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The mechanisms underlying interspecific variation in conspecific negative density dependence (CNDD) are poorly understood. Using a multilevel modeling approach, we combined long-term seedling demographic data from a subtropical forest plot with soil fungal community data by means of DNA sequencing to address the feedback of various guilds of soil fungi on the density dependence of trees. We show that mycorrhizal type mediates tree neighborhood interactions at the community level, and much of the interspecific variation in CNDD is explained by how tree species differ in their fungal density accumulation rates as they grow. Species with higher accumulation rates of pathogenic fungi suffered more from CNDD, whereas species with lower CNDD had higher accumulation rates of ectomycorrhizal fungi, suggesting that mutualistic and pathogenic fungi play important but opposing roles.

Flagship species have been used widely as umbrella species (i.e., species with large home range whose protection often provides protection for sympatric species) in the management of China’s nature reserves. This conflation of flagship and umbrella species is best represented by the giant panda (Ailuropoda melanoleuca) and other large, endangered mammals designated as conservation targets in site selection and planning of reserves. Few empirical studies have tested the effectiveness of flagship species as surrogates for a broader range of sympatric species. Using extensive camera-trap data, we examined the effectiveness of management zones designated to protect flagship (target) species in conserving sympatric species in 4 wildlife reserves (Gutianshan, Changqing, Laohegou, and Wolong). We tested whether the progression from peripheral to core zones was associated with an increasing habitat association for both target and sympatric species. The distribution patterns of the study species across the zones in each reserve indicated a disparity between management zones and the species’ habitat requirements. Management zone was included in the final model for all target species, and most of them had higher occurrence in core zones relative to less-protected zones, but zone was not a predictor for most of the sympatric species. When management zone was associated with the occurrence of sympatric species, threatened species generally had higher detections in core zones, whereas common species had higher detections outside of the core zone. Our results suggested that reserve planning based on flagship species does not adequately protect sympatric species due to their specialized habitat requirements. We recommend re-examining the effectiveness of management zoning and urge a multispecies and reserve-wide monitoring plan to improve protection of China’s wildlife. Las especies bandera se han utilizado ampliamente como especies paraguas (es decir, especies con una extensa distribución cuya protección frecuentemente proporciona protección para especies simpátricas) en el manejo de las reservas naturales de China. Esta combinación de especie bandera y especie paraguas tiene su mejor representación en el panda gigante (Ailuropoda melanoleuca) y otros grandes mamíferos en peligro de extinción designados como objetivos de conservación en la selección de sitio y la planeación de reservas. Pocos estudios empíricos han probado la efectividad de las especies bandera como sustitutas de una especie simpátrica con una distribución más amplia. Con datos numerosos de cámaras trampa, examinamos la efectividad de las zonas de manejo designadas para proteger a las especies bandera (objetivo) en la conservación de especies simpátricas dentro de cuatro reservas de fauna (Gutianshan, Changqing, Laohegou y Wolong). Probamos si la progresión de las zonas periféricas hacia las zonas núcleo estaba relacionada con asociaciones crecientes de hábitat tanto para las especies objetivo como para las simpátricas. Los patrones de distribución del estudio de especies a lo largo de las zonas en cada reserva indicaron una disparidad entre las zonas de manejo y los requerimientos de hábitat de las especies. La zona de manejo se incluyó dentro del modelo final para todas las especies objetivo y la mayoría de ellas tuvo una presencia más alta en las zonas núcleo en relación con las zonas de menor protección. Cuando la zona de manejo se asoció a la presencia de especies simpátricas, las especies amenazadas generalmente tuvieron un mayor número de detecciones en la zona núcleo, mientras que las especies comunes tuvieron un número más elevado de detecciones fuera de la zona núcleo. Nuestros resultados sugieren que la planeación de reservas basada en las especies bandera no protege adecuadamente a las especies simpátricas debido a sus requerimientos especializados de hábitat. Recomendamos una reexaminación de la efectividad del manejo de zonación y urgimos que se genere un plan de monitoreo multiespecífico en toda la reserva para mejorar la protección de la fauna en China. 旗舰物种被广泛地作为伞护物种 (指活动范围广、对其投人的保护措施能够同时有益于其它同域分布物 种的物种) 用于中国自然保护区的管理。旗舰种和伞护种概念的混淆最为突出地体现在, 选择以大熊猫为代表 的大型濒危兽类作为主要保护对象来确定保护区的选址和规划。很少有实证性的研究来检验伞护种是否能有效 代表同域分布物种的保护需求。我们基于大数据量的红外相机调查, 评估了中国 4 个野生动物保护区 (古田山、 长青、老河沟和卧龙) 针对旗舰物种 ( 即主要保护对象) 划定的管理分区对同域分布物种保护的有效性。我们分 析了从保护区实验区向缓冲区、核心区过渡的过程中, 主要保护对象和其它同域分布物种是否均表现出更强的 选择性。多个物种在保护区各个分区内的分布格局显示, 管理分区和物种的栖息地需求并不一致。分区是影响 主要保护对象分布的因素之一。相比实验区和缓冲区, 多数保护对象更多地出现在核心区。然而, 分区对绝大多 数同域分布物种而言, 并不是一个影响其分布的显著因素。对于部分分布受分区影响的同域分布物种而言, 受 威胁物种通常偏好核心区内的生境, 而常见种则偏好实验区内的生境。我们的研究结果表明, 旗舰物种通常有 特化的栖息地需求, 将它们作为同域分布物种的代表以指导保护区规划, 并不能有效保护其它同域分布物种。 我们建议保护区应重新评估管理分区的有效性, 并采用基于多物种的、覆盖保护区全境的监测方案, 以促进对 中国野生动物的有效保护。

