群落尺度植被水土保持功能评价模型的构建——以大别山北麓安徽省金寨县为例

Construction of Evaluation Model for Soil and Water Conservation Function of Vegetation at Community Scale--Taking Jinzhai County,Anhui Province at Northern Foot of Dabie Mountains as an Example

[目的]探索群落尺度植被水土保持功能评价模型,为大别山区植被水土保持与生态建设提供参考依据。[方法]基于已有研究通过文献计量法、专家经验法筛选建立植被水土保持功能初选指标(包括植被类型、植被结构、地形等30项)。通过野外调查获取指标实测值,利用随机森林法、决策树法分析、衡量各指标,以指标实测值与土壤侵蚀量建立多元逐步回归关系,构建群落尺度植被水土保持功能评价模型。[结果]基于随机森林的全局回归建模(R^(2)为0.71)较决策树的局部回归建模(R^(2)为0.69)效果更优。基于随机森林全局回归方式,构建了包括坡度、林龄、灌木盖度、草盖度、枯落物厚度5项指标的评价模型。植被水土保持功能为:防护林(0.705)>用材林(0.529)>经济林(0.513)>灌草(0.457)。[结论]在群落尺度植被水土保持功能评价中,随机森林法所构建的模型其应用性、可操作性较强且易于掌握。

[Objetcive]An evaluation model for the soil and water conservation function of vegetation at community scale was explored in order to provide a reference for soil and water conservation and ecological construction of vegetation in the Dabie Mountains.[Methods]Based on existing research,through the bibliometric method and expert experience method,the primary selection index for soil and water conservation function of vegetation was established,including 30 items characterizing vegetation type,vegetation structure,terrain,and so on.The measured values of the indicators were obtained through field investigation,and the indicators were analyzed and measured by the random forest method and the decision tree method.A multiple stepwise regression relationship between the measured values of the indicators and soil erosion was established to construct an evaluation model for soil and water conservation function of vegetation at community scale.[Results]A global regression model based on a random forest(R^(2)=0.71)was better than the local regression model based on a decision tree(R^(2)=0.69).Based on the global regression model of random forest,an evaluation model which included slope,forest age,shrub coverage,grass coverage,and litter thickness was constructed.The soil conservation functions of vegetation in the study area followed the order of protection forest(0.705)>timber forest>(0.529)economic forest(0.513)>shrub-grass(0.457).[Conclusion]In the evaluation of vegetation soil and water conservation function at community scale,the model constructed by random forest method has strong applicability,operability and is easy to grasp.