呼伦贝尔叶面积指数变化及其对气候的响应

Changes of Leaf Area Index and Its Response to Climate in Hulun Buir

利用MCD15的叶面积指数(LAI)数据集,采用趋势线法、变异系数法和相关系数法,对2003-2019年呼伦贝尔市的LAI时空分布变化及其对气候的响应进行分析。分析结果表明:呼伦贝尔市的平均年最大LAI为3.5,总体呈现森林的LAI>耕地的>草原的分布。最大LAI的平均变化速率为0.03/a,生态环境持续改善,但在大兴安岭西侧草甸草原区、莫力达瓦达斡尔族自治旗等地受草地退化、毁林开荒等因素影响,存在LAI变化速率小于0的区域。呼伦贝尔市的平均年最大LAI的平均变异系数为0.18,大兴安岭及两麓地区生态环境较为稳定,而草原区生态环境相对脆弱。呼伦贝尔森林的年最大LAI与年平均气温呈极显著正相关,而草原和耕地与年降水量呈极显著正相关。每年生长季初期,呼伦贝尔市的LAI主要受气温影响。6月份开始,森林LAI受气候的影响不再明显,而耕地和农田的LAI则主要受降水影响。

Using the MCD15 leaf area index(LAI)dataset as well as the trend line method,coefficient of variation method and correlation coefficient method,the spatio-temporal distribution of LAI and its response to climate in Hulun Buir of Inner Mongolia during 2003—2019 are analyzed.The results show that the average annual maximum LAI in Hulun Buir is 3.5,showing the distribution of forest LAI>cultivated land LAI>grassland LAI.The average change rate of the annual maximum LAI is 0.3 per decade,thus the ecological environment has been improving constantly.However,affected by grassland degradation,deforestation and land reclamation,there are areas with the LAI change rate below 0 in the meadow grassland area on the west side of the Greater Khingan Mountains and the Morin Dawa Daur Autonomous Banner.The average coefficient of variation of the average annual maximum LAI in Hulun Buir is 0.18.The ecological environment of in the Greater Khingan Mountains and the two foothills is relatively stable,while the ecological environment of grassland area is more fragile relatively.The correlation between annual maximum LAI and annual mean temperature is positive in the forest of Hulun Buir,so is the correlation between the grassland and cultivated land and the annual precipitation.The LAI of Hulun Buir is mainly affected by temperature at the beginning of each growing season.Starting from June,the impact of climate on forest LAI is no longer evident,but the LAI of cultivated land and farmland is mainly influenced by precipitation.