlobal.TaxaInsecta, Aves, Amphibians and Squamata, Plantae, Arachnida, Mammalia, Mollusca.MethodsWe compiled 67 datasets from the FragSAD database, including information on fragments area, species richness, and species abundance of six taxa worldwide. We calculated the species evenness index for each fragment, which is independent of species richness, and tested the relationship between species evenness and fragment area across taxonomic groups. We also used the power model to fit SEAR for each dataset and identified landscape variables with a detectable impact on the occurrence of significant SEARs.ResultsIn contrast to the positive relationship between species richness and fragment area, species evenness was negatively affected by fragment area when controlling for other environmental factors and the relationships varied significantly among taxonomic groups. Specifically, there were significant negative associations between species evenness and fragment area for insects, birds, spiders, and mammals but not for plants and amphibians. Meanwhile, the occurrence of significant SEARs depends on the number of fragments and total fragment area.Main ConclusionsThe contrasting patterns of SEARs and SARs among taxonomic groups highlight the complexity of the mechanisms regulating biodiversity patterns. Although the number of species increases with the increase of fragment area, the decreased evenness implies community instability on larger fragments. Therefore, understanding the prevalence and underlying mechanisms in determining SEARs has critical implications for biodiversity conservation.

(1) Background: Heterotrophs can affect plant biomass and alter species diversity–productivity relationships. However, these studies were conducted in systems with a low nitrogen (N) availability, and it is unclear how heterotroph removal affects the relationship between plant species diversity and productivity in different N habitats. (2) Methods: Three typical understory herbaceous plants were selected to assemble the plant species diversity (three plant species richness levels (1, 2, and 3) and seven plant species compositions), and the control, insecticide, fungicide, and all removal treatments were performed at each plant species diversity level in systems with or without N addition treatments. (3) Results: In systems without N addition, the insecticide treatment increased the plant aboveground biomass, total biomass, and leaf area, while the fungicide treatment reduced the plant belowground biomass, root length, and root tip number; the presence of Bidens pilosa increased the plant aboveground biomass. Similarly, the presence of Bletilla striata increased the plant belowground biomass and root diameter under each heterotroph removal treatment. In systems with N addition, all removal treatments reduced the plant belowground biomass and increased the plant leaf area; the presence of B. pilosa significantly increased the plant aboveground biomass, total biomass, and root length under each heterotroph removal treatment. The presence of B. striata significantly increased the plant belowground biomass and leaf area under insecticide and fungicide treatments. (4) Conclusions: Heterotroph removal alters the plant species diversity–biomass relationship by affecting the plant functional traits in systems with different N availabilities. The impact of biodiversity at different trophic levels on ecosystem functioning should be considered under the background of global change.

Ongoing habitat loss and fragmentation caused by human activities represent one of the greatest causes of biodiversity loss. However, the effects of habitat loss and fragmentation are not felt equally among species. Here, we examined how habitat loss influenced the diversity and abundance of species from different trophic levels, with different traits, by taking advantage of an inadvertent experiment that created habitat islands from a once continuous forest via the creation of the Thousand Island Lake, a large reservoir in China. On 28 of these islands with more than a 9000-fold difference in their area (0.12-1154 ha), we sampled plants, herbivorous insects, and predatory insects using effort-controlled sampling and analyses. This allowed us to discern whether any observed differences in species diversity were due to passive sampling alone or to demographic effects that disproportionately influenced some species relative to others. We found that while most metrics of sampling effort-controlled diversity increased with island area, the strength of the effect was exacerbated for species in higher trophic levels. When we more explicitly examined differences in species composition among islands, we found that the pairwise difference in species composition among islands was dominated by species turnover but that nestedness increased with differences in island area, indicating that some species are more likely to be absent from smaller islands. Furthermore, by examining trends of several dispersal-related traits of species, we found that species with lower dispersal propensity tended to be those that were lost from smaller islands, which was observed for herbivorous and predatory insects. Our results emphasize the importance of incorporating within-patch demographic effects, as well as the taxa and traits of species when understanding the influence of habitat loss on biodiversity.

