沙坡头地区风沙土的水热状况

对多年监测资料的研究表明:流动风沙土稳定含水量为2%~3%,凋萎湿度为0.54%,相对有效水分多,对植物生长有利。天然植被下的固定风沙土,在35~40cm以下土层水量减少至1%~2%;人工植被下的固定风沙土水分条件更差,在3m深土层,除降雨后的短时间内,0~60cm土层含水量稍高外,无雨时段,3m深土层的含水量是1%~2%,甚至小于1%。这种水分状况导致多年生深根植物逐渐衰退,适应性一年生草本植物侵入。

WATER AND HEAT CONDITION OF BLOWN SAND SOIL IN SHAPOTOU REGION

Moisture is the key factor for the research and melioration of blown sand soil.The moisture of blown sand soil in the Shapotou region entirely comes from atmospheric precipitation.Shifting blown sand soil,with an unstable surface,is always in a conditon of deflation and accumulation.Its moisture content varies between 2%~3%,and withered coefficient amounts to 0.54%.Fixed blown sand soil tends to have an increasingly stable surface.Its black or brown crust with higher water capacity hinders water infiltration and replenishment into deep layer.Owing to plant evapotranspiration,its water condition is becoming worse,with a moisture content ranging from 1%~2% or less.Such a water change leads to the degradation of deep rooted plants and the invasion of annual plants as well as the succession of artificial ecosystem towards natural ecosystem.