基于水分平衡的黄土区小流域防护林体系高效空间配置

Arrangement of protective forest system in gulled-hilly loess area based on water balance.

该文对黄土残塬沟壑区和丘陵沟壑区小流域防护林体系高效空间配置问题进行探讨 .针对影响水土流失的主要因子———降雨、地形与小流域侵蚀泥沙的来源及水土流失发生发展规律 ,提出以小流域为单元 ,基于林水平衡 ,体现水土保持功能持续提高的水土保持体系高效空间配置原理与技术 .小流域防护林体系的配置模式为 :①当坡面的坡度 <2 5°时 ,营造农地防护林 ,坡面防护林 ,农林复合经营 ,复合农林业经营模式包括隔坡梯田、隔坡水平沟、水平梯田 .隔坡面以经济树种为主 ,隔坡长与田面宽应根据生态经济原则确定 ,坡面防护林以防止地表股流的冲淘侵蚀为主 .②当坡面的坡度 >2 5°时 ,应发展林牧业 ,采取林草复合 ,封山育林与人工种植相结合的治理模式 .③沟谷地配置固沟拦沙滤水林模式 ,降低流速 ,减少冲力 ,拦沙滤水 .采取林草复合 ,封山育林与人工种植相结合 ,生物与工程相结合的治理模式 .防护林体系应基于小流域的水分生态环境合理分布 .防护林体系在不同地貌部位的合理配置应遵循不同立地的生物量允许值 ,林水平衡 ,适度造林 。

This paper studies the rainfall and topography which influence the soil erosion in the gulled hilly loess area, and analyses the sediment source and regularity of soil erosion according to the field monitoring data,puts forward arrangement patterns and techniques of protective forest system which is based on soil and water conservation function and moisture balance. ①When slope degree <25°,agroforestry system is adopted,including terraces separated by slopes,level channels separated by slopes and level terraces. Slope length and farmland width are designed in the light of the eco economic principles.② When slope degree >25°,the lands may be used for forestry and husbandry,the measures include combination of trees and grass planting,closing the land for reforestation and artificial tree planting.③Building a protective forest pattern in valleys and channels to stabilize channels, hold up sediments and filter water,decrease flood peak and reduce velocity of flow.The concrete measures are combinations of forest and grass,closing hill and at forestation as well as artificial planting, also the combination of biological and engineering measures.The arrangement of protective forest system should base on the rational distribution of moisture ecological environment,that is the planting of protective forest system on different topography considering the permission biomass of specific site condition and the balance between forest and moisture,so as to reach the rational planting arrangement pattern and stable stand structure.