Department of Biology, Stanford University, Stanford, California, 94305-5020, USA.
School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, 68588-0118, USA.
Ecology. 2020 Aug;101(8):e03083. doi: 10.1002/ecy.3083. Epub 2020 Jun 1.
While work in temperate forests suggests that there are consistent differences in plant-soil feedback (PSF) between plants with arbuscular and ectomycorrhizal associations, it is unclear whether these differences exist in tropical rainforests. We tested the effects of mycorrhizal type, phylogenetic relationships to overstory species, and soil fertility on the growth of tree seedlings in a tropical Bornean rainforest with a high diversity of both ectomycorrhizal and arbuscular mycorrhizal trees. We found that ectomycorrhizal tree seedlings had higher growth in soils conditioned by close relatives and that this was associated with higher mycorrhizal colonization. By contrast, arbuscular mycorrhizal tree seedlings generally grew more poorly in soils conditioned by close relatives. For ectomycorrhizal species, the phylogenetic trend was insensitive to soil fertility. For arbuscular mycorrhizal seedlings, however, the effect of growing in soils conditioned by close relatives became increasingly negative as soil fertility increased. Our results demonstrate consistent effects of mycorrhizal type on plant-soil feedbacks across forest biomes. The positive effects of ectomycorrhizal symbiosis may help explain biogeographic variation across tropical forests, such as familial dominance of the Dipterocarpaceae in southeast Asia. However, positive feedbacks also raise questions about the role of PSFs in maintaining tropical diversity.
虽然在温带森林中的研究表明，丛枝菌根和外生菌根植物之间存在着一致的植物-土壤反馈（PSF）差异，但在热带雨林中这些差异是否存在还不清楚。我们测试了菌根类型、与上层物种的系统发育关系以及土壤肥力对婆罗洲热带雨林中高多样性的外生菌根和丛枝菌根树木的幼苗生长的影响。我们发现，外生菌根树种在亲缘关系较近的土壤中生长得更好，这与较高的菌根定殖有关。相比之下，丛枝菌根树种通常在亲缘关系较近的土壤中生长得更差。对于外生菌根树种来说，系统发育趋势对土壤肥力不敏感。然而，对于丛枝菌根树种来说，在亲缘关系较近的土壤中生长的影响随着土壤肥力的增加而变得越来越负面。我们的结果表明，菌根类型对跨森林生物群落的植物-土壤反馈具有一致的影响。外生菌根共生的积极影响可能有助于解释热带森林中的生物地理变异，例如东南亚的龙脑香科的家族优势。然而，正反馈也提出了关于 PSF 在维持热带多样性中的作用的问题。
