Bachelot Benedicte, Uriarte María, Zimmerman Jess K, Thompson Jill, Leff Jonathan W, Asiaii Ava, Koshner Jenny, McGuire Krista
Department of Ecology, Evolution and Environmental Biology, Columbia University, 1200 Amsterdam Avenue, New York, New York, 10027, USA.
Department of Environmental Sciences, University of Puerto Rico, Río Piedras Campus, San Juan, Puerto Rico, 00936, USA.
Ecol Appl. 2016 Sep;26(6):1881-1895. doi: 10.1890/15-1397.1.
Our understanding of the long-lasting effects of human land use on soil fungal communities in tropical forests is limited. Yet, over 70% of all remaining tropical forests are growing in former agricultural or logged areas. We investigated the relationship among land use history, biotic and abiotic factors, and soil fungal community composition and diversity in a second-growth tropical forest in Puerto Rico. We coupled high-throughput DNA sequencing with tree community and environmental data to determine whether land use history had an effect on soil fungal community descriptors. We also investigated the biotic and abiotic factors that underlie such differences and asked whether the relative importance of biotic (tree diversity, basal tree area, and litterfall biomass) and abiotic (soil type, pH, iron, and total carbon, water flow, and canopy openness) factors in structuring soil fungal communities differed according to land use history. We demonstrated long-lasting effects of land use history on soil fungal communities. At our research site, most of the explained variation in soil fungal composition (R = 18.6%), richness (R = 11.4%), and evenness (R = 10%) was associated with edaphic factors. Areas previously subject to both logging and farming had a soil fungal community with lower beta diversity and greater evenness of fungal operational taxonomic units (OTUs) than areas subject to light logging. Yet, fungal richness was similar between the two areas of historical land use. Together, these results suggest that fungal communities in disturbed areas are more homogeneous and diverse than in areas subject to light logging. Edaphic factors were the most strongly correlated with soil fungal composition, especially in areas subject to light logging, where soils are more heterogenous. High functional tree diversity in areas subject to both logging and farming led to stronger correlations between biotic factors and fungal composition than in areas subject to light logging. In contrast, fungal richness and evenness were more strongly correlated with biotic factors in areas of light logging, suggesting that these metrics might reflect long-term associations in old-growth forests. The large amount of unexplained variance in fungal composition suggests that these communities are structured by both stochastic and niche assemblage processes.
我们对人类土地利用对热带森林土壤真菌群落的长期影响的了解有限。然而，所有现存热带森林中超过70%生长在前农业区或采伐区。我们调查了波多黎各一片次生热带森林中土地利用历史、生物和非生物因素以及土壤真菌群落组成和多样性之间的关系。我们将高通量DNA测序与树木群落和环境数据相结合，以确定土地利用历史是否对土壤真菌群落特征有影响。我们还研究了造成这些差异的生物和非生物因素，并询问生物（树木多样性、基部树面积和凋落物生物量）和非生物（土壤类型、pH值、铁、总碳、水流和林冠开阔度）因素在构建土壤真菌群落中的相对重要性是否因土地利用历史而异。我们证明了土地利用历史对土壤真菌群落有长期影响。在我们的研究地点，土壤真菌组成（R = 18.6%）、丰富度（R = 11.4%）和均匀度（R = 10%）中大部分可解释的变异与土壤因素有关。与轻度采伐区相比，先前经历过采伐和耕种的地区土壤真菌群落的β多样性较低，真菌操作分类单元（OTU）的均匀度更高。然而，这两个历史土地利用区域的真菌丰富度相似。总之，这些结果表明，受干扰地区的真菌群落比轻度采伐地区更均匀、更多样化。土壤因素与土壤真菌组成的相关性最强，特别是在轻度采伐地区，那里的土壤更加异质。与轻度采伐地区相比，经历过采伐和耕种地区的高功能树木多样性导致生物因素与真菌组成之间的相关性更强。相比之下，轻度采伐地区的真菌丰富度和均匀度与生物因素的相关性更强，这表明这些指标可能反映了原始森林中的长期关联。真菌组成中大量无法解释的变异表明，这些群落是由随机和生态位组装过程构建的。
