喀斯特高钙生境中AM真菌对土壤稳定性有机碳的调控与储存

The Soil carbon pool in the Karst regions is of great importance for the global carbon budget. However, the mechanisms of the carbon cycling in the Karst ecosystems responding to the global changes remain unclear and it is essential to investigate how arbuscular mycorrhizae (AM) fungi regulate the stable carbon storage in the Karst habitats with high calcium. The separation techniques of mycelium and root by compartment separation will be utilized in this experiment. The litter，CO2 and CaCO3 marked with 13C will be added into the soil. The following is to be studied: (1) The effects of AM fungi on soil organic matter decomposition and the storage of stable organic carbon in soil aggregates. (2) The effects of AM fungi on transfer of soil C-CaCO3 and atmosphere carbon. (3) Regulation of AM fungi on the biochemical processes in the Plant-Soil systems. Two hypothesis are to be tested that “High calcium content enhances the decomposition of litter and storage of stable organic carbon by AM mycelium” and “AM fungi stores stable organic carbon from atmosphere CO2 and soil calcium carbonate” The study will reveal the role of AM fungi to regulate soil stable organic carbon of the Karst area with high calcium content and contribute to insight into the mechanisms of how Karst ecosystems respond to global changes via adaptation of AM.fungi.

喀斯特生态系统是重要的碳库，探索喀斯特高钙生境中AM真菌是如何调控碳的稳定储存，对揭示该系统响应全球变化的碳循环机制具有重要意义。本项目采用分室系统模拟控制试验，采用菌丝分离技术和13C标记技术对枯落物、CO2和碳酸钙中的碳进行标记。检测土壤中稳定性团聚体的结构和数量、不同粒径团聚体的δ13C值和GRSP含量及植物-土壤体系中的其他生理、生化指标，研究（1）高钙生境中AM对土壤有机物的分解和土壤团聚体稳定性有机碳储存；（2）AM真菌对碳酸钙碳和大气碳的转运和土壤团聚体稳定性有机碳储存的影响；（3）AM真菌调控高钙生境中植物-土壤体系生化过程。验证假说“喀斯特高钙含量促进AM真菌对有机物的分解和稳定性有机碳的储存”和“AM真菌以稳定性有机碳方式储存大气碳和碳酸钙碳”，探索在高钙条件下AM真菌调控土壤C的转移途径和C储存机制，阐明喀斯特斯特生态系统响应全球变化的菌根适应调控策略。

石漠化是制约喀斯特地区社会经济发展的关键问题，丛枝菌根（AM）真菌对植物生长和营养利用具有较大的促进作用，在全球CO2浓度升高背景下，菌根真菌对喀斯特土壤碳的储存和植被固碳功能还不清楚，限制了菌根生物技术应用于喀斯特生态修复的碳汇造林的应用。本项目从丛枝菌根真菌转移和固定稳定性碳的机制研究入手，探索AM真菌对土壤碳、植物碳、碳酸钙碳的转移途径和储存过程，项目研究了AM与土壤碳酸钙对植物固碳的影响，AM与碳酸钙的交互作用对植物氮磷养分利用的影响，AM和碳酸钙交互作用对土壤碳、土壤球囊霉素、土壤有机质的影响，初步揭示了喀斯特高钙生境中丛枝菌根对喀斯特植物生物固碳和土壤固碳的储存机制等。该项目成果奠定和丰富了喀斯特植物通过菌根真菌调控碳存储的基础理论，为喀斯特植被恢复中采用菌根生物技术固碳具有一定的指导意义。