摘要
为探究造林后表层(0~20 cm)土壤有机碳变化的影响因素,收集并筛选出全球390组造林后表层土壤有机碳变化的文献数据,利用逐步线性回归和随机森林模型分析造林后土壤有机碳指标变化及土壤、气候和土地利用因素对土壤固碳的影响,在此基础上采用随机森林模型估算中国8个气候区退耕还林情景下表层土壤有机碳指标变化。结果表明:1)造林后土壤有机碳密度占生态系统有机碳密度比例主要受土壤初始有机碳密度和乔木地上、地下有机碳密度影响,土壤有机碳密度变化量主要受土壤质地和土壤初始有机碳密度影响。树种根冠比越大、土壤黏粒与粉粒含量越高、土壤初始有机碳密度越低,越有利于表层土壤有机碳累积。2)我国不同气候区退耕还林40年后表层土壤有机碳密度平均增加2.68~12.88 Mg C hm^(-2),土壤有机碳密度占生态系统有机碳密度比例从造林5年后的61.21%~92.87%降至造林40年后的25.67%~61.09%,暖湿气候条件比冷干气候条件的下降速率更大,表明冷干气候区土壤固碳速率与植被固碳速率相关性更高。
In order to explore the factors which influence topsoil(0~20 cm)organic carbon change after afforestation,390 groups of study data on topsoil organic carbon after afforestation were selected by literature research,and the changes of soil organic carbon(SOC)indicators after afforestation and the effects of soil,climate and land use factors on SOC sequestration were analyzed based on the stepwise linear regression model and the random forest model.And the random forest model was used to estimate the changes of SOC indicators under different afforestation scenarios in eight climatic regions of China.The results showed that the proportion of SOC density to ecosystem organic carbon density after afforestation was mainly affected by the initial surface SOC density,aboveground and underground biomass organic carbon density,and the change of SOC density was mainly affected by the soil texture and the initial surface SOC density.With tree growing,larger the root-shoot ratio would benefit the SOC accumulation more.The higher the clay+silt content was and the lower the initial surface SOC density was,the more benificial to SOC sequestration.The results of regional estimation showed that the surface SOC density increased by 2.68~12.88 Mg C hm^(-2) on average after 40 years under"Grain-for-Green"Program in different climatic regions of China.The proportion of SOC density to ecosystem organic carbon density decreased from 61.21%~92.87%in 5 years after afforestation to 25.67%~61.09%in 40 years after afforestation.The decrease rate was greater in warm and humid climate than in cold and dry climate,showed that there was a higher correlation between SOC sequestration rate and vegetation organic carbon sequestration rate in the cold and dry climate region.
作者
王艺杰
于丽君
张稳
孙文娟
WANG Yi-jie;YU Li-jun;ZHANG Wen;SUN Wen-juan(State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chinese Academy of Sciences,Beijing 100093;University of Chinese Academy of Sciences,Beijing 100049;State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry,Institute of Atmospheric Physics,Chinese Academy of Science,Beijing 100029,China)
出处
《地理与地理信息科学》
CSCD
北大核心
2022年第2期103-111,共9页
Geography and Geo-Information Science
基金
国家自然科学基金项目(41871038)。
关键词
造林
森林有机碳密度
土壤有机碳密度
土地利用变化
afforestation
forest biomass organic carbon density
soil organic carbon density
land use change
