Grown Structure And Optimal Spatial Management For Secondary Forest In Maoershan Mountain

This study utilized 30 permanent sample plots and 176 stem analysis trees in Mao'er Mountain experimental secondary forest area which was investigated in 2007 and obtained 4237 sample trees,the died trees and sub-arbor trees were eliminated then the sample trees remained 3628;also 3401 branches data were measured among which 694 standard branches were gained.In all plots,diameter at breast height,tree height,crown width,coodinates and height to living crown base etc.were measured,besides,the detailed analysis of branches and foliage collection were conducted with 1 meter per sections of stem analysis trees.The individual tree crown ratio models for 10 major species epending on 2915 sample trees and the remaining 713 were used for validation were designed.Moreover,the branches analysis models for 10 species in secondary forest were established by the data of branch attributes, established crown profile models by analyzing insert positions of branch tips,and,established foliage models by cumulative percent of biomass in the relative crown length.Several spatial structure indices were dealed with and according to diversity mingling,aggregation index, competition index and crown area overlap index,a spatial structure optimizing model of secondary forest stand selective thinning was developed which can be solved by mathematic programming and apllied to the realistic stand.The primary works are below:(1)According to the analysis of tree size,competition and site in secondary stand,crown ratio models were developed for 10 species in the form of Logistic equation,and multiple coefficient was used to determine each factor groups contribute to the models.The parameters estimate results pointed that tree size and competiton between neighbour trees effect crown ratio greatly,whereas,site of stand effects little.All species crown ratio increase with diameter at breast height,as well as it with crown width and age of tree.The validation for each species crown ratio model indicats that the precision of prognose are all exceed 91%,also pass the Ftest except Betula costata and Acer mono.The value of deviation was all small especially mean error(ME) and mean absolute error(MAE).(2)Based on piecewise polynomial to develope 3 models of branch,there is a resulting close reletivity between branch diameter(BD) and the branch deepinto the crown(DINC),DBH, HT,and crown length(CL);3 branch models according to DINC,DBH,and HT as independent variables were provided;there is a high significance between branch chord length and branch length,the relationship can be described by the form of logarithm;a multiple linear equation was used to express the relationship between branch angle of origin and total DINC, DBH,crown radius and HT.Branch angle of origin generally distributed between 20 degree to 50 degree which can reach more than 60%in quantity,different spcecies had different proportion.Origin angle of branch less than 20 degree took 20%,there were few branchs with origin angle more than 60 degree,and seldom with angle between 70 to 80,furthermore,the angle bigger than 80 degree maybe resulted in measurement error.The distribution of branch angle was corelated to DINC of branch,the branch angle distributed in upper layer of canopy were generally small and with DINC increase the branch length of middle layer of canopy began to proglong,simultaneously,the weight of branch increased with branch diameter and length,hence,the branch angle of origin increased obviously and took the majority proportion. Howerver,in down layer of canopy the degree of branch angle were big all the same,the proportion was the smallest.The resulting branch diameter,branch length and branch chord length models were evaluated and appeared to behave well with high correlation coefficient and prognose precision.(3)This study considers the profile of broad-leaved species are not simply enlarged from the apex to crown base,depending on the stratified clip of branches the crown was divided into 2 parts,the first part was consisted of the upper and middle layer which could be developed the profile models of crown radius and relative height in the crown at a height of h in the form of cubic parabolic curve.Took lower layer of crown as the second part and used the similar parabolic curve in different forms to develope the profile models.All these forms performed crown profile for borad-leaved species well by geometry position of branch tips.(4)The tranditional three parameter Weibull distribution and others had no capability to describe the foliage distribution of broad-leaved species in secondary forest,other than Lognormal distribution.The cumulative distribution of foliage percent(CF%) and relative height into the crown(RPC) was found to follow a sigmoid shape from the crown base to the top of the tree in the study and performed well.The result pointed out that the vertical distribution of foliage for each species was different,however,generally speaking,the foliage in upper crown (0.3CL) for broad-leaved species in natural secondary forest took a small percentage,about 10%;in middle or middle lower of the crown(0.4CL to 0.8CL) the branches here took the majority percentage of whole foliage,almost 60%to 75%;but in lower crown(0.8CL),there was about 10%of whole foliage.(5)The interspecies competition of trees in secondary forest was expressed by Hegyi competitioin index,and the active competitor was calculated by the competition zone radius and the tree position,DBH,and distance in the zone,it was not all competitors in tranditional calculation.The study introduced crown area overlap index to describe the crown competition between subject tree and its competitors,furthermore,the crown area was classified into 5 levels with a method of equal crown projection area,therefor,the resulting crown area overlap index showed more realities of existing stand conditons.(6)Based on the theoretics of multiply divide,the spatial strcture optimizing model of secondary forest stand selective thinning was developed by diversity mingling,aggregation index,competition index and crown area overlap index,also designed 10 constraint conditions which were related to forestry meanings,the objective function was solved by the implicit enumeration method with LINGO 9.0,using 0-1 integer programming.(7)The model took M702 sample plot as an application example to specific every felled trees,and the value of objective function was changed quite significant which was increased more than 5 times after selective thinning,these proved that it satisfied the requirement of model design.Diameter class,species remained their steadiness while Shannon-Weiner index increased 3.5%.The value of q in constraint conditions decreased 6.6%,as the competition index and crown area overlap index decreased 19.99%and 50.93%respectively,howerver, the diversity mingling and aggregation index increased 2.5%and 4.1%respectively.The yield from felling less than the increment of stand and the volume decreased 27.03%.10 constraint conditions were all satisfied after the objective function solved which value increased obviously,these result reached the model design requirement as well as accorded with forestry meanings.This study,for the first time,established crown ratio models for natrual sencondary forest, besides,established branch analysis model acceptable for broad-leaved species by research branch attributes of major species in secondary stand,furthermore,the crown profile models for these trees were attempted to be developed,eventually,the results of these models obtained really good simulation.The study found out the crown area overlap index to describe the competition between crowns,these efforts quantified the ability to adapt light environment of broad-leaved species.Finally,the felled trees were determined and the spatial structure of stand was optimised in the application of example plot which showed characteristics of secondary forest in detail.The combination of forestry theories and practice will provide scientific,quantitative ideas for secondary forest decision-making,it is aslo a useful attempt to succeed and develope the tranditional forest management.