苏北不同林龄杨树林土壤活性碳的季节变化

土壤活性有机碳是全球碳循环中的最为活跃的重要组成部分。为阐明苏北沿海杨树人工林土壤活性有机碳季节变化特征及其主要影响因子,选择不同林龄(4、8、12、15、20a)的杨树人工林,研究了0～10、10～25和25～40cm土层水溶性有机碳、微生物生物量碳及土壤温度、湿度等生态因子的季节动态变化。结果表明:不同林龄的杨树林土壤水溶性有机碳和土壤微生物生物量碳总体上表现为春夏季节大于秋冬季节,且均以0～10cm土层变化差异最显著;土壤水溶性有机碳最大值出现在春季,最小值在秋季;土壤微生物生物量碳最大值在夏季,最小值在秋季或冬季。相关关系分析表明,土壤水溶性有机碳含量和微生物生物量碳之间具有显著的相关关系,2种活性碳与土壤温湿度的相关关系不显著。研究表明,土壤活性碳的季节变化不仅受到温湿度季节变化的影响,还受到土壤理化性质、地被特征及其季节变化等因素的综合影响。

Seasonal variation patterns of soil labile organic carbon in poplar plantations with different ages in northern Jiangsu

Soil labile organic carbon is the most active and important component in the global carbon cycle. To understand the seasonal variations of soil labile organic carbon and their main controlling factors in the poplar (Populus euramericana cv. I-72) plantations in coastal area of northern Jiangsu, five poplar plantations of 4-, 8-, 12-, 15- and 20-years old were selected as study sites, with the water-soluble organic carbon (WSOC), microbial biomass carbon (MBC), temperature, and moisture in 0-10, 10-25, and 25-40 cm soil layers determined. Overall, the soil WSOC and MBC in the plantations were higher in spring and summer, but lower in autumn and winter, especially in 0-10 cm soil layer. The WSOC was the maximum in spring and the minimum in autumn, while the MBC was the maximum in summer and the minimum in autumn or winter. The WSOC was significantly correlated with the MBC, but the WSOC and MBC had less correlation with soil temperature and soil moisture. The seasonal variations of the WSOC and MBC were not only affected by the seasonal variations of soil temperature and soil moisture, but also affected by the soil physical and chemical properties and the seasonal changes of ground cover.