Yang Yu Jing, Liu Shi Rong, Chen Lin, Wang Hui
State Forestry Administration Key Laboratory of Forest Ecology and Environment, Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China.
Experimental Center of Tropical Forestry, Chinese Academy of Forestry, Pingxiang 532600, Guangxi, China.
Ying Yong Sheng Tai Xue Bao. 2018 Jun;29(6):1779-1786. doi: 10.13287/j.1001-9332.201806.006.
To examine the effects of altered precipitation pattern on the mechanism of forest soil carbon (C) emission under climate change scenarios, we established plots with 50% reduction in throughfall in a subtropical Pinus massoniana plantation. The effects of throughfall reduction on the mineralization of both soil and aggregate-associated organic C were quantified by laboratory incubation at constant temperature. The results showed that the cumulative mineralization of organic C in the 1-2 mm aggregates was higher than that in other sizes of aggregates. In the dry and wet seasons, the surface soil water content in the throughfall reduction plots was 82.1% and 82.7% of that in the control, but the mass fractions of 0.106-0.25 mm soil aggregates in the throughfall reduction plots increased by 1.8% and 4.2% than the control, respectively. The throughfall reduction treatment significantly reduced the mineralization rate of labile C pools (k) of soil and micro-aggregates in the dry season, increased the mineralization rate of recalcitrant C pool (k) of soil and <1 mm aggregates, and had no significant effects on the cumulative mineralization of soil organic C. Results from the correlation analyses revealed significant and positive correlations between k of soil and that of the micro-aggregates and between k of soil and that of the 0.25-1 mm aggregates. Under the influence of aggregate structure, water condition and soil organic carbon content, the throughfall reduction suppressed the mineralization of labile organic C while stimulated that of recalcitrant organic C.
为研究气候变化情景下降水模式改变对森林土壤碳排放机制的影响，我们在亚热带马尾松人工林中设置了穿透雨减少50%的样地。通过恒温实验室培养，定量分析了穿透雨减少对土壤及与团聚体相关的有机碳矿化的影响。结果表明，1-2毫米团聚体中有机碳的累积矿化量高于其他粒径的团聚体。在旱季和雨季，穿透雨减少样地的表层土壤含水量分别为对照样地的82.1%和82.7%，但穿透雨减少样地中0.106-0.25毫米土壤团聚体的质量分数分别比对照样地增加了1.8%和4.2%。穿透雨减少处理显著降低了旱季土壤和微团聚体中易分解碳库的矿化速率（k），提高了土壤和<1毫米团聚体中难分解碳库的矿化速率（k），对土壤有机碳的累积矿化量无显著影响。相关性分析结果表明，土壤的k与微团聚体的k之间以及土壤的k与0.25-1毫米团聚体的k之间存在显著正相关。在团聚体结构、水分条件和土壤有机碳含量的影响下，穿透雨减少抑制了易分解有机碳的矿化，同时促进了难分解有机碳的矿化。
