温带亚高山针叶林土壤碳循环微生物群落的时空动态

选取参与碳固定的二磷酸羧化/加氧酶基因（cbbM）、有机碳降解的淀粉酶基因（amylase）和纤维素酶基因（cellulase）作为分子标记，用实时定量PCR方法对温带亚高山华北落叶松（Larix gmelinii var.principis-rupprechtii）林、白杄（Picea meyeri）林、青杄（P.wilsonii）林和油松（Pinus tabulaeformis）林土壤碳循环功能微生物类群丰度的时空动态开展研究.结果显示，总碳（TC）、总氮（TN）、总硫（TS）、有机质（OM）和有机碳（TOC）、pH值、铵态氮（NH₄⁺-N）、硝态氮（NO₃^--N）、过氧化氢酶、蔗糖酶和脲酶活性在4种森林土壤中都有不同程度的差异，且有显著的季节变化特征.高海拔华北落叶松林土壤TC、TN、TS、C/N、OM和TOC含量最高，而pH值最低.土壤TC、TN、亚硝态氮（NO₂^--N）含量、蔗糖酶和脲酶活性，与碳循环微生物类群的丰度呈极显著相关.土壤NO₃^--N含量与有机碳分解和固碳微生物类群的相对丰度显著相关；土壤C/N、NO₂^--N、pH值、OM、TOC、过氧化氢酶及脲酶活性，与降解易分解碳（labile C）和难分解碳（recalcitrant C）的微生物类群的相对丰度呈极显著相关.植被类型和季节变化共同影响土壤碳循环微生物类群的丰度，而季节变化是主导因素.植被和土壤环境因子通过调控微生物群落碳代谢功能类群的结构，影响森林土壤碳源-汇的平衡.

Spatiotemporal dynamics of microbial communities involved in soil carbon cycling of subalpine temperate coniferous forest

The cbbM, amylase and cellulase genes were selected as molecular markers to analyze functional microbial groups using real-time quantitative PCR method. We investigated the spatiotemporal dynamics of abundance of functional microbial groups in soils of four forests:Larix gmelinii var. principis rupprechtii, Picea meyeri, P. Wilsonii and Pinus tabulaeformis in subalpine temperate of north China. The results indicated that soil content of total carbon (TC), total nitrogen (TN), total sulfur (TS), organic matter (OM) and total organic carbon (TOC), pH, ammonium nitrogen (NH₄⁺-N), nitrate nitrogen(NO₃^--N), and the activities of catalase, sucrase and urease were different in the soil of four forests, and exhibited seasonal dynamics variation. The contents of TC, TN, TS, C/N, OM and TOC were the highest, but pH value was the lowest in the higher altitude L. principis forest soil. The contents of TC, TN, nitrite nitrogen (NO₂^--N), sucrase activity and urease activity were significantly correlated with the abundance of microbial groups involving in carbon fixation, starch degradation and cellulose degradation. The content of NO₃^--N in soil was significantly related to the relative abundance of carbon decomposing and carbon fixing microorganisms. Soil C/N, NO₂^--N, OM, TOC content, pH, catalase and urease activity were significantly correlated with the relative abundance of microbial groups involving in degradation of labile carbon and recalcitrant carbon. Vegetation type and seasonal change jointly affected the abundance of soil functional microbial groups, but seasonal change was the dominant factor. The vegetation and soil environmental factors affected the carbon source-sink balance of forest soil by regulating the structure of carbon metabolism functional groups of microbial community.