Absence of thermal adaptation to ambient temperature in soil extracellular enzymes: Evidence from temperate grasslands across a regional scale
Absence of thermal adaptation to ambient temperature in soil extracellular enzymes: Evidence from temperate grasslands across a regional scale
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DOI：
10.1016/j.soilbio.2021.108540
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发表时间：
2021-12
影响因子：
9.7
通讯作者：
Ya-Juan Deng;Xinyue Chen;Xiaodong Yao;Lizheng Dong;Hongjin Zhang;H. Zeng;Wei Wang
中科院分区：
文献类型：
--
作者：
Ya-Juan Deng;Xinyue Chen;Xiaodong Yao;Lizheng Dong;Hongjin Zhang;H. Zeng;Wei Wang
土壤有机质分解速率与土壤环境的年平均温度有关，具有热适应性。这可能是因为参与分解的土壤胞外酶对温度敏感。本研究的目的是确定土壤胞外酶活性及其温度敏感性（以Q10测量）是否与草原地区的年平均温度有关。我们在中国北方沿纬度梯度的57个温带草地样地收集了表层土壤（0 ~ 10 cm）。测定土壤胞外酶（β-1,4-葡萄糖苷酶、β-1,4- n乙酰氨基葡萄糖苷酶、亮氨酸氨基肽酶和酸性磷酸酶）在5℃、15℃、25℃和35℃4种检测温度下的q10。在控制其他影响因子（土壤pH、底物、质地）的情况下，年平均温度与标准化胞外酶活性之间不存在相关性，说明胞外酶活性不存在热适应性。土壤pH、基质和质地等土壤土壤因子比年平均温度更能解释标准化胞外酶活性的空间变化。4种酶的q10值均随年平均温度的升高而显著升高，但在最高活性时趋于一致，β-1,4-葡萄糖苷酶的q10值均值为1.17,β-1,4- n乙酰氨基葡萄糖苷酶为1.21，亮氨酸氨基肽酶为1.11，酸性磷酸酶为1.08。胞外酶活性q10与年平均温度的正相关关系不符合热力学理论，预测年平均温度越低，q10位点越高。这可能是由于细胞外酶在生物细胞外工作，因此与微生物生物量的生理过程速率没有直接关系。本研究有助于我们了解土壤胞外酶的热适应性，并表明年平均气温较低的草地并不一定具有较高的胞外酶温度敏感性。
Soil organic matter decomposition rates are thermally adapted, in relation to the ambient mean annual temperature of the soil environment. This could be because of temperature sensitivity of soil extracellular enzymes involved in decomposition. The objective of this study was to determine if soil extracellular enzyme activity and its temperature sensitivity (measured as Q10) were related to the mean annual temperature across a grassland region. We collected surface soil (0-10 cm) from 57 temperate grassland sites along a latitudinal gradient in northern China. The Q10of soil extracellular enzymes (β-1,4-glucosidase, β-1,4-N acetylglucosaminidase, leucine aminopeptidase and acid phosphatase) was measured at four assay temperatures (5 °C, 15 °C, 25 °C, and 35 °C). There was no relationship between the mean annual temperature and standardized extracellular enzyme activity when other influential factors (soil pH, substrates, texture) were controlled, implying no thermal adaption of extracellular enzyme activity. Soil edaphic factors like soil pH, substrates and texture explained more of the spatial variation in the standardized extracellular enzyme activity than the mean annual temperature. Although the Q10of all four enzymes increased significantly with mean annual temperature, the data converged at the maximum activity, and the average Q10values were 1.17 for β-1,4-glucosidase, 1.21 for β-1,4-N acetylglucosaminidase, 1.11 for leucine aminopeptidase and 1.08 for acid phosphatase. The positive correlation between the Q10of extracellular enzyme activity and mean annual temperature is not consistent with the thermodynamic theory, which predicts higher Q10at sites with lower mean annual temperature. This may be due to the fact that extracellular enzymes operate outside of biological cells and thus are not directly related to physiological process rates of the microbial biomass. This study contributes to our understanding of the thermal adaptation of soil extracellular enzymes, and show that grassland sites with lower mean annual temperature do not necessarily induce higher temperature sensitivity of extracellular enzymes.