Controls on microbially regulated soil organic carbon decomposition at the regional scale
Controls on microbially regulated soil organic carbon decomposition at the regional scale
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DOI：
10.1016/j.soilbio.2017.12.007
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发表时间：
2018-03
影响因子：
9.7
通讯作者：
Rana Shahbaz Ali;E. Kandeler;S. Marhan;M. S. Demyan;J. Ingwersen;Reza Mirzaeitalarposhti;F. Rasche
中科院分区：
文献类型：
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作者：
Rana Shahbaz Ali;E. Kandeler;S. Marhan;M. S. Demyan;J. Ingwersen;Reza Mirzaeitalarposhti;F. Rasche
在区域尺度上，即使土壤有机碳（SOC）微生物分解速率的微小变化也有可能改变全球尺度上的陆-气反馈。对微生物驱动过程的调控了解有限，导致全球SOC估计存在重大不确定性。因此，为了更好地理解控制SOC动态的大尺度过程，我们在两个尺度上研究了SOC数量、质量和土壤理化性质对土壤基础呼吸的影响，以及土壤呼吸和酶（β-葡萄糖苷酶和木聚糖酶）的温度敏感性（Q10）：景观（两个单独的区域，每个区域约27 km 2）和区域（两个区域的合并数据）。土壤样品（0-30厘米土壤深度）来自41个农业点，分布在德国西南部的两个地区，不同的气候和地质条件。我们使用了两步数据分析程序;通过随机森林回归进行变量选择，然后使用线性混合效应模型筛选重要的解释变量。微生物生物量调节土壤基础呼吸在这两个尺度上，而土壤C：N比发挥了重要作用，只有在区域尺度上的混合效应模型的基础上。土壤质地显著解释了两种尺度下土壤呼吸的温度敏感性（Q10）。不同的SOC质量分数midDRIFTS特征发挥了次要作用，而可提取的有机碳负相关的呼吸Q10。控制土壤酶（Q10）的土壤性质具有尺度特异性。在景观尺度上，pH是影响β-葡萄糖苷酶Q10的主要因子。我们认为，规模特异性的变量可能取决于同质性的研究领域，并应考虑在探索SOC动态。本研究确定了影响土壤基础呼吸及其温度敏感性的直接和间接控制因子，为大尺度SOC动态研究提供了重要信息。
Even small changes in microbial decomposition rates of soil organic carbon (SOC) at the regional scale have the potential to modify land-atmospheric feedbacks at the global scale. Limited understanding of the regulation of microbial driven processes has led to major uncertainty in global SOC estimates. Therefore, to better understand the large scale processes controlling SOC dynamics, we examined the influence of SOC quantity, quality, and soil physical and biochemical properties on soil basal respiration and of the temperature sensitivities (Q10) of soil respiration and enzymes (β-glucosidase and xylanase) at two scales: landscape (two individual areas, each approximately 27 km2) and regional (pooled data of both areas). Soil samples (0–30 cm soil depth) originated from 41 agricultural sites distributed over two areas in southwest Germany differing in climatic and geological conditions. We used a two-step data analysis procedure; variable selection through random Forest regression, followed by shortlisting of significant explanatory variables using linear mixed-effect models. Microbial biomass regulated soil basal respiration at both scales, whereas soil C:N ratio played an important role only at the regional scale based on mixed-effect models. Soil texture significantly explained temperature sensitivity (Q10) of soil respiration at both scales. Different SOC quality fractions characterized by midDRIFTS played a minor role, whereas extractable organic C related negatively to the respiration Q10. Soil properties controlling soil enzymes (Q10) were scale-specific. We found pH to be the main factor affecting β-glucosidase Q10at the landscape scale. We argue that scale-specificity of variables may depend on homogeneity of study areas and should be considered when exploring SOC dynamics. Our study identified direct and indirect controlling factors affecting soil basal respiration and its temperature sensitivity, providing vital information for SOC dynamics at large scales.