民勤绿洲区天然胡杨林生长季土壤水分动态

Soil Moisture Dynamics During Growing Season of Populus Euphratica Forest in Minqin Oasis

利用地统计学方法对民勤绿洲区天然胡杨林下土壤水分的空间结构特征及生长季期间的变化规律进行了研究。结果表明,研究区天然胡杨林下土壤水分含量范围为0.85%～4.80%。民勤县双茨科乡和苏武乡天然胡杨林下土壤含水量随土层深度的增加呈增大趋势,而夹河乡样区土壤水分含量随土层深度的增加呈现出先增大后减小的趋势。8月份各采样点表层土壤含水量均为最小值。土壤水分含量在胡杨的生长季期间总体表现为:春季>秋季>夏季。采样点土壤水分变异系数总体属于中强度变异性,表层土壤水分的变异系数略大。胸径大的胡杨树土壤含水量反而少,这主要与树龄及胡杨林根系发达程度有关。土壤水分异质性为中等程度的空间相关性,且苏武乡变异函数模型拟合效果最为理想。

The temporal variability of soil water and its dynamics in Populus euphratica growth period in Minqin Oasis was investigated using geostatistics. The results show that the soil water content ranged be- tween 0. 85% ~ 4. 80% in the study area. The soil water contents increased with soil depth in both Shuangcike and Suwu Towns, while increased first and then decreased with the depth in Jiahe Town. The surface soil water content reached the lowest value in August. The soil water content in the growing season of the natural Populus euphratica forests varied considerably; the soil water content was higher in the spring, intermediate in autumn, and lower in summer. The variation efficient in general indicated a middle or strong variability in soil water content. However, the variation efficient of surface soil water content was greater than the others. The soil water content was less under Populus euphratica trees with greater diame- ters, which mainly related to the tree-age and root system. Overall, the soil water contents exhibited inter- mediate spatial correlation, and the variograms model for Suwu Town had the highest fitting coefficient.