摘要
选择我国西南山地典型人工林为对象,调查全山坡人工林的植被盖度及根系密度,利用137Cs示踪技术确定人工林坡地土壤侵蚀速率,探讨人工林坡地植被盖度及其细根与土壤侵蚀的关系。结果表明:整个人工林坡地表现为严重土壤侵蚀,侵蚀速率达25.25t/(hm2·a)。不同类型植被覆盖下土壤侵蚀再分布速率为祼地(-36.32t/(hm2·a))<乔木(-0.57t/(hm2·a))<灌木(0.53t/(hm2·a))<草(0.60t/(hm2·a))。回归分析表明,人工林坡地土壤侵蚀速率与植被盖度无显著相关性,土壤侵蚀速率随<1mm的植被细根密度的增加而降低,二者之间呈显著负相关关系(P<0.01),但与>10mm径级的植被粗根密度没有显著相关性。人工林地植被细根控制土壤侵蚀的有效性可以用植被细根密度与土壤再分布速率的关系方程来定量评价。当植被细根密度为60～100g/m2时,可以看作人工林植被防蚀拦沙的有效根密度。结果表明,植被细根在控制坡地土壤侵蚀比植被盖度更为重要。因此,禁牧保护植被细根是控制人工林地土壤侵蚀与土地退化的有效措施。
Selecting a representative forest hillslope in Xichang,southwestern China,the coverage and root densities of different species vegetation were surveyed.Soil erosion and deposition rates under different vegetation cover were determined through measurements of 137Cs.Soil erosion was severed with an average of erosion rates of 25.25t/(hm2·a)in the entire hillslope.The order of soil redistribution rates under different vegetation types was bare land(-36.32t/(hm2·a))<tree(-0.57t/(hm2·a))<shrub(0.53 t/(hm2·a))<grass(0.60t/(hm2·a)).Regression analysis showed that there was no significant correlation between soil erosion rate and coverage of vegetation in planted forest hillslope.Soil erosion rates decreased with the increase of fine root density with the diameter less than 1mm in planted forest hillslope,and they had a negative correlation each other(P<0.01),but did not change significantly with coarse root densities with the diameter greater than 2mm.Effects of plant roots on soil erosion and deposition could be quantified with the relationship curve of Rd and soil redistribution rates in planted forest hillslope.The range(60～100 g/m2)of root density might be as the effective root density for vegetation in reducing soil erosion and trapping sediments from the upland.These suggested a significant role of fine plant roots in controlling forestland erosion and trapping sediments from the upland relative to vegetation cover.Therefore,protecting fine root systems through forbidding over grazing should be considered effective measures to control soil erosion and land degradation in planted forest hillslope.
出处
《水土保持学报》
CSCD
北大核心
2013年第4期29-33,共5页
Journal of Soil and Water Conservation
基金
国家自然科学基金项目(41171231
31000944)
国际原子能机构项目(IAEA 15479
15938
16941
16290)
