摘要
本文应用1982～1993年间每10天间隔的卫星数据资料研究了在过度放牧压力下中国半干旱地区草地的生物生产力状况。通过计算每年植被峰值得出了64km^2象元的线性趋势,该植被峰值通过取每年8月和9月的6个归一化植被指教(NDVI)的平均值而获得,并用地理信息系统(GIS)显示出生物量的空间和相对变化。用NDVI表示的生物生产量在这12年期间总体上是增长的,同时还研究了NDVI动态变化与降雨量之间的相关关系。研究发现,黄河两岸灌溉农田大量增加,这就证实了向集约化耕作方向发展以及农田防护林建设使生物量增加的趋势。草地的生物生产量有少量的增长,但与降雨量并没有对应关系。另外,还讨论了在这一地区实施的各种沙漠化防治措施,这些措施的实施大概正好解释了生物量的正增长变化。
Ten-day intervals of satellite data between 1982 and 1993 are used to investigate the status of biological productivity on a rangeland in semiarid China exposed to high grazing pressure. Linear trends for 64 km2 pixels are calculated through annual vegetation peak values, constructed by averaging the 6 Normalized Difference Vegetation Index (NDVI) values for August and September each year, and displayed in a GIS exposing the spatial and relative changes of biomass. Biological production, expressed as NDVI, has increased in general over the 12-year period and the correlation between precipitation and NDVI dynamic is tested. High increases are found for irrigated farmland along the Yellow River confirming a trend toward intensified cultivation and increased biomass from planted trees for farmland protection. Production on the rangeland has increased slightly without correspondence in rainfall. Instead, different measures implemented in the area to combat desertification are discussed as being likely explanations for the positive change.
