蒙古高原草原火行为的时空格局与影响因子

采用GIS空间分析方法和L3JRC遥感卫星数据,研究了2000—2007年间蒙古高原草原火行为的时空分布规律,比较了中国内蒙古自治区和蒙古人民共和国草原火行为的差异,分析了植被、气候与人文因素等对草原火行为的影响.结果表明:不同植被类型间的过火率存在极显著差异(P0.001),为草甸草原典型草原荒漠草原,蒙古人民共和国草原过火率显著高于中国内蒙古自治区(P0.001),过火频次的分布格局与过火迹地相一致.草原火行为存在明显的年际变化特征,草甸草原(r2=-0.54,P0.05)和典型草原(r2=-0.61,P0.05)的年过火率与年降雨量呈负相关关系;草原火集中在降水较少、风速较大的春、秋两季.中国内蒙古自治区的人口密度和载畜密度远高于蒙古人民共和国,而过火率则相反,表明人文因素,尤其是过度放牧是导致中国内蒙古自治区和蒙古人民共和国火行为差异的主要原因.

Spatiotemporal patterns and driving factors of grassland fire on Mongolian Plateau

By using GIS spatial analysis method and L3JRC remote sensing data, the spatiotemporal patterns of grassland fire on the Mongolian Plateau in 2000-2007 were examined, and the difference in the grassland fire activities between Inner Mongolia and Mongolia was compared. The effects of vegetation, climate, and human disturbance on the grassland fire were also analyzed. There existed significant difference (P<0.001) in the burned area ratio among three vegetation types, and decreased in the order of meadow steppe > typical steppe > desert steppe. The grasslands in Mongolia had significantly higher burned area ratio than those in Inner Mongolia (P<0.001), and the fire frequency had the same pattern with the burned area ratio. The fire activity differed significantly among years. The burned area ratio was negatively correlated with the annual precipitation in meadow steppe (r²=-0.54, P<0.05) and typical steppe (r²=-0.61, P<0.05). Fire activity also showed monthly variation, occurring mostly in spring and autumn when the weather was dry and windy. It was found that Inner Mongolia had much higher human population and livestock density but lower burned area ratio than Mongolia, suggesting that human disturbance, overgrazing in particular, was the major factor inducing the different patterns of grassland fire between Inner Mongolia and Mongolia.