| Masson’s pine is a pioneer tree in soil erosion area because of its drought resistance and poor growth resistance.The problem of single undergrowth vegetation and simple undergrowth spatial structure is still serious in the pure forest of masson’s pine artificially constructed.The soil beneath the masson pine forest is subject to climate,Due to the influence of various factors such as vegetation and lithology,hydraulic erosion is very easy to occur,and the soil erosion severity is second only to that of China’s loess plateau.Soil erosion not only results in the loss of soil nutrients such as C,N,and P,but also reduces the number of camps needed for plant production and developmentNutritive substances also limit the productivity of vegetation communities and further aggravate the degree of soil erosion.In order to solve the problems of the masson pine forests of soil erosion is serious,of pinus massoniana stand close to nature management measures,through the close to nature management implementation of forest stand comparison with corresponding controls,as well as the quantitative evaluation of the following three problems: 1,how to build a close to nature management horsetail pine forest benefit evaluation index system of soil and water conservation? 2.To understand the changes of soil and water conservation benefit indexes between the control group with near-natural management measures and the control group without management measures,and to analyze the reasons leading to such changes.3.Quantitative evaluation of ecological benefits of soil and water conservation between near-nature management measures and comparative management measures.Preliminary results are as follows:1.close to natural pine as the study area,build the DPSIR model(conceptual framework)from the original intention of close to nature management measures and hoped to achieve the purpose of the driving force of the pine forests,close to nature management pressure,the current state of forest stand,impact and response were analyzed,and compiled the index can be dividedinto four categories: improve soil function,corrosion resistance,conductivity and undergrowth.A total of 41 evaluation indexes were selected to evaluate the ecological benefits of soil and water conservation of pinus massoniana forest in guiyang city,and 29 evaluation indexes were screened and determined by principal component analysis,which constituted the evaluation index system of ecological benefits of pinus massoniana forest in guiyang city.2.Variation characteristics of different near-natural management evaluation indexes:(1)soil function: the comprehensive score of soil function was ranked as: > near-mature forest cutting,> near-mature forest cutting,> medium age forest tending,> medium age forest thinning,> medium age forest tending,> medium age forest tending;The characteristics of soil function change were studied from two aspects: soil physical properties and soil chemical properties.Compared with the corresponding control group,the soil non-capillary porosity of masson’s pine stand under near-natural management decreased and the soil capillary porosity increased.However,because soil capillary pores are easy to be occupied by soil water,poor ventilation and easy accumulation of organic matter and other chemical elements,the soil chemical properties of masson pine stand will be improved compared with the control group after the nearly natural management measures are implemented.(2)soil erosion resistance: the comprehensive evaluation of soil erosion resistance was ranked as following: the rearing of young forest > compared with the rearing of young forest >compared with the cutting of near-mature forest > compared with the cutting of near-mature forest > compared with the thinning of medium age forest > compared with the thinning of medium age forest.Soil corrosion resistance was analyzed from three aspects: mechanical stability aggregates,water stability aggregates and soil mechanical composition.It was found that after the implementation of near-natural management measures,the content of 5mm grain size aggregates in near-mature forests and young forests increased,while the content and stability of <0.25 mm grain size aggregates decreased,and the overall stability of soil aggregates increased.However,the overall stability of soil aggregates decreased after thinning of masson’s pine stand in mid-age forest,and the content and stability of soil aggregates in >5mm grain size aggregates and<0.25 mm soil aggregates were opposite to the former.Analysis of soil structure and net growth of stability of masson’s pine aggregates under different near-natural management was as follows:thinning of > medium age forest in young forest tending and thinning of > near mature forest were consistent with the distribution characteristics of soil mechanical stability aggregates.Soil water infiltration performance:(3)comprehensive score sorting for the sapling forest soil water infiltration capability control > mid-maturation forest thinning > mid-maturation forest thinning control > > nearly ripe forest logging,nearly ripe forest felling control > sapling forest,close to nature management of horsetail pine forest in addition to the sapling forest and the control group,the rest of the horsetail pine forest after close to nature management measures of soil water infiltration capability were greater than the corresponding control group.(4)undergrowth of undergrowth vegetation: the order of undergrowth of masson’s pine forest under different near-natural management was as follows: undergrowth of near-mature interforest thinning > medium age interforest thinning > medium age interforest thinning > medium age interforest thinning b> medium age interforest thinning > medium age interforest tending control.In the growth and change of undergrowth vegetation,the most beneficial effect was achieved by cutting pinus massoniana in the near-mature forest,followed by the cultivation of the young forest,and the least beneficial effect was achieved by thinning pinus massoniana in the medium age forest.3.in this paper,the different horsetail pines under the close to nature management measures of soil and water conservation ecological benefit of quantitative evaluation using is the combination of subjective evaluation and objective evaluation method,in the process of evaluation based on analytic hierarchy process(ahp)and entropy weight method and data statistics to analyze the three ways to end,ahp method and entropy weight method were given a weighting of 25% and 75%.After standardized treatment of the results obtained by the two methods and the corresponding weights,the total evaluation values of the three near-natural management measures and their corresponding control groups were as follows: young forest tending control group >medium age forest thinning control group > medium age forest thinning control group > medium age forest thinning control group > medium age forest thinning control group > young forest tending control group.The order of net growth rate of the three near-natural management measures is as follows:(1)medium age(>)medium age(>)medium age(>)medium age(>)medium age(>)medium age(>)In addition to the nursery of the young forest and the control group of masson’s pine forest,the order of masson’s pine forest and its control group in the near-natural management of masson’s pine forest is the control forest of >,which indicates that the near-natural management of masson’s pine forest can improve the ecological benefits of soil and water conservation.The physical and chemical properties of soil are the material basis for determining other properties of different stands,and the evaluation indexes are inextricably related to the physical and chemical properties of soil. |
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