小兴安岭两种森林类型土壤有机碳矿化的季节动态

Seasonal dynamics of soil organic carbon mineralization for two forest types in Xiaoxing'an Mountains,China

采用室内培养法测定小兴安岭原始阔叶红松林、杨桦次生林不同季节的土壤有机碳(SOC)矿化速率和累计矿化量(C_m),利用一级动力学方程对土壤易矿化有机碳(C_1)、潜在可矿化碳(C_0)等参数进行拟合,并分析C_m、C_0与土壤环境因子的关系.结果表明:2种森林类型土壤有机碳培养矿化速率和C_m的季节变化趋势一致,在0~5 cm土层随季节推进而减小,在5~10 cm土层未表现出明显的季节差异;C_1在0~5和5~10 cm土层分别为42.92~92.18和19.23~32.95 mg·kg^(-1),C_0在0~5和5~10 cm土层分别为863.92~3957.15和434.15~865.79mg·kg^(-1),C_1和C_0均随季节推进而减小.2种森林类型土壤C_0/SOC在0~5和5~10 cm土层分别为0.74%~2.78%和1.11%~1.84%.C_0/SOC随季节推进而减小,表明从春季至秋季土壤有机碳含量总体上趋于稳定.土壤C_m和C_0与原位土壤湿度、热水浸提碳水化合物含量呈显著正相关,而与原位土壤温度、冷水浸提碳水化合物含量的相关性不显著.土壤有机碳矿化的季节动态受土壤环境因素和活性碳组分等综合作用的影响.

To investigate the seasonal dynamics of soil organic carbon（SOC） mineralization in Xiaoxing＇ an Mountain,we incubated soil samples collected from virgin Korean pine forest and broad-leaved secondary forest in different seasons in the laboratory and measured the SOC mineralization rate and cumulative SOC mineralization（Cm）.We employed simultaneous reaction model to describe C mineralization kinetics and estimated SOC mineralization parameters including soil easily mineralizable C（C1）,potentially mineralizable C（C0）.We also analyzed the relations between Cm,C1 and their influencing factors.Results showed that the incubated SOC mineralization rate and Cm for 0-5 cm soil layer decreased from early spring to late autumn,while for 5-10 cm soil layer the seasonal variation was not statistically significant for both forest types.The C1 in 0-5 and 5-10 cm soil layers varied from 42.92-92.18 and 19.23-32.95 mg·kg^-1,respectively,while the C0 in0-5 and 5-10 cm soil layers varied from 863.92-3957.15 and 434.15-865.79 mg·kg^-1,respectively.Both C1 and C0 decreased from early spring to late autumn.The proportions of C0 in SOC for two forest types were 0.74%-2.78%and 1.11%-1.84%in 0-5 and 5-10 cm soil layers,respectively,and decreased from early spring to late autumn,indicating that SOC tended to become more stable as a whole from spring to autumn.The Cm and C0 were significantly positively correlated to in situ soil water content and hot water-extractable carbohydrate content,but were not correlated to in situ soil temperature and cool water-extractable carbohydrate content.We concluded that soil labile organic carbon,soil physical and chemical properties contributed to the seasonal dynamics of SOC mineralization in the forests.