Arbuscular mycorrhizal fungal communities in soils under three phytophysiognomies of the Brazilian Atlantic Forest

ABSTRACT Arbuscular mycorrhizal fungi (AMF) play an important role in plant community productivity and structure, and so studying the factors that affect the diversity and structure of this fungal community is important for understanding their ecology in tropical forests. We investigated AMF spore communities and root colonization under three forest phytophysiognomies (Restinga Forest, REF; Lowland Ombrophilous Dense Forest, LLF; and Montane Ombrophilous Dense Forest, MTF). Spore abundance was lowest in LLF and highest in REF, with no statistical differences relative to MTF. Spore diversity indices and root colonization rates were not statistically different among the phytophysiognomies. However, principal components analysis revealed that AMF community structure differed according to forest phytophysiognomy. Hierarchical partitioning analysis indicated that most of the AMF community variables were better explained by phytophysiognomy than by chemical and physical attributes of the soil. In addition to the plant community, clay content, pH, Boron, P, S and CEC best explained some of the AMF community variables. Thus, we conclude that while several factors determine AMF community structure in the Atlantic Forest, phytophysiognomy is the most significant.

摘要：丛枝菌根真菌（Arbuscular mycorrhizal fungi, AMF）在植物群落生产力与结构构建中发挥着重要作用，因此探究影响该真菌群落多样性与结构的驱动因子，对于理解热带森林中该类真菌的生态学特征具有重要意义。本研究针对三种森林植被型——雷斯廷加森林（Restinga Forest, REF）、低地密湿润林（Lowland Ombrophilous Dense Forest, LLF）以及山地密湿润林（Montane Ombrophilous Dense Forest, MTF）下的AMF孢子群落与根系定殖情况展开了调查。结果显示，孢子丰度在LLF样地中最低、REF样地中最高，与MTF样地相比无统计学差异；不同植被型下的孢子多样性指数与根系定殖率均未表现出统计学差异。然而主成分分析结果表明，AMF群落结构随森林植被型的不同而存在显著差异。分层分割分析结果表明，相较于土壤理化属性，植被型能够更好地解释多数AMF群落相关变量的变异。除植物群落外，黏粒含量、pH值、硼元素、磷元素、硫元素以及阳离子交换量（CEC）可较好地解释部分AMF群落相关变量的变异。综上，尽管大西洋森林内的AMF群落结构受多种因子共同调控，但植被型仍是其中最为关键的驱动因子。