粤东北山区几种森林土壤有机碳储量及其垂直分配特征

研究了粤东北山区的天然常绿阔叶林、针阔混交林、马尾松针叶林和桉树人工林等4种主要森林类型土壤有机碳储量及其分配特征.结果表明:(1)4种林分土壤有机碳平均含量在8.14～12.24 g/kg之间,常绿阔叶林最高,其次为针阔混交林.桉树人工林最小.土壤有机碳含量随深度增加而递减.但植被类型不同其减少程度不同.其中阔叶林变化幅度最大达72.04%.土壤有机碳表聚性明显.(2)4种林分土壤碳密度存在显著差异,其各土层变化范围为1.57～5.18 kg/m~2.土壤碳密度亦随深度增加而减少,自然地带性植被类型各个土层土壤碳密度均高于次生植被类型对应的碳密度.对于整个土层而言,各林分土壤碳密度在12.28～15.90 kg/m~2之间,总平均值为14.14 kg/m~2.(3)4种林分土壤碳储量整体较低,平均值为141.43 t/hm~2,表层土壤碳储量贡献不大.人为干扰活动对研究区森林土壤碳储量影响明显,是制约土壤碳储量大小的重要因素.

Study on the Soil Organic Carbon Storage and Vertical Distribution of Several Forest Types in Mountain Area of Northeast Guangdong

There are four main forest types in Northeast Guangdong, and the forest types are natural evergreen broad-leaved forest, pine and broad-leaved mixed forest, P. Massioniana forest and artificial eucalyptus forest. Using the method of field investigation, soil sampling and laboratory analysis, the storage and distribution of soil organic carbon for the four main forest types in Meijiang district have been discussed. The results were as follow; (1) The average soil organic carbon content for the four forest types was 8. 14～12. 24 g/kg, the soil organic carbon content in evergreen broad-leaved forest was highest but lowest in eucalypt forest. Soil organic carbon contents generally decreased with depth, but decrease range was different for the four forest types, and change range of broad-leaved forest is highest (72. 04%). The soil organic carbon assembled obviously in surface layer soils. (2) Soil carbon density in the four forest types change greatly, with a range of 1. 57～5.18 kg/m~2 for five soil depth intervals. Soil carbon density decreased generally with the depth, too. Soil carbon density under natural vegetation was significantly higher than that under secondary vegetation. For the whole soil section, soil carbon density in all forest types varied from 12. 28～15. 90 kg/m~2, and their total mean values were 14. 14 kg/m~2. (3) The total mean value of carbon storage was 141. 43 t/hm~2 in the four forest types. By comparisons, soil carbon storage of the main forest types in mountain area of Northeast Guangdong was lower than that of other regions, and the four main forest types had lower proportion of carbon contained in the upper soil layer. These results showed that human impact was one of factors that exert a tremendous influence on soil carbon storage.