Dongtou National Marine Park(DNMP)locates at the southeast coast of China,and the climax vegetation belongs to the subtropical evergreen broadleaf forests.However,we are still unclear about the vegetation types on most islands in DNMP.The objective of this study is to investigate vegetation types and characteristics across islands in DNMP.We conducted vegetation survey by setting up 90 sampling plots on the islands in DNMP.Species composition and habitat information in each plot were recorded and vegetation type classification and naming were referred according to the Vegegraphy of China.A total of 3 Vegetation Formation Groups,8 Vegetation Formations,34 Alliances,and 80 Associations were found in DNMP.The widely distributed vegetation types included Pinus thunbergii evergreen needleleaf forest,Casuarina equisetifolia evergreen broadleaf forest,Acacia confuse evergreen broadleaf forest,Eurya emarginata evergreen broadleaf shrubland,and Eurya japonica evergreen broadleaf shrubland.Our finding provides basic and detail information of vegetation structure and composition in these continental islands in eastern China.

Abies beshanzuensis M. H. Wu is a critically endangered plant with only three wild mother trees in the world, it has a small distribution range limited to Baishanzu National Park, and its natural regeneration has been extremely low, with fewer than three seedlings appearing from 2007 to 2017. Despite the critically endangered status in China, little is known about the obstacles affecting the natural regeneration and reproduction of this species. In our study, we investigated various factors that could influence seed germination, seedling growth, seed quality, and overall production throughout the life cycle of A. beshanzuensis. Our findings highlighted the importance of litter removal in its natural habitat. Over five years following the removal of litter, we observed the emergence of 687 new seedlings, demonstrating a significant enhancement in both germination and seedling survival. Seedling abundance and mortality were greatly influenced by litter thickness, total carbon content, NO3--N, and available phosphorus. Seedlings height growth rate was significantly affected by litter coverage, canopy density at 1.3 m height, total nitrogen, and litter thickness. Additionally, the insufficient energy and lower values of actual photochemical rate, electron transfer rate, and photochemical quenching coefficient support in leaves with cones in the branch and branches with cones in the branch, contributed to abnormal development of female cones, leading to endosperm and embryo abortion. Our findings underscore the significant impact of environmental factors on seedling germination and growth, and highlight that insufficient energy support and reduced photosynthetic capability during female cone reproductive development may pose significant obstacles to the success of A. beshanzuensis.

Breed selection alters the coevolution of plant–microbiome associations that have developed over long periods of natural evolution. We investigated the effects of breed selection on the rhizosphere microbiomes and metabolites of hybrid parents (I101 and 84K) and their offspring (Q1–Q5) using metagenomics and untargeted metabolomics. Rhizosphere archaeal, bacterial and fungal community β-diversity significantly differed among hybrid parents and offspring, but only the dominant bacterial phyla and bacterial community α-diversity revealed significant differences. Approximately 5.49%, 14.90% and 7.86% of the archaeal, bacterial and fungal species significantly differed among the poplar hybrid parents and offspring. Rhizosphere microbial functional genes and metabolites were both clustered into the following three groups: I101 and 84K; Q2 and Q4; and Q1, Q3 and Q5. Compared with the hybrid parents, 15 phytochemical compounds were enriched in the hybrid offspring and explained 7.15%, 18.24% and 6.68% of the total variation in the archaeal, bacterial and fungal community compositions, respectively. Rhizosphere metabolites significantly affected the bacterial community, rather than the archaeal and fungal communities. Our observations suggested that poplar breed selection imposed greater selection pressure on the rhizosphere bacterial community, which was mainly driven by metabolites.

