Data from: Tropical forest type influences community assembly processes in arbuscular mycorrhizal fungi

Aim: Plant community assembly in tropical rainforest has been shown to be
largely governed by stochastic processes, but as arbuscular mycorrhizal
(AM) fungi display limited host preference, they may not follow the same
stochastic assembly pattern. Here, we determined the relative importance
of environmental and spatial drivers responsible for the community
assembly process of AM fungi in two types of tropical rainforest
(semideciduous rainforest and dense ombrophilous forests). Location:
Atlantic rainforest in northeastern Brazil, South America. Taxon:
Arbuscular mycorrhizal fungi (Glomeromycota). Methods: We collected root
samples from eight protected areas of Atlantic forest along a 700 km
transect in northeastern Brazil. We measured the relative importance of
deterministic and stochastic processes by redundancy analysis (RDA) and
variation partitioning in comparison with null expectations using ad hoc
generated neutral communities. Furthermore, we accessed species
associations from co-occurrence data, at different scales using a Bayesian
approach of Hierarchical Modelling of Species Communities (HMSC). Results:
Overall, the extent to which stochastic and deterministic processes
affected community assembly depended on the forest type and the spatial
scale. Specifically, we found that abiotic and biotic predictors of AM
fungal community assemblages are related to environmental homogeneity in
tropical rainforests. Main conclusions: The results of the study show that
dynamics in community assembly was clearly different between the two
forest types, and that the difference most likely is due to differences in
responses to environmental variables.

研究目的：热带雨林植物群落构建过程长期被认为主要由随机过程主导，但由于丛枝菌根（arbuscular mycorrhizal, AM）真菌的宿主偏好性有限，其群落构建可能并不遵循相同的随机组装模式。本研究旨在明确环境与空间驱动因子在两类热带雨林——半落叶雨林与致密云雾雨林——的丛枝菌根真菌群落构建过程中的相对重要性。研究地点：南美洲巴西东北部的大西洋沿岸热带雨林。研究类群：丛枝菌根真菌（球囊菌门，Glomeromycota）。研究方法：沿巴西东北部700公里的样带，在8处大西洋森林保护地采集根系样本。通过冗余分析（redundancy analysis, RDA）与变异划分，并结合临时生成的中性群落的零假设期望进行对比，以此量化确定性过程与随机过程的相对重要性。此外，本研究采用物种群落层级模型（Hierarchical Modelling of Species Communities, HMSC）的贝叶斯方法，在不同空间尺度上基于共现数据分析物种关联。研究结果：整体而言，随机与确定性过程对群落构建的影响程度取决于森林类型与空间尺度。具体而言，本研究发现丛枝菌根真菌群落组装的非生物与生物预测因子与热带雨林的环境异质性密切相关。研究结论：本研究结果表明，两类森林的群落构建动态存在显著差异，这种差异极有可能源于二者对环境变量的响应模式不同。