黄土丘陵区典型人工林有机碳分布特征及其影响因素

Distribution Characteristics of Soil Organic Carbon and Their Affecting Factors of Typical Plantations in Loess Hilly Region

分析了黄土丘陵区典型人工林刺槐、沙棘和柠条0—60cm土层土壤有机碳(SOC)储量及分布特征的差异,研究了不同类型人工林随生长年限的增加对SOC产生的影响。结果表明,人工林建造对SOC积累具有积极作用,各人工林进入生长稳定期后,对SOC有一定补给作用,有机碳补给能力表现为:沙棘>刺槐>柠条,这种差异因根系生长特点不同产生,沙棘主要在20—40cm土层,年平均补给量为0.357g/kg;刺槐和柠条为40—60cm,年平均补给量分别为;0.010和0.005g/kg。回归分析结果表明,土壤物理性状与SOC含量相关性显著(p<0.01),SOC含量随土壤容重增大而减小,随团聚体稳定性增大而增大,相关系数分别为-0.82和0.79。

In order to understand the effects of different plantation types on soil organic carbon accumulation, we conducted a comparative analysis on the variations in the total amount and distribution characteristics of soil organic content in the 0-60 cm soil layers of typical plantations of Robinia pseudoacacia, Hippophae rhamnoides, Caragana intermedia in the loess hilly region. The results showed that the plantations played positive roles in soil organic carbon accumulation. After reaching their stable growth stages, the plantations showed replenishment effects on the soil organic carbon pool. The replenishment ability of the plantations could be ranked in a decending order as Hippophae rhamnoides^Robinia pseudoacada ~Caragana interme- dia, with average annual replenishment rates of 0. 854, 0. 004 and 0. 003 g, respectively. Owing to the differences in root growth distribution, the replenishment rates varied vertically for different plantations. Under the plantation of Hippophae rhamnoides, the increase of soil carbon mainly occurred at the 20--40 cm layer with an annual replenishment rate of 0. 357 g, while for Robinia pseudoacada and Caragana intermedia, the increases were found at the layers of 40--60 cm with rates of 0. 010 and 0. 005 g/kg, respectively. Moreover, the results also indicated significant correlation between soil physical properties and soil organic content（p〈0.01） ; the soil organic content decreased with increasing soil bulk density and increased with aggregate stability. This suggested that the soil organic carbon storage capacity was affected by the soil physical properties, which in turn could be changed by vegetation root activities.