喀斯特地区土壤丛枝菌根真菌群落对岩性和人工造林的响应

Responses of soil arbuscular mycorrhizal fungal communities to lithology and afforestation in karst region

明确丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)群落对岩性和人工造林的响应特征,是合理利用AMF改善喀斯特地区人工林土壤质量、提升造林效益的重要前提。本文以我国西南喀斯特地区石灰岩和碎屑岩区人工林为研究对象,并以耕地为对照,通过野外区域采样与室内分析相结合,采用高通量测序技术分析土壤AMF多样性和群落结构,探讨其对岩性和人工造林的响应。结果表明:球囊霉属(Glomus)为研究区主要优势属,其相对丰度为58.50%~89.37%。AMF群落对人工造林的响应在不同岩性条件下存在差异:在石灰岩区,人工造林显著增加了AMF香农多样性指数;在碎屑岩区,人工造林显著增加了球囊霉属相对丰度,却降低了近明球囊霉属(Claroideoglomus)和类球囊霉属(Paraglomus)的相对丰度。进一步分析发现,土壤pH和速效磷是影响AMF群落的关键环境因子。岩性主要通过影响土壤pH间接作用于AMF群落变化(p<0.05);而人工造林则通过改变土壤养分(特别是速效磷)对AMF群落起到直接或间接作用(p<0.05)。可见,人工造林对土壤AMF群落的影响受到地质背景(岩性)的制约,未来将AMF用于改善喀斯特地区人工林土壤质量时要充分考虑土壤岩性。

To clarify the response characteristics of arbuscular mycorrhizal fungal(AMF)community to lithology and afforestation is an important premise for rationally using AMF to improve the soil quality and afforestation efficiency of artificial forest in the karst region.Here,based on the soil samples from planted forests and farmlands were collected under both limestone and clasolite conditions,and the AMF community were analyzed by high-throughput sequencing to explore its response to lithology and afforestation.The results show that Glomus is identified as the dominant genus in the study area,and its average relative abundance ranges from 58.50%to 89.37%.The response of the AMF community to afforestation was different under these two lithological conditions.In the limestone area,afforestation significantly increased of the Shannon diversity index of AMF.In the clasolite condition,afforestation significantly increased the relative abundance of Glomus,but decreased the relative abundance of Claroideoglomus and Paraglomus.Further analysis revealed that soil pH and available phosphorus were the key environmental factors affecting the community of AMF under both lithology backgrounds.Lithology indirectly affected the AMF community through soil pH(p<0.05),while afforestation has both direct and indirect effects on AMF community by changing soil nutrients,especially decreasing the available phosphorus(p<0.05).Therefore,the effect of artificial afforestation on soil AMF community is restricted by geological background(lithology),and the lithology should be fully considered when using AMF to improve soil quality of artificial forest in karst areas in the future.