Shifts in the arbuscular mycorrhizal fungal community composition of Betula alnoides along young, middle-aged plantation and adjacent natural forest

Betula alnoides is a fast-growing and native timber species prevalently planted in tropical and subtropical areas of southern China. Despite the large-scale development of B. alnoides plantations, knowledge of its association with arbuscular mycorrhizal fungi (AMF) is limited. In the present study, we chose young (3-year-old sapling, P3y) and middle-aged (12-year-old stand, P12y) B. alnoides plantations and adjacent native forest (N) in the Puwen Tropical Forest Experimental Station located in Xishuangbanna prefecture of Yunnan Province, southwestern China, as study materials and explored the change in AMF community composition in the plantation chronosequence. In addition, we combined morphological methods and Illumina MiSeq sequencing techniques to analyze rhizosphere soil AMF. The results indicated that the AMF richness and diversity indexes of B. alnoides at two ages tended to be similar to those of natural growing trees in native forest. However, the specific AM fungal compositions were distinctly different, providing evidence of the conservation value of the native forest, which harbors a unique AMF diversity. Hierarchical cluster analysis further revealed that the AMF community composition of trees in the mid-aged stand (P12y) was more similar to that of naturally growing B. alnoides (N) than that of the young-aged trees (P3y), which proved the considerable resilience of AMF to the establishment of the B. alnoides plantation. A set of at least five soil properties (available phosphorus, available nitrogen, organic matter, total nitrogen and silt content) was found to play a significant role in shaping the AMF communities. These results contribute to the understanding of the impacts of B. alnoides plantations on AMF diversity and composition. Such information is critical for the efficient planting and sustainable management of B. alnoides plantations.