Simulated rain addition modifies diurnal patterns and temperature sensitivities of autotrophic and heterotrophic soil respiration in an arid desert ecosystem
Simulated rain addition modifies diurnal patterns and temperature sensitivities of autotrophic and heterotrophic soil respiration in an arid desert ecosystem
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DOI：
10.1016/j.soilbio.2014.12.020
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发表时间：
2015-03
影响因子：
9.7
通讯作者：
Weimin Song;Shiping Chen;Bo Wu;Yajuan Zhu;Yadan Zhou;Q. Lu;G. Lin
中科院分区：
文献类型：
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作者：
Weimin Song;Shiping Chen;Bo Wu;Yajuan Zhu;Yadan Zhou;Q. Lu;G. Lin
干旱和半干旱地区降雨事件的时间和规模预计将在未来几十年发生巨大变化，这可能会极大地影响区域碳循环。为了解降雨量增加对土壤呼吸及其关键组分（异养呼吸和自养呼吸）的日变化和温度敏感性（Q10）的影响，在中国西北荒漠生态系统中进行了人工模拟试验。我们模拟了五种不同的情况下，未来的降雨制度（0%，25%，50%，75%和100%的增加当地年平均降水量），每个月从2009年5月至9月。在增雨后的第6天和第16天，每隔3小时测量一次RS和RH，并通过计算RS和RH之差来估计RA，发现增雨显著增加了生长季内两个测量日的日平均RS及其分量。但两种呼吸分量的日变化规律不同。雨水增加显著增加了RH的每日Q10值，但抑制了第6天的RA。在土壤含水量较低的第16天，降雨对两种呼吸组分的日Q10值均无影响。另外，在5种降雨处理下，RH的Q10值均显著高于RA，表明在短时间尺度内，微生物呼吸比根系呼吸对温度更敏感。因此，将土壤呼吸分解为两个分量，并分析其对未来气候变化的差异响应，可以更准确地预测干旱半干旱地区的土壤呼吸和区域碳循环。
The timing and magnitude of rainfall events in arid and semiarid regions are expected to change dramatically in future decades, which will likely greatly affect regional carbon cycles. To understand how increases in rainfall affect the diurnal patterns and temperature sensitivities (Q10) of soil respiration (RS) and its key components (i.e. heterotrophic respiration (RH) and autotrophic respiration (RA)), we conducted a manipulative field experiment in a desert ecosystem of Northwest China. We simulated five different scenarios of future rain regimes (0%, 25%, 50%, 75% and 100% increase over local annual mean precipitation) each month from May to September in 2009. We measured RSand RHevery three hours on 6 and 16 days after the rain addition, and estimated RAby calculating the difference between RSand RH.We found that rain addition significantly increased the daily mean RSand its components on the two measurement days during the growing season. However, the diurnal pattern was different between the two respiration components. Rain addition significantly increased the daily Q10value of RHbut suppressed that of RAon Day 6. Rain addition had no influence on daily Q10value of both respiration components on Day 16 when soil moisture was lower. In addition, we observed significantly higher daily Q10of RHthan RAunder all five rain addition treatments, indicating that microbial respiration is more temperature sensitive than root respiration in a short-time scale in this desert ecosystem. Thus, partitioning soil respiration into its two components, and analyzing the differential responses of RHand RAto future climate changes should be considered for more accurate predictions of soil respiration and regional carbon cycle in these arid and semiarid regions.