Forging strong links between traits and performance is essential for understanding and predicting community assembly and dynamics. Functional trait analyses of trees that have correlated single-trait values with measures of performance such as growth and mortality have generally found weak relationships. A reason for these weak relationships is the failure to use individual-level trait data while simultaneously putting that data into the context of the abiotic setting, neighborhood composition, and the remaining axes constituting the overall phenotype. Here, utilizing detailed growth and trait data for 59 species of trees in a subtropical forest, we demonstrate that the individual-level functional trait values are strongly related to individual growth rates, and that the strength of these relationships critically depends on the context of that individual. We argue that our understanding of trait-performance relationships can be greatly improved with individuallevel data so long as that data is put into the proper context.

The classical environmental control model assumes that species distribution is determined by the spatial variation of underlying habitat conditions. This niche-based model has recently been challenged by the neutral theory of biodiversity which assumes that ecological drift is a key process regulating species coexistence. Understanding the mechanisms that maintain biodiversity in communities critically depends on our ability to decompose the variation of diversity into the contributions of different processes affecting it. Here we investigated the effects of pure habitat, pure spatial, and spatially structured habitat processes on the distributions of species richness and species composition in a recently established 24-ha stem-mapping plot in the subtropical evergreen broad-leaved forest of Gutianshan National Nature Reserve in East China. We used the new spatial analysis method of principal coordinates of neighbor matrices (PCNM) to disentangle the contributions of these processes. The results showed that (1) habitat and space jointly explained ~53% of the variation in richness and ~65% of the variation in species composition, depending on the scale (sampling unit size); (2) tree diversity (richness and composition) in the Gutianshan forest was dominantly controlled by spatially structured habitat (24%) and habitat-independent spatial component (29%); the spatially independent habitat contributed a negligible effect (6%); (3) distributions of richness and species composition were strongly affected by altitude and terrain convexity, while the effects of slope and aspect were weak; (4) the spatial distribution of diversity in the forest was dominated by broad-scaled spatial variation; (5) environmental control on the one hand and unexplained spatial variation on the other (unmeasured environmental variables and neutral processes) corresponded to spatial structures with different scales in the Gutianshan forest plot; and (6) five habitat types were recognized; a few species were statistically significant indicators of three of these habitats, whereas two habitats had no significant indicator species. The results suggest that the diversity of the forest is equally governed by environmental control (30%) and neutral processes (29%). In the fine-scale analysis (10 × 10 m cells), neutral processes dominated (43%) over environmental control (20%).

This article also appears in: Virtual Issue: Filling gaps in our understanding of belowground plant traits across the world

ABSTRACT Fungi have a huge biodiversity and play important roles in soil biogeochemical cycling in island ecosystems. Although island biogeography has been widely studied for macroorganisms, fungal community assembly in true islands and its relationship with island area are less documented. We examined soil fungal communities in 18 oceanic islands of two types (eight non-coral islands and 10 coral islands) using the Illumina MiSeq sequencing technique. Our results showed that fungal α-diversity (species richness) was substantially different among the oceanic islands, with a higher value in non-coral islands than in coral islands. Fungal α-diversity was significantly affected by soil potassium and magnesium (Mg) and plant communities in non-coral islands, whereas only soil Mg significantly affected it in coral islands. Soil fungal community composition was significantly different in the non-coral and coral islands and was influenced by soil property, plant community and spatial distance. The ecological stochasticity model showed that the fungal community assembly was mainly governed by deterministic processes regardless of island type. Fungal β-diversity, but not α-diversity, increased significantly with increasing island area. These findings have implications for the better prediction of soil fungal community dynamics in island systems and biodiversity conservation in fragmented habitats. Soil fungal β-diversity rather than α-diversity increases with increasing oceanic island area.

