全球植被碳储量的时空格局动态

Spatiotemporal Trends in Global Vegetation Carbon Storage

植被碳储量对生态系统碳平衡具有重要调节作用,对植被碳储量进行模拟并分析其对气候变化的响应是全球陆地生态系统碳循环和气候变化研究的重要内容。基于全球植被动态模型模拟的全球植被碳储量,分析植被碳储量在1901年-2000年间的时空变化趋势,及其与气温和降水的时空关系。将LPJ-DGVM(Lund-Potsdam-Jena Dynamic Global Vegetation Model)模型对植被碳储量的模拟结果与国际上被广泛接受的其他研究结果进行了对比后得出,该模型对植被碳储量具有较好的模拟能力。对植被碳储量的模拟结果表明:全球过去100年的植被碳储量在整体上呈增加趋势,增加率为0.0016kgC/(m2a),通过分段线性回归方法得出植被碳储量时间变化趋势存在显著的转折点,20世纪50年代初以前,植被碳储量具有下降趋势,线性斜率为-0.0014kgC/(m2a),之后植被碳储量呈现显著的增加趋势,增加率为0.0055kgC/(m2a),是整体增加率的3倍多,因此整体增加率显著低估了近半个世纪以来植被碳储量的实际增加率。在空间栅格尺度上的分析表明,植被碳储量对气候变化的响应具有很大的区域差异,在不同地区,温度和降水的变化对植被碳储量的变化趋势贡献不同,并与各地区植物生长所受的环境条件约束的状况有关。研究结论进一步说明LPJ能够较好的模拟植物生长与气候之间的相关关系、揭示植被碳储量变化规律和特征,另外为了更好地研究气候变化对植被碳储量的影响,下一步需要对LPJ进行改进,增强其对人类活动如土地利用变化和农业灌溉行为等的模拟能力。

Vegetation carbon storage plays an important role in regulating the terrestrial carbon balance. Simulating vegetation carbon storage and evaluating the relationship between carbon storage and climate change are important to climate change research. In this study,the spatiotemporal variation of global vegetation carbon storage simulated by the Lund Potsdam Jena Dynamic Global Vegetation Model（LPJ-DGVM） and its linkage with changes in temperature and precipitation from 1901-2000 were analyzed. Monthly data on field of precipitation,temperature, cloud cover,and soil texture were used. Estimates of global vegetation carbon storage made with the LPJ model are similar to those made by other studies,although the LPJ-derived result is at the high end of the range. The model cannot be fully validated with available information because the model assumes that vegetation is unaffected by human activities,that the spatial resolution of the simulation unit and sample data varies considerably,and because of a lack of sample data at a global scale. Model results showed a globally statistically significant positive trend for carbon storage during the entire study period （0.0016kgC/（m2·a））;however,two distinct periods with the opposite pattern were found. Vegetation carbon storage first decreased from 1901 to 1953 （-0.0014kgC（/ m2 ·a））,and then significantly increased from 1953 to 2000（0.0055kgC（/m2·a））. Further spatial analyses show that the linkage between vegetation carbon storage and temperature and precipitation differ greatly from one region to another. Our results demonstrate that the LPJ model can simulate the relationship between plant growth and climatic factors,however,the LPJ model can be improved by introducing data on land use change and irrigation.