In situ short-term dynamics of CO2 flux and microbial biomass after simulated rainfall in dry croplands in four tropical and continental ecosystems
In situ short-term dynamics of CO2 flux and microbial biomass after simulated rainfall in dry croplands in four tropical and continental ecosystems
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DOI：
10.1080/00380768.2015.1018800
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发表时间：
2015-03
影响因子：
2
通讯作者：
S. Sugihara;Shinya Funakawa;A. Kadono;Y. Takata;Kozue Sawada;K. Fujii;T. Kosaki
中科院分区：
文献类型：
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作者：
S. Sugihara;Shinya Funakawa;A. Kadono;Y. Takata;Kozue Sawada;K. Fujii;T. Kosaki
在零星降雨为主的旱地，土壤干湿循环主要驱动碳(C)动态。为了揭示四种不同气候和生态系统下单次降雨对粘土旱地土壤碳动态的影响，我们评估了土壤二氧化碳（CO2）外排和微生物生物量的原位短期（小时）动态，比较了有/无C基质的单次降雨事件的重要性。试验在热带气候条件下的泰国（TH）和坦桑尼亚（TZ）以及大陆性气候条件下的哈萨克斯坦（KZ）和匈牙利（HG） 4个粘土旱地进行。在模拟降雨（W样区）和降雨/葡萄糖（WG样区）处理后，每小时测量土壤CO2外排、原位微生物生物量（MB）和原位微生物活性（qCO2）。我们还用培养法对易矿化碳（EMC）进行了评价。降雨处理增加了qCO2，但没有增加MB，导致所有W样地的碳冲洗明显但时间较短（10-37 h），而WG处理增加了qCO2和MB，导致WG样地的碳冲洗时间更长且更大（约100 h）。降雨处理引起的累积土壤CO2通量与EMC的比值在TH-W和TZ-W地块（分别为8.2和4.9%）大于KZ-W和HG-W地块（分别为2.9和1.1%）。此外,应用葡萄糖是TH-WG更多矿化和TZ-WG情节(分别为9.7%和15.0)比在KZ-WG HG-WG情节(分别为3.4%和6.4),因为不同的MB增加模式的第一个24小时,也就是说,立即和大型MB增量在TH和TZ,但不是在KZ和HG。这些结果揭示可能的机制,导致土壤有机碳和应用的快速分解有机物质在干燥的热带农田。
Abstract The wet–dry cycles of soil primarily drive carbon (C) dynamics in dry croplands that mainly experience sporadic rainfall events. We evaluated the in situ short-term (hourly) dynamics of soil carbon dioxide (CO2) efflux and microbial biomass, to compare the significance of a single rainfall event with/without C substrate to reveal the effects of a single rainfall on the soil C dynamics in clayey dry croplands in four different climates and ecosystems. The experiments were conducted on four clayey dry croplands as follows: Thailand (TH) and Tanzania (TZ) in tropical climates, and Kazakhstan (KZ) and Hungary (HG) in continental climates. Hourly measurements of soil CO2 efflux, in situ microbial biomass (MB) and in situ microbial activity (qCO2) were conducted after the application of simulated rainfall (W plots) and rainfall/glucose (WG plots) treatments. We also evaluated the easily mineralizable carbon (EMC) by incubation. The rainfall treatment caused an increase in the qCO2 but not in MB, causing a clear but short C flush in all W plots (10–37 h), while the WG treatment caused an increase both of qCO2 and MB, resulting in substantially longer and larger C flush in the WG plots (ca. 100 h). The ratio of the cumulative soil CO2 flux caused by rainfall treatment to EMC was larger in TH-W and TZ-W plots (8.2 and 4.9%, respectively) than in the KZ-W and HG-W plots (2.9 and 1.1%, respectively). In addition, applied glucose was more heavily mineralized in the TH-WG and TZ-WG plots (15.0 and 9.7%, respectively) than in the KZ-WG and HG-WG plots (6.4 and 3.4%, respectively), because of the different MB increment patterns for the first 24 h, i.e., immediate and large MB increments in TH and TZ, but not in KZ and HG. These results reveal a possible mechanism that causes the rapid decomposition of soil organic carbon and applied organic matter in the dry tropical cropland.