北方土石山区石堰梯田的水土保持作用

Soil and Water Conservation Capacity of Stone-dam Terrace Rocky Mountain Areas in Northern China Supported by RUSLE

北方土石山区的石堰梯田土地管理模式被认为能够有效地保持水土、提升土壤地力、增加农田生产力,但是该模式的具体水保效益以及生态学机制尚不清楚。因此,本文以河北涉县旱作石堰梯田为研究区,利用GIS和RS技术,以及修正的通用土壤流失方程(RUSLE)估算了研究区2000-2005年、2006-2011年和2012-2017年三个阶段的石堰梯田土壤侵蚀量和保持量,得到了研究区土壤侵蚀量的空间分布特征,并通过原位观测实验对研究区石堰梯田的水土保持措施因子P进行校正。结果表明:石堰梯田区的水土保持能力良好,相较自然条件(无耕作措施),可减少泥沙流失量91.5%左右。此外,石堰梯田系统的土壤侵蚀量低于林地和草地的土壤侵蚀量。就区域尺度而言,2000-2005年、2006-2011年和2012-2017年三个时期的年均土壤侵蚀模数分别为14925、9495和82783 t·km^-2·a^-1。根据土壤侵蚀的分类分级标准(SL19090),石堰梯田系统基本为微度或轻度侵蚀。由于石堰梯田耦合了花椒树边际种植模式,其土壤保持量也远高于其他土地利用方式。研究成果将为雨养农业生产和山区生态环境保护提供参考。

Terracing using stones is believed to be effective for water and soil conservation,improving the soil fertility and agricultural productivity in rocky slopes of northern China,but the ecological mechanisms for this land conservation practice to prevent soil and water loss remain unclear.In this study,the soil loss and soil conserved by stone-terraces for the period of 2000-2005,2006-2011 and 2012-2017 at She Country of Hebei Province was estimated using the Revised Universal Soil Loss and Erosion model(RUSLE)together with RS and GIS technique.The soil and water conservation scalar in the RUSLE model was calibrated by our on-site experiment.Soil loss maps were made for the three periods.Results showed that the soil and water conservation capacity of terraced fields were much higher than those of natural condition(no-tillage measures),which can reduce the soil loss by 91.5%.The efficiency of stone-terracing was lower than grassland and woodland in terms of soil loss conservation.The erosion modulus was 14925,9495 and 82783 t·km^-2·a^-1 at 2000-2005,2006-2011 and 2012-2017,respectively.The severity of soil loss for stone terraces can be categorized as trivial or slight according to Standards for Classification and Gradation of Soil Erosion(SL19090).The soil conserved by terraces was much higher than other water and soil conservation practices when economic tree species grow on the boundary of terraces.Our findings will provide reference and role model for the rain-fed agricultural production and environmental protection in this region.