黑河中游荒漠绿洲区免灌植被土壤水分状况

Status of Soil Moisture in Oasis and Desert Unirrigated Vegetation Region along Middle Reaches of Heihe River Basin

对1年、3年、5年、20年梭梭人工林,20年的花棒、柽柳、柠条人工林及天然荒漠植被等立地土壤湿度研究表明:土壤湿度随植物盖度增大而减少,盖度>40%与盖度<5%的固沙植物花棒、柽柳和梭梭林地,土壤湿度分别相差0.72%,1.16%和1.28%;植物种间土壤湿度也有差异,相同密度下花棒土壤湿度>梭梭土壤湿度>柽柳土壤湿度。随着植物生长,土壤湿度下降。1年、3年和5年生梭梭人工林土壤储水量比未营造梭梭林的沙地分别降低23.00%,48.00%和58.00%。随着不同部位间水平距离的增大,土壤湿度变异较大;在垂直剖面上,随土壤深度增加,土壤湿度逐渐降低,梭梭、柽柳、花棒、柠条林地土壤湿度由(2.57±0.20)%,(2.04±0.17)%,(2.75±0.15)%和(2.20±0.07)%,下降至(1.19±0.25)%,(1.01±0.20)%,(1.31±0.18)%和(0.99±0.14)%。4月与9月荒漠植被泡泡刺沙堆、戈壁土壤湿度的差值分别为1.03%和0.81%。戈壁土壤水分垂直变化较大,20cm与160cm土壤湿度分别为(3.35±0.38)%,(1.39±0.04)%,相差3.08%。

Eight plots with vegetation form, growth age, coverage and position at the sand dune in oasis, one plot at shifting sand dune and two plot with the Nitraria sophaerocarpa Maxim. dune and the Gobi were chosen to monitor soil moisture with data investigated to determine impacts of the soil moisture regime on the middle Heihe river watershed. The results show : The soil moisture content (SM) decreases with the increase of vegetation coverage, and SM differences of Hedsarium scopar, Tamarix ramosissima and Haloxylon ammodendron forest, whose coverage are more than 40% or less than 5%,are 0.72%,1.16% and 1.28%, respectively. The SM in same coverage is Hedsarium scopar forest >Haloxylon ammodendron forest>Tamarix ramosissima forest. The soil water storage in Haloxylon ammodendron forest, which developed for 1 year,3 years and 5 years are lower of 23.00%,48.00% and 58.00%. At the level transect, the longer the distance between the plot is, the more obvious the change of SM is. At the vertical distribution, SM decreases with soil depth increasing. SM descends to(1.19±0.25)%,(1.01±0.20)%,(1.31±0.18)% and (0.99±0.14)% from (2.57±0.20)%,(2.04±0.17)%,(2.75±0.15)% and (2.20±0.07)% in Haloxylon ammodendron forest, Tamarix ramosissima forest, Hedsarium scopar forest and Caragana korshinskii Kom.forest,respectively. The differences of soil moisture of the Nitraria sophaerocarpa Maxim.dune and the Gobi in April and September are 1.03% and 0.81%,respectively. The SM vertical distribution changed sharply in Gobi. The SM at 20 cm and 160 cm layers are (3.35±0.38)% and (1.39±0.04)%,respectly,and the difference is 3.08%.