塔里木河冲积平原胡杨林的土壤水分状况研究

 通过英巴扎断面实测资料，对塔里木河冲积平原胡杨(Populus euphratica)林的土壤水分状况进行了研究。结果表明：在胡杨幼林区域，地下水埋深1～2m，水质为1～3g·L-1的微咸水，且此区域可被洪水漫溢，整个土壤剖面土壤含水率都很高，利于胡杨种子萌发与植株扎根。在胡杨青壮林区域，地下水埋深2.5～4m，但地下水水质仍为1～3g·L-1。由于多数年份不能被洪水漫溢，土壤表层水分含量低，此区域难以满足胡杨幼林对水分的需求。但是，对于胡杨青壮林来说，它能够吸收2.5～4m深的土壤水分，因而此区域可以满足它的生长要求。在胡杨衰败林区域，地下水埋深已达5～10m，不能满足胡杨生长的要求，使得胡杨在逐步枯萎和衰败。

SOIL WATER REGIME IN POPULUS EUPHRATICA FOREST ON THE TARIM RIVER ALLUVIAL PLAIN

The soil water regime in Populus euphratica forest was studied in the alluvial plain of Tarim River, Yingbaza section. Patterns varied according to the age of the forest stand: in young forest zones groundwater was 1-2 m deep and lightly salt (1-3 g*L-1). The zone is often flooded during typical high water stages and has a high content of soil water, it is suitable for the growth of Popular euphratica seedlings. In the mature forest zone, groundwater is 2.5-4 m deep but still slightly salt (1-3 g*L-1). As the zone is flooded only in especially wet years and the soil water content in the surface layer is low, the water condition significantly limits the growth of Populus euphratica seedlings. The depth of groundwater observed in these forests is in the reach of the roots of mature trees and the conditions are suitable for mature forest growth. In the degraded forest zone, groundwater depth was 5-10 m, exceeding the critical depth for typical growth of Populus euphratica and soil moisture supply is in seriously deficit, causing Populus euphratica stands to degrade and wither.