重庆缙云山典型林分土壤有机碳密度特征

Soil organic carbon density of 4 forest types in Jinyun mountain of Chongqing

在全球气候变暖背景下,土壤有机碳库已经成为全球碳循环研究的重点之一。文章对缙云山针阔混交林、常绿阔叶林、毛竹林和灌木林土壤有机碳和C/N的特征进行了初步探索。结果表明,4种林分土壤有机碳含量和密度不同,且都随土壤深度增加有减少的趋势;其土壤有机碳密度的大小顺序为:灌木林(22.40kg·m-2)>针阔混交林(12.02kg·m-2)>毛竹林(10.09kg·m-2)>常绿阔叶林(7.97kg·m-2)。常绿阔叶林、针阔混交林和灌木林土壤有机碳主要存储于土壤Ⅰ层,其单位面积有机碳储量分别占总有机碳储量的82.18%、75.37%和68.17%;毛竹林土壤有机碳主要存储于土壤Ⅰ、Ⅱ层,这两层土壤单位面积有机碳储量占总有机碳储量的79.29%。4种典型林分的土壤C/N比也随土壤深度的增加呈现减少的趋势,与这4种林分土壤有机碳的剖面变化吻合,C/N平均值大小顺序为:灌木林(20.08)>毛竹林(9.18)>针阔混交林(8.85)>常绿阔叶林(3.00)。

Under urgent problems of global warming, soil organic carbon （SOC） pool has become one of the most important issues in study of global carbon cycle. In this research work both the SOC and total N content in the soil samples, collecting from four forest types （mixed forest, evergreen broad-leaved forest, bamboo forest, shrub forest） in Jinyun Mountain of Chongqing, were determined. Furthermore, the characteristics of SOC and C/N were analyzed, respectively, and the results showed that the different content of SOC and its density under these four forest types decreased with the soil depth. The quantity order of SOC density associated with the soil under these four forest types was shrub forest （22.40 kg.m^-2）〉mixed forest （12.02 kg.m^-2）〉bamboo forest （10.09 kg.m^-2） 〉evergreen broad-leaved forest （7.97 kg.m^-2）. The SOC of evergreen broad-leaved forest, mixed forest, shrub forest mainly stored in Ⅰ horizon and their SOC stock per unit area in this horizon were 82.18%, 75.37%, 68.17% of total SOC stock in each forest type, respectively. In bamboo forest, both Ⅰ and Ⅱ horizons were the main places for SOC storage, and 79.29% of SOC stock per unit area was found at there. As same as the profile variation of SOC, the C/N ratio also showed a decreasing trend with soil depth. The average values of C/N ratio in soils under these four forest types were： shrub forest （20.08）〉bamboo forest （9.18）〉mixed forest （8.85） 〉evergreen broad-leaved forest （3.00）.