干旱半干旱区径流调控造林技术研究

Study on Afforestation Technology through Runoff Regulation in Arid and Semi-Arid Regions

干旱半干旱区降水少 ,土壤水分亏缺 ,林木成活率低、保存率低、生长缓慢。径流调控造林技术以林木降水资源环境容量为基础 ,通过降水空间调控 ,改善林木土壤局部供水环境 ,以促进林木生长。据研究 ,在年降水量约 40 0mm的定西县 ,年降水保证率 75 %时 ,乔木密度保持在 40 0～ 160 0株 /hm2 、灌木密度保持在 70 0～ 190 0株 /hm2 能维持林木正常生长。据此进行了隔坡水平阶、水平沟、聚流水平坑、燕尾式鱼鳞坑等径流聚集工程布设优化设计 ,造林成活率和生长量显著提高。

In the arid and semi arid area, the precipitation is little, soil moisture insufficient and low survival rate, low preserved rate and slow growing of trees. Taking environmental capacity of rainfall resources of trees as a basis and through spatial regulation of precipitation, the technology of runoff regulation afforestation improves local water supply environment of soil of trees and promotes growing of trees. According to studies, in Dingxi County where annual precipitation is about 400 mm, the moisture can meet the requirements for normal growing of trees if the guarantee ratio of annual precipitation is 75%, density of arbor trees between 400～ 1 600 trees/hm 2 and shrubs density 700～ 1 900 plants/hm 2. Based on that it conducts optimization design on layout of runoff collecting works, such as terraced field with slope, leveled gullies, leveled pits and fish scale pits. The survival rate and growing speed have been greatly increased.