Hou Cui-Cui, Song Chang-Chun, Li Ying-Chen, Guo Yue-Dong
Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China.
Huan Jing Ke Xue. 2011 Jan;32(1):290-7.
The experiment was carried in Sanjiang Plain in the northeast of China during the growing season in 2009. Soil organic carbon (SOC), as well as the soil active organic carbon fractions in the 0-20 cm soil layer of Calamagrostis angustifolia wetland under different water conditions were on monthly observation. Based on the research and indoor analysis, the seasonal dynamics of light fractions of soil organic carbon (LFOC) and microbial biomass carbon (MBC) were analyzed. The results indicated that the SOC contents had significantly seasonal dynamics, and the hydrological circle had apparently driving effect on LFOC and MBC during the growing season, especially under the seasonal flooded condition. The freeze-thaw process reduced the SOC, LFOC, MBC contents, with the decreases of 74.53%, 80.93%, 83.09%, while both carbon contents of light and heavy fractions were reduced at the same time. The result also showed that the seasonal flooding condition increased the proportion of LFOC in topsoil, which was larger in marsh meadow (13.58%) than in wet meadow (11.96%), whilst the MBC in marsh meadow (1 397.21 mg x kg(-1)) was less than the latter (1 603.65 mg x kg(-1)), proving that the inundated environment inhibited the mineralization and decomposition of organic matter. But the microbial activity could be adaptive to the flooding condition. During the growing season the MBC soared to 1 829.21 mg x kg(-1) from 337.56 mg x kg(-1) in July, and the microbial quotient was 1.51 times higher than that in June, indicating the high microbial efficacy of soil organic matter. Meanwhile, there was a significant correlation between the contents of LFOC and SOC (r = 0.816), suggesting that higher LFOC content was favorable to the soil carbon accumulation. Moreover, in the seasonal flooded Calamagrostis angustifolia wetland the soil LFOC content was significantly correlated with MBC (r = 0.95), implying that the available carbon source had more severe restriction on the microbial activity under the flooding environment.
该实验于2009年生长季在中国东北的三江平原进行。对不同水分条件下小叶章湿地0-20厘米土层中的土壤有机碳（SOC）以及土壤活性有机碳组分进行了月度观测。基于研究和室内分析，分析了土壤有机碳轻组（LFOC）和微生物生物量碳（MBC）的季节动态。结果表明，SOC含量具有显著的季节动态，在生长季，水文循环对LFOC和MBC有明显的驱动作用，尤其是在季节性淹水条件下。冻融过程降低了SOC、LFOC、MBC含量，降幅分别为74.53%、80.93%、83.09%，同时轻、重组分的碳含量均降低。结果还表明，季节性淹水条件增加了表土中LFOC的比例，沼泽草甸（13.58%）高于湿草甸（11.96%），而沼泽草甸中的MBC（1397.21毫克·千克-1）低于后者（1603.65毫克·千克-1），证明淹水环境抑制了有机物的矿化和分解。但微生物活性能够适应淹水条件。在生长季，MBC从7月的337.56毫克·千克-1飙升至1829.21毫克·千克-1，微生物商数比6月高1.51倍，表明土壤有机质的微生物效率较高。同时，LFOC与SOC含量之间存在显著相关性（r = 0.816），表明较高的LFOC含量有利于土壤碳积累。此外，在季节性淹水的小叶章湿地中，土壤LFOC含量与MBC显著相关（r = 0.95），这意味着在淹水环境下，有效碳源对微生物活性的限制更为严重。
