Brearley Francis Q, Press Malcolm C, Scholes Julie D
Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
New Phytol. 2003 Oct;160(1):101-110. doi: 10.1046/j.1469-8137.2003.00851.x. Epub 2003 Jul 28.
• In tropical rain forests the rate of litterfall is high, and is the most important nutrient cycling pathway in these ecosystems. We tested two hypotheses using seedlings of dipterocarp species: (1) addition of leaf litter improves growth; (2) and litter addition affects both ectomycorrhizal (ECM) colonization and community structure. • Three dipterocarp species with contrasting ecologies (Parashorea tomentella, Hopea nervosa and Dryobalanops lanceolata) were grown in a nursery in forest soil with or without the addition of litter. • Litter addition improved the growth of all three species. There was no effect of litter addition on total percentage ECM colonization but ECM diversity and percentage colonization by Cenococcum geophilum were lower with litter addition. Foliar δ N was lower in two of the three species grown in the presence of litter, reflecting the lower δ N of the litter compared with the soil. There was a negative correlation between δ N and percentage ECM, suggesting a role for ECMs in accessing litter-derived N sources. • This study shows that litter addition improved the growth of dipterocarp seedlings and that the ECM associations of dipterocarps facilitated access to this organic nutrient source. This has implications for the successful regeneration of seedlings in the rain forest understorey.
在热带雨林中，凋落物的掉落速率很高，且是这些生态系统中最重要的养分循环途径。我们使用龙脑香科树种的幼苗检验了两个假设：（1）添加落叶能促进生长；（2）添加落叶会影响外生菌根（ECM）的定殖和群落结构。三种生态习性不同的龙脑香科树种（绒毛娑罗双、狭叶坡垒和披针叶冰片香）在森林土壤的苗圃中种植，部分添加落叶。添加落叶促进了所有三种树种的生长。添加落叶对外生菌根定殖的总百分比没有影响，但外生菌根的多样性以及土生空团菌的定殖百分比在添加落叶的情况下较低。在添加落叶情况下生长的三种树种中的两种，其叶片的δN较低，这反映出与土壤相比，落叶的δN较低。δN与外生菌根百分比之间呈负相关，表明外生菌根在获取落叶衍生氮源方面发挥了作用。这项研究表明，添加落叶促进了龙脑香科树种幼苗的生长，且龙脑香科树种的外生菌根共生关系有助于获取这种有机养分来源。这对雨林林下幼苗的成功更新具有重要意义。
