黑河中游荒漠绿洲过渡带土壤水分与植被空间变异

Spatial variability of soil moisture and vegetation in desert-oasis ecotone in the middle reaches of Heihe River Basin

荒漠绿洲过渡带是绿洲生态系统的重要组成部分,对维持绿洲稳定具有重要作用。过渡带土壤湿度和植被之间的相互关系是了解荒漠绿洲过渡带的重要科学问题,从而开始受到重视。研究是在黑河中游荒漠绿洲过渡带,选择一条1700m×200m的样带(包括3条平行样线),在对土壤湿度、植被高度、盖度等调查的基础上,应用统计分析和地统计的方法,研究了荒漠绿洲过渡带土壤水分和植被的空间变异性特征。结果表明:在荒漠绿洲过渡带上,0～200cm土层中土壤平均湿度介于1.45%～3·85%,变异系数在27.7%～83.2%;植被盖度介于9%～80%,变异系数为80%。植被盖度、冠幅与0～20、20～40cm两层土壤湿度显著负相关(p<0.05),与120～140、140～160cm两层土壤湿度显著正相关(p<0.01)。土壤水分和植被空间分布在样带上存在明显的空间异质性,表现在小于100m的尺度上随机分布,而在100～3110m的尺度上呈聚集分布格局。

Desert-oasis ecotone, an important constituent of oasis ecosystem has vital role in maintaining the stability of oasis. The correlation between soil moisture and vegetation of the ecotone is the primary scientific issue to better understand the desert-oasis ecotone. This study, a transaction of 1700m × 200m with three parallel sampling lines was established and soil moisture, vegetation height and coverage were investigated. The characteristics of spatial heterogeneity in soil moisture and vegetation distribution and their relationships were identified using the method of classical statistic and geostatistical analysis. The result show： in the desert-oasis ecotone, the soil moisture at the 0 -200cm soil layer is, on average, 1.45% -3.85% and the variable coefficient is 27.7% - 83.2% ; the vegetation coverage is 9% - 80% and the variable coefficient is 80% . The coverage and crown diameter are negatively related （p 〈 0.05 ）to the soil moisture at the 0 -20cm and the 20 -40cm , and are positively related（p 〈0.01 ） to the soil moisture at the 120 - 140cm and 140 - 160cm. Soil moisture and vegetation exist strong distribution pattern of spatial heterogeneity, showing a random distribution at small scale （ 〈 100m） and a mass distribution structure in larger scale（ 100-3110m）.