科尔沁地区不同类型沙地土壤水分的时空异质性

应用半干旱区科尔沁沙地2006-2010年5-9月份土壤水分定点观测资料,研究农田、沙质草地和固定沙丘土壤水分的时空变异性。结果表明:2006年5月-2010年9月,(1)农田、沙质草地和固定沙丘土壤水分都在7月份最高;农田7月份土壤水分与5、6月份的差异显著,沙质草地7月份的与8、9月份的差异显著,而固定沙丘7月份的与生长季其他月份的都有显著差异;(2)3个样地土壤水分随年份有逐渐增加的趋势;(3)农田、沙质草地和固定沙丘0-160cm平均土壤含水量分别为20.69%,7.63%,3.61%,农田土壤水分明显高于沙质草地和固定沙丘,而且3种样地间土壤水分差异显著;(4)3个样地土壤水分随土层厚度增加呈"先增加后减少,最后又增加"的趋势;农田0-20cm土壤水分与20-40cm,40-60cm,120-140cm及140-160cm的差异显著;沙质草地0-20cm土壤水分除与140-160cm有显著差异外,与其他土层均无显著差异;固定沙丘土壤水分只有100-120cm与140-160cm的差异显著;(5)研究区降雨的季节分配极不均匀,主要集中在4-10月的生长季,占全年降雨量的92.58%;0～5mm降雨占全年降雨事件的73.29%,但其降雨量只占全年降雨量的25.1%;降雨间隔期以0～10d为主,占全年无降雨期的37.6%;0～10d降雨间隔期出现的频数最高,占全年间隔期频数的86.9%;(6)当土壤水分较高时,其变异性会随着土壤水分的增加而减小,而当土壤水分较低时,其变异性随土壤水分的增加而增加。

Spatio-temporal Variability of Soil Moisture in Different Dunes of Horqin Sandy Land

Based on the observed data of soil moisture in growing season from 2006 to 2010,the spatio-temporal variability of soil water moisture in farmland,sandy grassland and fixed sand dune in Horqin sandy land was analized.From 2006 to 2010,the results showed that:(1)Soil moisture of the three sites was getting the highest in July;for farmland,the soil moisture in July was significantly different from that in May and June,and that of the sandy grassland in July was significantly different from that in August and September,at fixed sand dunes,its soil moisture in July was significantly different from that in other months of growing season;(2)Soil moisture showed a gradually increasing trend;(3)The average of soil moisture in farmland,sandy grassland and fixed sand dune were 20.69%,7.63% and 3.61%,respectively;(4)The general trend of soil moisture with increasing soil depth was firstly increased,and then decreased,and finally increased again.Soil moisture of farmland at 0-20 cm was significantly different from that at 20-40 cm,40-60 cm,120-140 cm and 140-160 cm;for the sandy grassland,soil moisture was significantly different from that at 0-20 cm and 140-160 cm;for the fixed sand dune,the soil moisture was significantly different from that at 100-120 cm and 140-160 cm;(5)The seasonal distribution of precipitation in study area was very uneven,the rainfall in April to October accounted for 92.58%;0～5 mm rainfall events accounted for 73.29%,but its rainfall only occupied 25.1%;the interval of rainfall in 0～10 d accounting for 37.6% of period without rainfall;and 0～10 d interval had the highest frequency,which accounted for 86.9%;(6)When soil moisture was higher,the variation was decreased with increasing moisture,and when soil moisture was lower,the variation was increased with moisture increase.