Waldrop Mark P, Zak Donald R, Blackwood Christopher B, Curtis Casey D, Tilman David
School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI 48109-1115, USA.
Ecol Lett. 2006 Oct;9(10):1127-35. doi: 10.1111/j.1461-0248.2006.00965.x.
Despite decades of research, the ecological determinants of microbial diversity remain poorly understood. Here, we test two alternative hypotheses concerning the factors regulating fungal diversity in soil. The first states that higher levels of plant detritus production increase the supply of limiting resources (i.e. organic substrates) thereby increasing fungal diversity. Alternatively, greater plant diversity increases the range of organic substrates entering soil, thereby increasing the number of niches to be filled by a greater array of heterotrophic fungi. These two hypotheses were simultaneously examined in experimental plant communities consisting of one to 16 species that have been maintained for a decade. We used ribosomal intergenic spacer analysis (RISA), in combination with cloning and sequencing, to quantify fungal community composition and diversity within the experimental plant communities. We used soil microbial biomass as a temporally integrated measure of resource supply. Plant diversity was unrelated to fungal diversity, but fungal diversity was a unimodal function of resource supply. Canonical correspondence analysis (CCA) indicated that plant diversity showed a relationship to fungal community composition, although the occurrence of RISA bands and operational taxonomic units (OTUs) did not differ among the treatments. The relationship between fungal diversity and resource availability parallels similar relationships reported for grasslands, tropical forests, coral reefs, and other biotic communities, strongly suggesting that the same underlying mechanisms determine the diversity of organisms at multiple scales.
尽管经过了数十年的研究，但人们对微生物多样性的生态决定因素仍知之甚少。在此，我们检验了关于调节土壤中真菌多样性的因素的两种替代性假说。第一种假说认为，较高水平的植物残体产量会增加限制性资源（即有机底物）的供应，从而增加真菌多样性。另一种观点则认为，更高的植物多样性会增加进入土壤的有机底物的范围，从而增加更多种类的异养真菌可占据的生态位数量。在由1至16个物种组成并已维持了十年的实验性植物群落中，我们同时检验了这两种假说。我们使用核糖体基因间隔区分析（RISA），结合克隆和测序，来量化实验性植物群落中的真菌群落组成和多样性。我们将土壤微生物生物量用作资源供应的时间综合指标。植物多样性与真菌多样性无关，但真菌多样性是资源供应的单峰函数。典范对应分析（CCA）表明，植物多样性与真菌群落组成存在关联，尽管不同处理之间RISA条带和操作分类单元（OTU）的出现情况并无差异。真菌多样性与资源可用性之间的关系与在草原、热带森林、珊瑚礁和其他生物群落中报道的类似关系相似，这有力地表明相同的潜在机制在多个尺度上决定了生物的多样性。
