黄土丘陵沟壑区不同植被类型土壤有效水和持水能力

以黄土丘陵沟壑区坊塌流域不同植被类型为研究对象,在野外调查的基础上,利用离心机法测定不同植被类型0—10、10—20 cm土层不同吸力下的土壤含水率,并利用Van Gennuchten模型对土壤水分特征曲线进行拟合,对比分析了不同植被类型不同土层土壤水分特征曲线、土壤水分有效性和持水性。结果表明:随着植被恢复的进行,不同植被类型土壤水分特征曲线出现了明显的差异,但是其斜率基本不变且不同植被类型0—10、10—20 cm土层土壤水分特征曲线都呈近似的"S"型;不同植被类型0—10、10—20 cm土层土壤有效水范围分别为22.65%—26.80%、23.97%—28.13%,除白羊草群落和刺槐林外呈现出多年生蒿禾类群落低于灌木群落而高于一年生草本群落的变化趋势;不同植被类型土壤持水能力在0—10 cm土层没有显著性差异,在10—20 cm呈现出多年生蒿禾类群落低于灌木群落而高于一年生草本群落,其中白羊草群落最大,刺槐林最低。刺槐林有效水分和土壤持水能力都较低,建议适当采取间伐并促进其近自然化恢复来实现土壤水分的可持续利用,尽量避免在阳坡缺水地区种植刺槐。对于研究地区土壤水分的可持续利用、植被恢复和科学合理的进行植被配置具有重要意义。

Soil water availability and holding capacity of different vegetation types in hilly-gullied region of the Loess Plateau

Based on field investigations, the soil moisture of different suction in 0-10cm Soil layer and 10-20cm Soil layer from different vegetation types in Fangta watershed in hilly-gullied region of the Loess Plateau, was measured using a high-speed centrifuge, and the water characteristic curves were obtained using the mathematical models of Van Gennuchten. Then, parameters such as soil moisture characteristic curves, soil water capacity, and soil moisture availability in the 0-10 cm and 10-20 cm soil layers were compared among different vegetation types. The results showed that the soil water retention curves were obviously different in both profiles of different vegetation types, but all soil water retention curves among different vegetation types appeared as approximate "S" shapes. The range of soil available water in the 0-10 cm and 10-20 cm soil layers were 22.65%-26.80% and 23.97%-28.13%, respectively, among different vegetation types, where soil moisture availability of grass communities and the perennial Artemisia communities was greater than that of the annual herbaceous community and less than that of shrub community except the Bothriochloa ischaemum community and the Robinia pseudoacacia forest. There were no significant differences in the 0-10 cm soil layer among different vegetation types, but in the 10-20 cm soil layer, soil water capacities of grass communities and the perennial Artemisia communities were higher than that of the annual herbaceous community and lower than that of the shrub community. Its maximum was in the Bothriochloa ischaemum community and the minimum was in the Robinia pseudoacacia forest. As soil available water and soil water capacity of Robinia pseudoacacia were at relatively low levels, intermediate cuttings can be taken to promote natural recovery and eventually realize the sustainable utilization of water inartificial Robinia pseudoacacia forests. This provides a good opportunity to Robinia pseudoacaciaon some slope conditions such as shady slopes and gaps, where soil water conditions are more favorable. This research was significantly important for sustainable utilization of water, vegetation restoration, and vegetation configuration in the study area.