Data from: The spatial scaling of saprotrophic fungal beta diversity in decomposing leaves

Assembly of fungal communities remains poorly understood in part because of the daunting range of spatial scales that may be involved in this process. Here, we use individual leaves as a natural sampling unit, comprising spatially distinct habitat and/or resource patches with unique histories and suites of resources. Spatial patterns in fungal beta diversity were tested for consistency with the metacommunity paradigms of species sorting and neutral dynamics. Thirty senesced leaves were collected from the forest floor (O horizon) in replicate upland forest, riparian forest and vernal pool habitats. We quantified spatial distance between leaves, and fungal community composition was assayed by terminal restriction fragment length polymorphism. Significant distance-decay relationships were detected at all but one upland site. This is the first study where changes in fungal community composition were quantified across discrete adjacent habitat patches, providing evidence that fungal distance decay is operational at a scale of centimetres. Although leaves of differing lignin contents were sampled from each site, leaf type was not consistently important in explaining variation in fungal community composition. However, depth of a leaf within the forest floor significantly influenced community composition at five of six sites. Environmental heterogeneity associated with depth could include moisture gradients, relative influence of soil or spore colonization, and impact of forest floor biotic community (i.e. collembola and earthworms). Because the influence of spatial distance and depth on fungal community composition could not be disentangled, both species-sorting and neutral processes may be embedded within the distance-decay relationships that we found.

真菌群落的组装过程迄今仍未得到充分阐释，其部分原因在于该过程所涉及的空间尺度范围极为宽泛，令人难以把握。本研究以单片叶片作为自然采样单元，这些叶片对应着空间上相互独立的生境或资源斑块，各自拥有独特的定植历史与资源组合。本研究针对真菌beta多样性的空间分布模式，检验其是否符合物种分选（species sorting）与中性动态（neutral dynamics）两类集合群落（metacommunity）范式。研究人员从旱地森林、河岸森林与季节性水池（vernal pool）三类生境的重复样地中，分别采集了30片处于枯落阶段的叶片，采样区域均为森林地表（O层）。研究人员量化了叶片间的空间距离，并通过末端限制性片段长度多态性（terminal restriction fragment length polymorphism，T-RFLP）技术测定了真菌群落组成。除一处旱地森林样地外，其余所有样地均检测到显著的距离衰减关系（distance-decay relationship）。本研究首次针对离散相邻生境斑块间的真菌群落组成变化进行量化分析，证实真菌群落的距离衰减效应在厘米尺度上即可发挥作用。尽管各采样点均采集了木质素含量存在差异的叶片，但叶片类型并不能稳定解释真菌群落组成的变异。然而，在6个样地中的5个样地中，叶片在森林凋落物层中的埋藏深度对真菌群落组成存在显著影响。与埋藏深度相关的环境异质性可能包括湿度梯度、土壤或孢子定植的相对影响，以及森林凋落物层生物群落（即弹尾虫（collembola）与蚯蚓）的作用。由于无法区分空间距离与埋藏深度对真菌群落组成的各自影响，本研究发现的距离衰减关系中，可能同时包含了物种分选与中性动态两类过程。