Background and aims Home-field advantage (HFA) hypothesis predicts that plant litter decomposes faster beneath the plant species from which it was derived than beneath other plant species. However, it remains unclear, which groups of soil organisms drive HFA effects across a wide range of litter quality and forest types. Methods We set up a reciprocal transplant decomposition experiment to quantify the HFA effects of broadleaf, coniferous and bamboo litters. Litterbags of different mesh sizes and high-throughput pyrosequencing of microbial rRNA gene were used to test the contribution of different decomposer groups to HFA effect. Results The recalcitrant broadleaf litter and the labile bamboo litter exhibited HFA. Presence of meso-and macrofauna did not substantially change the HFA effects. Bacterial and fungal community composition on litters were significantly influenced by litter type. Bacterial community composition remained unchanged when the same litter was decomposed in different forest types, whereas fungal community composition on broadleaf and bamboo litters were significantly influenced by incubation site. Conclusions Our data demonstrate specific association between fungal community composition and faster litter decomposition in the home site, suggesting that fungi probably participate in driving the HFA effect of broadleaf and bamboo litters.

The relative importance of deterministic and neutral processes on community assembly is currently a topic of much debate among ecologists. Analyzing species-environment associations is an effective way to assess the importance of deterministic process such as niche differentiation, but both habitat association and dispersal limitation can produce similar patterns of spatial aggregation in species. Therefore, it is crucial to control for the impact of dispersal limitation on species distributions when analyzing species-environment associations. We sampled soil with high resolutions in a 24 ha stem-mapped subtropical forest and tested plantsoil associations. We controlled for the influence of dispersal limitation by employing the homogeneous Thomas process to simulate the effect of dispersal limitation on the aggregation of tree species. After controlling for the effect of dispersal limitation, we found that the spatial heterogeneity of soil properties was associated with distributions of 88.2% (90 of 102 species) of tree species in this subtropical forest. Furthermore, not only did soil properties influence the distribution of tree species, but also tree species tended to affect properties of the soil around them. The soil factors most strongly influencing species distributions were TC, TN, TP, K, Mg, Si, soil moisture, and bulk density. We found the spatial heterogeneity of soil properties to be strongly associated with tree species distributions. Niche partitioning of soil gradients contributed substantially to species coexistence in this subtropical forest.

Question: Do tree and shrub species in an evergreen broadleaf forest show similar habitat associations across different life stages? Location: A 24-ha evergreen broadleaf forest plot in a heterogeneous landscape in Gutianshan National Nature Reserve, Zhejiang Province, Eastern China. Methods: Species having positive associations with four habitat types (low valley, low ridge, upper valley, and upper ridge) at three life stages (sapling, juvenile, and mature stages) were compared for 60 tree and shrub species using torus-translation tests. Results: A total of 117 significant positive associations with the four habitats were observed at the three life stages (43, 41, and 33 at the sapling, juvenile, and mature stages, respectively). For the 52 species significantly associated with habitats, only 16 were associated with the same habitat across all three stages. The majority of associated species at the juvenile stage (34 out of 40) were associated with the same habitat at their sapling stage, whereas half of species at the mature stage had consistent associations with the same habitat at their sapling stage. More species were associated with the upper ridge at the sapling and juvenile stages compared to the mature stage. Conversely, more species were associated with the low valley at the mature stage compared to the sapling and juvenile stages. Conclusions: Our results indicate that species ecological habitat associations can differ between developmental stages beyond 1 cm DBH, as most species habitat preferences were consistent from the sapling stage to the juvenile stage but changed at the mature stage.

Interactions among neighbors influence the structure of communities of sessile organisms. Closely related species tend to share habitat and resource requirements and to interact with the same mutualists and natural enemies so that the strength of interspecific interactions tends to decrease with evolutionary divergence time. Nevertheless, the degree to which such phylogenetically related ecological interactions structure plant communities remains unclear. Using data from five large mapped forest plots combined with a DNA barcode mega-phylogeny, we employed an individual-based approach to assess the collective effects of focal tree size on neighborhood phylogenetic relatedness. Abundance-weighted average divergence time for all neighbors (ADT_all) and for heterospecific neighbors only (ADT_hetero) were calculated for each individual of canopy tree species. Within local neighborhoods, we found phylogenetic composition changed with focal tree size. Specifically, significant increases in ADT_all with focal tree size were evident at all sites. In contrast, there was no significant change in ADT_hetero with tree size in four of the five sites for both sapling-sized and all neighbors, even at the smallest neighbourhood scale (0–5 m), suggesting a limited role for phylogeny-dependent interactions. However, there were inverse relationships between focal tree size and the proportion of heterospecific neighbors belonging to closely related species at some sites, providing evidence for negative phylogenetic density dependence. Overall, our results indicate that negative interaction with conspecifics had a much greater impact on neighborhood assemblages than interactions among closely related species and could contribute to community structure and diversity maintenance in different forest communities.