蒙古高原植被变化趋势及其影响因素

Vegetation Changing Trend and Its Affecting Factors in Mongolian Plateau

基于1982—2006年的AVHRR数据和气象数据,分析了蒙古高原植被时空变化特征及其影响因素。研究发现:(1)近25a来,蒙古高原植被整体呈改善趋势,年增长率为0.000 6/a。蒙古国植被NDVI年增长率最大(0.000 8/a),其次是中国的内蒙古(0.000 4/a)、甘肃(0.000 3/a)和宁夏(0.000 1/a);(2)植被的变化趋势具有明显的空间差异性和季节性。25a来,蒙古国西北部、内蒙古中部的锡林郭勒盟等区域植被明显改善,而内蒙古东北部呼伦贝尔市植被呈退化趋势。研究区春、秋季植被明显改善,夏季植被呈退化趋势;(3)植被的变化趋势一定程度上受温度和降雨的影响,春、秋季升高的温度使生长期延长,植被改善,而夏季温度升高和降水减少共同导致夏季植被退化;(4)草地、农作物面积和产量的增加直接或间接地导致了内蒙古植被NDVI的增加,其他人为因素,如人口增长、土地利用类型的转换、退耕还林、过度放牧、矿产资源开采等也可直接或间接地影响植被的变化。

Based on the AVHRR NDVI data and climate data from 1982 to 2006in the Mongolian Plateau,the temporal and spatial variability of vegetation and its affecting factors were analyzed.The results showed that：（1）The vegetation of Mongolian Plateau had improved as a whole during the recent 25 years with the0.0006 per year increase rate of annual NDVI.Mongolia had the largest annual increase rate（0.000 8per year）,followed by Inner Mongolia（0.000 4per year）,Ningxia（0.000 3per year）and Gansu（0.000 1per year）Province of China.（2）The trend of vegetation had obvious differences in spatial and seasonal characteristics.The vegetation in Northwest Mongolia and the Xilinguole of Inter Mongolia had significantly improved in recent 25 years,while the Hulunbeir of Inner Mongolia showed degrading trend.The vegetation had significantly improved in spring and autumn,while degraded in summer.（3）The change trend of vegetation was affected by temperature and precipitation to some extent.Rising temperature extended the length of growing season,which promoted the vegetation growth in spring and autumn.Rising temperature together with reducing precipitation resulted in vegetation degradation in summer.（4）The increased area and yields of grassland and cropland,directly or indirectly,led to NDVI increased,and the other human activities,for example,increased population,changed land cover/land use,returning farmland to forest,overgrazing,exploitation of mineral resources,may also have impacts on the vegetation changes.