Structured Management Model Of Main Forest Types In Maoershan Natural Secondary Forest

As the main body of my country’s forest resources,natural forest have the values of conserving water sources,maintaining species diversity,providing timber and related forest products,and maintaining the stability of the ecosystem.Under the long-term artificial and natural disturbance,the original top plant community in the forest area of Maoershan has degenerated into a secondary community dominated by natural secondary forest.The community was significantly different from the original forest in terms of forest productivity,natural regeneration,stand structure and stand quality.Therefore,only by having a deeper understanding of the structural state characteristics of the main stand types in this region,and making reasonable supporting management models according to the unique structural characteristics of different stand types,can we gradually improve the stand quality and accelerate the rate of forest succession in this region.This paper takes different forest types of Maoershan natural secondary forest(soft and broad-leaved mixed forest,soft and hard broad-leaved mixed forest,hard broad-leaved mixed forest,Mongolian oak pure forest)as the research object,based on the survey data of 51 permanent sample plots in 2016 and 2020,selecting ten stand structure indicators from two angles of stand structure and stand vigor,and the stand structure status of different stand types is comprehensively evaluated by constructing a unit circle comprehensive evaluation system.The canopy density of the sample plot was taken as the constraint condition and combined with the P value of the single tree comprehensive tending cutting index to determine the optimal tending cutting intensity of the plot.Using the forest spatial structure index(FSSI)and forest spatial structure distance index(FSSD)to real-time evaluation of forest simulation the effect after the operation,according to the existing forest stand structure evaluation-design-real-time assessment of business process,summarizes the four main forest types of structured management models.The main conclusions finally obtained are as follows:(1)By selecting stand structure indicators(stand level rate,uniform angle,diameter distribution)and stand vitality indicators(tree species diversity,stand volume,stand spatial dominance,stand potential density,target tree species dominance,tree stability and proportion of healthy trees)10 indicators,construct a unit circle comprehensive evaluation system to analyze the actual forest stand structure status,and divide the sample plots into different evaluation levels.The results showed that the comprehensive evaluation grades of soft and broad-leaved mixed forest were good(17%),medium(11%),poor(67%)and extremely poor(5%);the comprehensive evaluation grades of soft and hard-leaved mixed forest were good(13%),medium(19%),poor(62%)and very poor(6%);the comprehensive evaluation grades of hard and broad-leaved mixed forest are good(10%),medium(60%)and poor(30%);The comprehensive evaluation grade of Mongolian oak pure forest is medium(43%)and poor(57%).The best and worst stand structure states are respectively soft and hard broad-leaved mixed forest RYK03(ω=0.53),hard broad-leaved mixed forest YK02(ω=0.53)and soft broad-leaved mixed forest RK07(ω=0.24);(2)The simulated tending cutting process was compiled with VBA to determine the optimal tending cutting intensity in the plots.The results showed that the optimal cutting intensity of soft and broad-leaved mixed forest,soft and hard broad-leaved mixed forest,hard and broad-leaved mixed forest were 30%,and Mongolian oak pure forest were 10%due to low initial canopy closure,and the increase rates of P value of each stand type were 11.9%,9.8%,7.5%and 5.0%,respectively.(3)The effect of simulated forest management was evaluated by calculating stand spatial structure index(FSSI)and stand spatial structure distance index(FSSD).The results showed that with the increase of simulated cutting intensity FSSI gradually increased,while FSSD gradually decreased,indicating that the realistic stand structure gradually approached to the ideal stand structure.The real stand spatial structure is more reasonable and closer to the ideal spatial structure state of hard broad-leaved mixed forest.(4)The structured management models of different stand types were summarized from realistic stand characteristics,the reasonable index range,optimal tending and cutting intensity,structured management design and ultimate objective structure of main stand types.