滇黔桂地区土壤有机碳储量与影响因素研究

土壤有机碳(SOC)库在陆地生态系统中具有重要作用.由于土壤剖面数量和采用的土壤图比例尺等的限制,目前土壤有机碳库估箅尚存在很大不确定性.为了提高SOC库估算的精确性,利用798个土壤剖面及1:50万土壤图估算了滇黔桂地区(云南省、贵州省和广西壮族自治区)的SOC储量,并采用逐步回归分析和通径分析方法分析了影响SOC密度的主要因子.结果表明,滇黔桂地区表土层(0-20 cm)和土壤剖面(0-100 cm)的SOC储量分别为4.39 Pg和10.91 Pg;SOC密度分别为56.2Mg·hm-2和139.8 Mg·hm-2.高于全国平均水平.环境因子(海拔、经度、纬度、气温和降雨)、成土母质和土地利用方式对表土层和土壤剖面SOC密度变异性的解释度分别为37.9%和30.7%;环境因子为影响SOC密度的主要因子.环境因子中.气温对SOC密度的影响大干降雨,其中气温和降雨的变化分别主要由海拔和纬度的变化引起的.除气温和降雨外,还有其它随海拔或经纬度而变化的因子也对SOC密度产生显著影响,这种影响要大于降雨的影响.

Estimates and Affecting Factors of Soil Organic Carbon Storages in Yunnan-Guizhou-Guangxi Region of China

Soil organic carbon (SOC) plays a key role in the terrestrial eco-systems. However, there is a large variation in SOC estimates at regional and global scales. In order to improve the accuracy of SOC estimates, the SOC storage in Yunnan-Guizhou-Guangxi Region of China (include Yunnan Province, Guizhou Province and Guangxi Zhuang Municipality) was estimated using 798 soil profiles and 1:500 000 digitized soil map, and the dominant affecting factors on SOC density were also discussed employing stepwise regression and path analysis. Results showed that the SOC storages estimated in the 0-20 cm and 0-100 cm layers are 4.39 Pg and 10.91 Pg, respectively; and the corresponding SOC density are 56.2 Mg x hm(-2) and 139.8 Mg x hm(-2), respectively. The mean SOC density of Yunnan-Guizhou-Guangxi Region is higher than that of China. The environmental factors (including altitude, longitude, latitude, annual mean precipitation and annual mean temperature), soil parent materials and land use could explain 37.9% and 30.7% of the variability of SOC density to the upper 20 cm and 100 cm, respectively. The environmental factors are the dominant affecting factors of SOC density. The effect of temperature is more important than that of precipitation, and the temperature and precipitation mainly vary with altitude and latitude, respectively. Except for temperature and precipitation, there are also other factors varying with altitude, longitude and latitude significantly affect SOC density. And the effects of other factors are more important than that of precipitation.