Ministry of Education Key Laboratory for Silviculture and Conservation, College of Forest Science, Beijing Forestry University Beijing, 100083, China ; Institute of Forestry and Climate Change Research, Beijing Forestry University Beijing, 100083, China.
State Forestry Administration of China Key Laboratory of Forest Ecology and Environment, Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry Beijing, 100091, China.
Ecol Evol. 2014 Mar;4(5):633-47. doi: 10.1002/ece3.969. Epub 2014 Feb 12.
Forest soils store vast amounts of terrestrial carbon, but we are still limited in mechanistic understanding on how soil organic carbon (SOC) stabilization or turnover is controlled by biotic and abiotic factors in forest ecosystems. We used phospholipid fatty acids (PLFAs) as biomarker to study soil microbial community structure and measured activities of five extracellular enzymes involved in the degradation of cellulose (i.e., β-1,4-glucosidase and cellobiohydrolase), chitin (i.e., β-1,4-N-acetylglucosaminidase), and lignin (i.e., phenol oxidase and peroxidase) as indicators of soil microbial functioning in carbon transformation or turnover across varying biotic and abiotic conditions in a typical temperate forest ecosystem in central China. Redundancy analysis (RDA) was performed to determine the interrelationship between individual PFLAs and biotic and abiotic site factors as well as the linkage between soil microbial structure and function. Path analysis was further conducted to examine the controls of site factors on soil microbial community structure and the regulatory pathway of changes in SOC relating to microbial community structure and function. We found that soil microbial community structure is strongly influenced by water, temperature, SOC, fine root mass, clay content, and C/N ratio in soils and that the relative abundance of Gram-negative bacteria, saprophytic fungi, and actinomycetes explained most of the variations in the specific activities of soil enzymes involved in SOC transformation or turnover. The abundance of soil bacterial communities is strongly linked with the extracellular enzymes involved in carbon transformation, whereas the abundance of saprophytic fungi is associated with activities of extracellular enzymes driving carbon oxidation. Findings in this study demonstrate the complex interactions and linkage among plant traits, microenvironment, and soil physiochemical properties in affecting SOC via microbial regulations.
森林土壤储存了大量的陆地碳，但我们对于生物和非生物因素如何控制土壤有机碳（SOC）的稳定或转化仍然缺乏机制上的理解。我们使用磷脂脂肪酸（PLFA）作为生物标志物来研究土壤微生物群落结构，并测量了参与纤维素（即β-1,4-葡萄糖苷酶和纤维二糖水解酶）、几丁质（即β-1,4-N-乙酰葡萄糖胺酶）和木质素（即酚氧化酶和过氧化物酶）降解的五种胞外酶的活性，作为土壤微生物在碳转化或周转过程中功能的指标，这些酶的活性在变化的生物和非生物条件下跨越中国中部典型温带森林生态系统。冗余分析（RDA）用于确定单个 PFLA 与生物和非生物站点因素之间的相互关系，以及土壤微生物结构和功能之间的联系。路径分析进一步用于检查站点因素对土壤微生物群落结构的控制，以及与微生物群落结构和功能相关的 SOC 变化的调节途径。我们发现，土壤微生物群落结构受到水、温度、SOC、细根质量、粘粒含量和土壤 C/N 比的强烈影响，革兰氏阴性菌、腐生真菌和放线菌的相对丰度解释了与 SOC 转化或周转相关的土壤酶特定活性变化的大部分变异。土壤细菌群落的丰度与参与碳转化的胞外酶密切相关，而腐生真菌的丰度与驱动碳氧化的胞外酶活性相关。本研究的结果表明，植物特性、微环境和土壤理化性质通过微生物调节相互作用和联系，影响 SOC。
