内蒙古典型草原地上生物量的空间格局及其气候成因分析

内蒙古典型草原区的格点地上生物量与格点的纬度和经度均存在显著正相关关系,呈现北高南低、东高西低的空间分布格局;各气象站点所在地的草地地上生物量与多年平均年降水量之间存在显著正相关关系,与多年平均年均温之间存在显著负相关关系,而与多年平均年干燥度之间亦存在显著负相关关系,且在干燥度介于1~1.5的地区,地上生物量对干燥度变化的响应非常敏感;草地地上生物量的空间分布格局主要是在水热条件共同作用下形成的,年降水量的近东西向分布决定地上生物量分布的近东西向分异特点,而气温和降水的共同作用决定地上生物量分布的近南北向分异特点。

Spatial Patterns of Aboveground Biomass and Its Climatic Attributions in Typical Steppe of Inner Mongolia

Studying a high spatial-resolution distribution pattern of observed aboveground biomass of grasslands and its climatic attributions within a continuous geographical area and during a specific time period is crucial for assessing responses of the net primary production of grasslands to climate change, and validating satellite derived and model estimated grassland aboveground biomass. Using statistical data of the grassland investigation in Inner Mongolia during the 1980s and Geographic Information System techniques, we produced a distribution map of the grassland aboveground biomass with a 1km?1km spatial resolution for the typical steppe of Inner Mongolia, and then analyzed the spatial patterns of the aboveground biomass and its relation to thermal-moisture conditions. The grid aboveground biomass has a significantly positive correlation with latitudes and longitudes of the corresponding grids (P<0.001), representing a decreased tendency from north to south and from east to west. The aboveground biomass at meteorological stations has a significantly positive correlation with mean annual precipitation (P<0.001) and a significantly negative correlation with mean annual air temperature (P<0.001) and mean annual aridity index (P<0.001). It is worth to note that in areas with the mean annual aridity index between 1 and 1.5, the aboveground biomass has a very sensitive response to changes of the aridity index. The spatial patterns of the aboveground biomass was therefore shaped under the controls of thermal-moisture conditions: longitudinal distribution characteristics of the aboveground biomass were mainly determined by mean annual precipitation, whereas latitudinal distribution characteristics of the aboveground biomass were influenced by both mean annual air temperature and mean annual precipitation.