| With the economic development of human society and the continuous deterioration of the ecological environment,the ecological,social and economic benefits of ecological public welfare forest,which is influenced by the health status of forest,had been getting more and more attention.Qinghai Province,one of the important areas of ecological environment protection in China,has carried out Three-north Forest Protection Project,Natural Forest Protection Project,Conversion of Farmland to Forest(grass)Project and key ecological public welfare forest construction project,which has improved the ecological environment greatly.However,many problems such as alpine arid and unreasonable stand structure had made poor growth and regeneration of stand,soil drying and damage of disease,insect and rat,having negative influence on ecological service function of ecological public welfare forest in this area.Taken ecological public welfare forest of high-cold areas on loess plateau in Datong,Qinghai as object of this study,the health evaluation system of public welfare forest in high-cold areas was built based on the survey and analysis in field sample plots and combined with relevant expert opinions.We made health evaluation on public welfare forest in Ta’ergou,Qiaotouzheng and Huangjiazhai forest farm,and put forward corresponding healthy management countermeasure.The main results are as follow.(1)Taken forest stand as study scale,health evaluation index system of ecological public welfare forest in loess plateaus of Qinghai was built up from five aspect of forest stand structure,stand productivity,stand resistance,site condition and service function.Index,divided into quantitative and qualitative categories,was made standardized processing by extremum method and rank assignment respectively.(2)The weight of the evaluation index is determined by the subjective and objective comprehensive weighting method combined with the analytic hierarchy process and the entropy weight method.The results show that the top five weights of index are community hierarchy(0.1203),soil water content(0.0945),pest and disease level(0.0827),annual net growth(0.0635),and soil and water conservation(0.0502),which belong to forest stand structure,site condition,forest stand resistance,forest stand productivity and service function.(3)The health index was calculated by comprehensive exponential model and health levels were divided.The results show that the average health index of all plots was 0.54,and the ecological public welfare forest was in a sub-health state as a whole.Among the 34 standard plots surveyed,the grades of high quality health,good health,health,sub-health and unhealthy plots number were 2,3,8,19 and 2,whose proportion were 6%,9%,23%,56%and 6%.Different ages and different forest types of ecological public welfare forests were evaluated.The health status of middle-aged forests was better than that of young forests;the health status of mixed forests was better than that of broad-leaved forests,broad-leaved forests were better than coniferous forests,and mixed forests of spruce and white birch were the most healthy ecological public forest types.(4)Combined with the health scores of each ecological public welfare forest in the five aspects of stand structure,stand productivity,stand resistance,site conditions and service functions,the room for improvement of health degree was judged.Furthermore,the specific improvement measures were put forward.(5)According to the common problems of ecological public welfare forests in the study area,combined with the results of health assessment and the relevant experience of health management of ecological public welfare forests at home and abroad,the health management strategies suitable for ecologieal publie welfare forests in the study area were proposed,including forest tillage,pest eontrol and forest fire prevention. |
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