对当代林业水土保持作用的几点认识

Role of Forest in Current Soil and Water Conservation

水土保持林不同于一般意义上的森林 ,其布局、配置、树种结构、经营及其发挥的水土保持能都具有本身的特殊性。水土保持林的效益主要取决于林地枯落物和林地土壤状况。对湖南、江西两省水土流失概况的调查结果表明 ,尽管森林覆被率高达 5 1 4%和 5 3 % ,林地中的水土流失仍十分明显。原因是目前的森林质量和功能都无法与具有水土保持功能的原始森林相比 ,其地表组成物质太少且单一 ,地面粗糙度低 ,起不到对地表径流的阻挡作用 ,致使地面径流汇流时间缩短 ,洪水下泄快并容易形成洪水叠加 ,导致洪涝灾害加剧。同时 ,应该承认森林效益具有迟效性 ,指望现代营造的、还不完全具备水土保持林功能的“假森林”在短期内发挥效益是不现实的。只有采取水土保持综合治理 ,才能有效地减少水土流失。

Soil and water conservation forest, which has special characteristics in distribution, layout, variety structure, management and soil conservation role, is different from general forest. Effect of soil conservation forest depends on land surface cover of dead leave and soil condition. Investigation of soil and water loss in Hunan and Jiangxi provinces shows that there are still evident soil and water loss under forest even through the forest cover rate is as high as 51.4% and 53% respectively. The reason is that the quality and function of current forest can not match the natural primeval forest with perfect soil conservation effectiveness.Because unitary surface material and less land surface roughness which can not retain runoff lead to short confluence time, quick delivery of flood, easy superposition of floods,and result to flood disaster. At the same time, it should be acknowledged that forest effects are normally coming late, and it is not realistic to hope the current planted“false forest', which has not yet hold the full soil conservation function, to make effects in short period. Only through comprehensive harness of soil and water conservation can soil and water loss be reduced efficiently.