黄土丘陵半干旱区人工林迹地土壤水分恢复研究

    Soil water restoration of different land use after artificial forest in the semi-arid area of Loess Plateau

    • 摘要: 为了研究黄土丘陵半干旱区人工林迹地土壤水分恢复情况,该文以正在生长的人工林土壤水分含量为人工林迹地土壤水分恢复的起点,并分别以持续农地和持续放牧荒坡的土壤含水量为林后农地和草地土壤水分恢复的上限,对位于黄土丘陵半干旱区绥德县境内的人工林迹地土壤水分恢复情况进行了研究。结果表明,人工林死后的放牧荒坡在20a的时间里,其土壤水分没有补偿;人工林死后的保护草地土壤水分有微弱恢复迹象,但年恢复速度在0.5~3.7 mm之间,以这样的速度恢复到持续放牧荒坡的土壤含水量,至少需要150a以上;林后农地土壤含水量有恢复趋势,年平均恢复速度为15 mm左右,其土壤含水量要恢复到持续农地当前的水平,大约需要40a的时间。研究结果揭示了黄土丘陵半干旱区人工林对土壤水分影响的长期性,并为制定可持续的土地利用规划提供借鉴资料。

       

      Abstract: Planted forests can deplete deep soil water, forming an obstacle to sustainable land use in the semi-arid area of Loess Plateau. The purpose of this study was to examine effects of grazing and cropping on replenishment of deep soil water where forest plantations had depleted soil moisture at depths of 2~9.9 m. We compared soil moisture on plantation plots with that on plots where plantations were replaced by crops, grazed grassland, and ungrazed grassland seperately. Over a 20-year period there was no increase in soil water content in the grazed grassland at depths of 2~9.9 m. There was a small increase(0.5~3.7 mm/a) in soil water content in the protected grassland, however the slow rate of increase suggests that at least 150 years would be needed for ungrazed grassland soils to regain water content similar to that present prior to planting trees. Recharge of deep soil moisture was faster in cropland(15 mm/a), but at this rate it would still take about 40 years to restore cropland soil water content to pre-plantation conditions. The results of this study reveal long-term ecological effects of artificial forest in this water stressed area and give useful information to sustainable land use planning.

       

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