The relation of surface environmental transition to variation of dry and wet climate in Horqin sandy land, China

摘要

This paper relates the variation of dry and we I climate to regional environmental change in Horqin sandy land of China. Desertification in Tong-Liao city has stretched to an area of 32,370km~2, which accounts for 53.8 percent of the total land areaof the whole city. Seriously descrtified, rapidly developing and developing areas in the whole desertification zone are 1,170 km~2 (2 percent). 3,810 km~2 (6.3 percent) and 16,590 km~2 (27.6 percent) respectively. The variation in spatial and temporal desertification is linked with variations in precipitation. For more than one hundred years, all Ihe variables of environmental problems which include desertification, sandstorm and degeneration of grassland in Horqin area have been consistent with variations in precipitation. At present the effect of human aclivitv on some local area has surpassed natural factor and may become the major or initiating factor. Although, in general, it is seen that the trend in environmental transition closely correlates with that of nature and. in particular, is completely in keeping with the trend in climatic variation, it is proved that human activity can accelerate and extend the scope of environmental variation. The exponent of annual tree rings and number of sandstorm showed no difference in their variation characteristics of cycle period with hydro-meteorological elements such as precipitation. For dry stage, the number of strong sandstorm increases, while the exponent of annual tree rings decreases, the variationis incompatible for wet stage.