Managing invasive species requires identifying the factors that determine alien species invasion success. This study investigates how anthropogenic and biogeographical factors influence alien plant invasion in the Sanyang Wetlands, a human-dominated island system in Wenzhou City, China. Specifically, we analyzed whether human activities (e.g., habitat heterogeneity, proportion of road area, and cultivation) and island characteristics (e.g., island area, isolation) affect the diversity of native and invasive plant species similarly. We also assessed the applicability of the equilibrium theory of island biogeography to invasive plant species diversity and examined how these factors affect invasive plant species with different dispersal syndromes (anemochore, zoochore, and autochore). We found that both invasive and native species richness positively correlate with island area, habitat heterogeneity, and proportion of road area. However, although native species richness was negatively correlated with isolation, invasive species richness was not. The diversity and composition of invasive species with different dispersal syndromes were determined by different variables; for example, the composition and diversity of zoochores was increased by habitat heterogeneity, while anemochore species richness was increased by the proportion of road area, whereas anemochore species composition was influenced by distance to the nearest island. We conclude that habitat fragmentation differentially affects invasive and native plant diversity, aligning with the predictions of the equilibrium theory of island biogeography only for native species but not for invasive species. Our findings indicate that tailoring habitat attributes and regulating human activities could be effective strategies for mitigating the spread of invasive species in fragmented landscapes.

(1) Background: Plant diversity has long been assumed to predict soil microbial diversity. The mutualistic symbiosis between forest trees and ectomycorrhizal (EM) fungi favors strong correlations of EM fungal diversity with host density in terrestrial ecosystems. Nevertheless, in contrast with host tree effects, neighboring plant effects are less well studied. (2) Methods: In the study presented herein, we examined the α-diversity, community composition, and co-occurrence patterns of EM fungi in Quercus acutissima across different forest types (pure forests, mixed forests with Pinus tabuliformis, and mixed forests with other broadleaved species) to ascertain how the EM fungi of focal trees are related to their neighboring plants and to identify the underlying mechanisms that contribute to this relationship. (3) Results: The EM fungal community exhibited an overall modest but positive correlation with neighboring plant richness, with the associations being more pronounced in mixed forests. This neighboring effect was mediated by altered abiotic (i.e., SOC, TN, LC, and LP) and biotic (i.e., bacterial community) factors in rhizosphere soil. Further analysis revealed that Tomentella_badia, Tomentella_galzinii, and Sebacina_incrustans exhibited the most significant correlations with plant and EM fungal diversity. These keystone taxa featured low relative abundance and clear habitat preferences and shared similar physiological traits that promote nutrient uptake through contact, short-distance and medium-distance smooth contact-based exploration types, thereby enhancing the potential correlations between EM fungi and the neighboring plant community. (4) Conclusions: Our findings contribute to the comprehension of the effect of neighboring plants on the EM fungal community of focal trees of different forest communities and the biodiversity sensitivity to environmental change.

Ectomycorrhizal (ECM) fungi form the interface between soil and tree roots, playing critical roles in biogeochemical cycling in terrestrial ecosystems. Forest types influence ECM fungal colonization and host preferences; however, limited knowledge exists about neighborhood effects of tree species combinations on ECM fungal diversity patterns, and the consequences for microbial-mediated soil organic matter decomposition. Here, we compared Quercus acutissima ectomycorrhizas in pure (PF), broadleaf mixed (QBF), and Pinus mixed (QPF) forests and explored the possible links between ECM fungi and the physiological traits of free-living microbial decomposers. Results showed that the presence of pine neighbors increased Shannon diversity but decreased community similarity and stochasticity of focal ECM fungi. The increased ECM fungal diversity alleviates nutrient limitations for soil microorganisms and thus reduces investments for nutrient acquisition (especially for P), which is associated with increased microbial growth yields and potentially increased soil carbon stocks. Moreover, keystone ECM fungal assemblies primarily composed of Lactarius, Tomentella, and Cortinarius were identified as the most significant predictors of soil microbial physiological adaptions. Further analysis showed that biotic factors, especially bacterial richness, played a comparatively more important role in regulating ECM fungal diversity and function than edaphic factors. Together, our findings describe the complex relationships between plant-root-associated ECM fungal community structure and functionality within the framework of trait-based ecology, having important implications for ECM-mediated C cycling.