不同植被恢复模式对黄土高原丘陵沟壑区土壤水分生态效应的影响

研究了渭北黄土高原丘陵沟壑区内侧柏、荆条、20年刺槐、4年刺槐、4年苜蓿、农地不同植被恢复模式土壤水分生态效应,结果表明:不同的植被恢复模式土壤容重均低于对照农田,减小幅度为16%~8%,孔隙度增加,总孔隙度增幅为24.5%~8.1%,毛管孔隙度增幅为1.2%~13.9%,非毛管孔隙度增幅为20.5%~90.0%;土壤持水性比农地增加33%~7.5%;水分补给量在0~2m范围内,侧柏、荆条、4年刺槐是农地的2、1.5、1.71倍,20年刺槐和苜蓿比农地低22.5%和31.4%;0~1m内,侧柏、荆条、4年刺槐分别是农地的2.16、1.78、1.85倍,20年刺槐、苜蓿为农地的25%和62.3%;>0.25mm水稳性团聚体含量比农地增加56.84%~30.72%;土壤结构破坏率农地最高为41.09%,其它植被为6.67%~25.73%。相关性分析表明土壤容重、总孔隙度、水分特征曲线a、水稳性团聚体含量、结构破坏率相关性显著。不同植被土壤水分生态效应不同,除20年刺槐、苜蓿土壤水分补给量小于对照农地外,其它各项指标均显著优于农地。

Effect of Different Vegetation Recovery Modes on Soil Moisture Ecoeffects in Hilly and Gully Region of the Loess Plateau

Vegetation recovery is one of the major measures to improve eco-environment of the Loess Plateau. In order to find the ecological effects of different vegetation recovery modes on soil moisture in this region, six trial sites in Ranjiagou were studied. The results showed that compared to farmland, the soil bulk density under the recovery modes of Platycladus orientalis, Vitex negundo var. heterophylla, 20-year Robinia pseudoacacia, 4-year Robinia pseudoacacia and 4-year Medicago sativa L declined dramatically with a percentage of8%-16%; total porosity, capillary porosity and non-capillary porosity apparently increased by 24.5%-8.1%, 1.2%-13.9% and 20.5%-90.0%; the water retention capability of soil increased by 33%-7.5%; the water supply capacity under the mode of Platycladus orientalis, Vitex negundo var. heterophylla and 4-year Robinia pseudoacacia were 2.16, 1.78 and 1.85 times of the farmland while the 20-year Robinia pseudoacacia mode and 4-year Medicago sativa L mode were 25% and 62.3% of the farmland; >0.25mm water stable aggregates were increased by 56.84%-30.72% by all the recovery modes compared to the farmland; the structure fragmentation rate of soil under all recovery modes was 16.2%-62.6% while in farmland it was as high as 41.09%. The correlation analysis indicated there was a significant correlation of soil bulk density, total porosity, water characteristic curve, water stable aggregates and structure fragmentation rate, so the conclusion could be drawn as every vegetation recovery mode has a better ecological effect on soil water than farmland except for the water supply capacity of 20-year Robinia pseudoacacia and 4-year Medicago sativa L.