北方土石山区坡耕地水土保持措施的空间有效配置

坡耕地是北方土石山区水土流失的重要策源地,为了有效防治坡耕地水土流失,提高坡耕地持续利用,分析了不同水土保持措施在坡耕地上的适用范围,研究结果显示,耕作措施的水土保持效益随着坡度的增加而降低,在0°~6°的坡度范围内水土保持效果最佳;坡改梯工程的适用范围广泛,水土保持效益稳定,但在陡坡上实施坡改梯工程的难度和成本将显著增加,维护费用高,且土地的损失量大,不宜在土地资源紧张的贫困山区大面积推广;植物篱措施的水土保持效益受坡度的限制性小,在25°以下的坡地上都能收到良好的水土保持效果,且投资少,适合在在广大贫困山区使用。因此,根据北方土石山区的坡耕地的特点及不同水土保持措施最佳适用范围,坡耕地被划分为4个坡度范围分别进行水土保持措施的优化配置,即0°~5°平地及浅丘地采取以耕作措施为主进行治理,5°~15°缓中坡耕地采用以梯田措施为主、植物篱措施为辅进行治理,15°~25°的坡耕地采用植物篱措施为主进行治理,25°以上坡耕地必须退耕还林还草。

Study on optimized patterns of soil and water conservation measures on sloping fields in earth-rocky mountainous area of northern China

The important source of soil and water losses is sloping fields in rocky area of northern China. In order to reduce soil and water losses in sloping fields and improve sustainability on fragile slopes, the applied range of different soil and water conservation measures in sloping fields was researched. The results showed the larger the gradient of sloping fields is, the less the soil and water conservation benefits of farming measures are, and the optimized benefits could be achieved on slopes of 0°~6°.Terrace measures had a larger applying range, and their water conservation benefits were higher and steadier. However, the cost, difficulties, and land loss rate would be increasing observably with the increase of slope. At the same time, the level terrace with higher standard is not suitable for larger area extension in a poor mountainous area. Hedgerows measures could be used on slopes less than 25°, and the investment was less, which was fit in a poor mountainous area. Therefore, based on characteristics of sloping fields and the optimal range of different soil and water conservation measures in rocky area of northern China, the sloping lands were partitioned for 4 slope ranges to collocate different soil and water conservation measures, that is, farming measures were the main pattern for sloping fields with gradients from 0° to 5° , terrace measures were the main pattern for sloping fields with gradients from 5° to 15°, hedgerows measures was the main pattern for sloping fields with gradients from 15° to 25°.For sloping fields with gradients over 25°,the converting cultivated land into forests or grassland program must be put in practice.