Predominant control of moisture on soil organic carbon mineralization across a broad range of arid and semiarid ecosystems on the Mongolia plateau
Predominant control of moisture on soil organic carbon mineralization across a broad range of arid and semiarid ecosystems on the Mongolia plateau
复制标题
蒙古高原干旱和半干旱生态系统中水分对土壤有机碳矿化的主导控制
DOI：
10.1007/s10980-014-0040-0
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发表时间：
2015-11-01
影响因子：
5.2
通讯作者：
Bai, Yongfei
中科院分区：
文献类型：
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作者：
Mi, Jia;Li, Jianjun;Bai, Yongfei
已知土壤湿度和温度是调节土壤有机碳（SOC）矿化的两个环境约束。然而，目前尚不清楚水分、温度和其他非生物和生物因素在多大程度上影响广泛地理区域的 SOC 矿化。在这里，我们采用短期实验室孵化（28天）、实地调查和结构方程模型（SEM）相结合的综合方法，研究了蒙古高原12个广泛分布的干旱和半干旱生态系统中多种非生物和生物因素对SOC矿化的影响。我们的结果表明，土壤湿度对所有地点的 SOC 矿化具有主要控制作用。所有地点的平均二氧化碳排放量从 30% 到 60% 充水孔隙空间 (WFPS) 增加了 23%，从 60% 到 90% WFPS 增加了 176%。在 25 °C 和 60% WFPS 的条件下，表土（0–20 cm）中累积 CO2–C 排放量按以下顺序减少：草甸草原（227 mg kg−1）> 典型草原（216 mg kg−1）> 沙漠（99 mg kg−1）> 荒漠草原（72 mg kg−1）。 SOC矿化（Q10）的温度敏感性（Q10），即10°C温度梯度下碳矿化速率的比例变化，在低温高湿条件下最高，但在高温低湿条件下最低。 SEM 分析表明，SOC 的矿化潜力似乎直接受微生物活动和底物可用性的调节。调节 SOC 和微生物生物量碳含量的气候因素（如年平均降水量、年平均温度）、地上和地下生物量以及土壤 pH 值也间接影响 SOC 矿化。我们的研究结果表明，全球气候变化，特别是极端风暴和干旱频率的增加，将严重影响干旱和半干旱地区的SOC矿化和生态系统碳循环。
Soil moisture and temperature are known to be the two environmental constraints regulating mineralization of soil organic carbon (SOC). However, it remains unclear to what extent the moisture, temperature, and other abiotic and biotic factors affect the mineralization of SOC across broad geographic regions. Here, we examined the effects of multiple abiotic and biotic factors on SOC mineralization across 12 widespread arid and semiarid ecosystems on the Mongolia plateau, by using an integrative approach combining short-term laboratory incubations (28-day), field survey, and structure equation modeling (SEM). Our results showed that soil moisture had a predominant control on SOC mineralization across all sites. The average CO2emissions over all sites increased by 23 % from 30 to 60 % water filled pore space (WFPS) and by 176 % from 60 to 90 % WFPS. Under conditions of 25 °C and 60 % WFPS, the cumulative CO2–C emissions in the topsoil (0–20 cm) diminished in the following order: meadow steppe (227 mg kg−1) > typical steppe (216 mg kg−1) > desert (99 mg kg−1) > desert steppe (72 mg kg−1). The temperature sensitivity of SOC mineralization (Q10), the proportional change in carbon mineralization rate given a 10 °C temperature gradient, was highest under conditions of low temperature and high moisture, but it was lowest under high temperature and low moisture. The SEM analyses demonstrate that the mineralization potential of SOC seems to be directly regulated by microbe activity and substrate availability. Climatic factors (e.g. mean annual precipitation, mean annual temperature), above- and belowground biomass, and soil pH, which regulate SOC and microbial biomass carbon content, also indirectly influence the SOC mineralization. Our results indicate that global climate change, particularly the increase in the frequency of extreme storms and droughts, will substantially affect SOC mineralization and ecosystem carbon cycle in arid and semiarid regions.