黄土丘陵区典型人工林有机碳分布特征及其影响因素

分析了黄土丘陵区典型人工林刺槐、沙棘和柠条0-60 cm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--40 cm土层,年平均补给量为0.357g/kg；刺槐和柠条为40-60 cm,年平均补给量分别为；0.010和0.005 g/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.

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

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 ofsoil organic content in the 0-60cm soil layers of typical plantations of Robinia pseudoacacia,Hippophaerhamnoides,Caragana intermediain the loess hilly region.The results showed that the plantations playedpositive roles in soil organic carbon accumulation.After reaching their stable growth stages,the plantationsshowed replenishment effects on the soil organic carbon pool.The replenishment ability of the plantationscould be ranked in a decending order as Hippophae rhamnoides>Robinia pseudoacada>Caragana intermedia,with average annual replenishment rates of 0.854,0.004and 0.003g,respectively.Owing to thedifferences 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 20-40cmlayer with an annual replenishment rate of 0.357g,while for Robinia pseudoacada and Caragana intermedia,the increases were found at the layers of 40-60cm with rates of 0.010and 0.005g/kg,respectively.Moreover,the results also indicated significant correlation between soil physical properties and soil organiccontent(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.