Tree communities and soil properties influence fungal community assembly in neotropical forests

The influence exerted by tree communities, topography and soil chemistry
on the assembly of macrofungal communities remains poorly understood,
especially in highly diverse tropical forests. Here, we used a large
dataset that combines inventories of macrofungal Basidiomycetes fruiting
bodies, tree species composition and measurements for 16 soil
physico-chemical parameters, collected in 34 plots located in four sites
of lowland rainforests in French Guiana. Plots were established on three
different topographical conditions: hilltop, slope and seasonally flooded
soils. We found hyperdiverse Basidiomycetes communities, mainly comprising
members of Agaricales and Polyporales. Phosphorus, clay contents and base
saturation in soils strongly varied across plots and shaped the richness
and composition of tree communities. The latter composition explained 23%
of the variation in the composition of macrofungal communities, probably
through high heterogeneity of the litter chemistry and selective effects
of biotic interactions. The high local heterogeneity of habitats
influenced the distribution of both macrofungi and trees, as a result of
diversed local soil hydromorphic conditions associated to contrasting soil
chemistry. This first regional study across habitats of French Guiana
forests revealed new niches for macrofungi, such as ectomycorrhizal ones,
and illustrate how macrofungi inventories are still paramount to can be to
understand the processes at work in the tropics.

树木群落、地形与土壤化学对大型真菌群落组装的影响仍不甚明晰，在物种高度多样的热带森林中尤为如此。本研究依托一套采集自法属圭亚那4处低地热带雨林34个样方的大型数据集，该数据集整合了大型担子菌（Basidiomycetes）子实体调查数据、树木物种组成数据以及16项土壤理化参数测定结果。所有样方均设置于3种不同地形条件下：山顶、坡地与季节性淹水土壤。本研究发现了物种超多样的担子菌群落，类群主要涵盖伞菌目（Agaricales）与多孔菌目（Polyporales）成员。土壤中的磷含量、黏粒占比与盐基饱和度在各样方间差异显著，并塑造了树木群落的物种丰富度与组成。树木群落组成可解释23%的大型真菌群落组成变异，这一关联可能通过凋落物化学的高度异质性以及生物交互的筛选效应实现。生境的高度局域异质性影响了大型真菌与树木的分布格局，这源于与迥异土壤化学相关的多样局域土壤水成条件。这项针对法属圭亚那森林生境的首个区域性研究，揭示了外生菌根真菌等大型真菌的新生态位，并证实大型真菌调查仍是解析热带生态运作机制的核心手段。