No temperature acclimation of soil extracellular enzymes to experimental warming in an alpine grassland ecosystem on the Tibetan Plateau
No temperature acclimation of soil extracellular enzymes to experimental warming in an alpine grassland ecosystem on the Tibetan Plateau
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DOI：
10.1007/s10533-013-9844-2
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发表时间：
2014-01-01
期刊：
影响因子：
4
通讯作者：
He, Jin-Sheng
中科院分区：
文献类型：
--
作者：
Jing, Xin;Wang, Yonghui;He, Jin-Sheng
高寒草地土壤储存着大量的有机碳，且易受气温升高的影响。土壤胞外酶是土壤有机碳分解的限速步骤，其催化、产生和降解速率受温度的调控。因此，这些酶对变暖的响应可能对高寒草地生态系统的碳循环产生深远的影响。研究了青藏高原高寒草地生态系统土壤胞外酶活性和温度敏感性（Q（10））对升温的响应。2006年5月建立了一个免费的空气温度提高系统。在2009年和2010年，我们测量了土壤微生物生物量，养分有效性和五种胞外酶的活性。使用简单的一阶指数方程计算每种酶的Q（10）。我们发现，变暖对土壤微生物生物量C，不稳定的C或N含量，或养分有效性没有显着影响。在大多数胞外酶的活性之间的采样日期的显着差异被发现，通常较高的酶活性在温暖的一年。在20 A ℃时，升温对5种胞外酶活性的影响不显著。在体外酶活性强烈增加的温度高达27摄氏度或超过30摄氏度（最佳温度; T-opt）。Q（10）存在季节变化，但变暖对Q（10）的影响不显著。我们的结论是，土壤胞外酶适应季节性温度变化，但没有驯化田间实验变暖。
Alpine grassland soils store large amounts of soil organic carbon (SOC) and are susceptible to rising air temperature. Soil extracellular enzymes catalyze the rate-limiting step in SOC decomposition and their catalysis, production and degradation rates are regulated by temperature. Therefore, the responses of these enzymes to warming could have a profound impact on carbon cycling in the alpine grassland ecosystems. This study was conducted to measure the responses of soil extracellular enzyme activity and temperature sensitivity (Q(10)) to experimental warming in samples from an alpine grassland ecosystem on the Tibetan Plateau. A free air-temperature enhancement system was set up in May 2006. We measured soil microbial biomass, nutrient availability and the activity of five extracellular enzymes in 2009 and 2010. The Q(10) of each enzyme was calculated using a simple first-order exponential equation. We found that warming had no significant effects on soil microbial biomass C, the labile C or N content, or nutrient availability. Significant differences in the activity of most extracellular enzymes among sampling dates were found, with typically higher enzyme activity during the warm period of the year. The effects of warming on the activity of the five extracellular enzymes at 20 A degrees C were not significant. Enzyme activity in vitro strongly increased with temperature up to 27 A degrees C or over 30 A degrees C (optimum temperature; T-opt). Seasonal variations in the Q(10) were found, but the effects of warming on Q(10) were not significant. We conclude that soil extracellular enzymes adapted to seasonal temperature variations, but did not acclimate to the field experimental warming.