Comprehensive Evaluation Of Stability Of Pinus Tabuliformis Plantation In Huanglongshan Mountain Based On Six Methods

For plantation stability,the evaluation methods are mostly limited to one or two,and there is less research on the classification of stability results.This article takes the Pinus tabulaeformis plantation in Huanglongshan mountain as the research object,and establishes a comprehensive evaluation index system for the stability of Pinus tabulaeformis plantation by consulting experts and consulting a large amount of literature.Based on field survey data and indoor laboratory analysis data,comprehensive evaluation methods such as Analytic Hierarchy Process(AHP),Subordinate Function(SF),Principal Components Analysis(PCA),Grey Relational Analysis(GRA),Stability Degree Index(SDI)are applied,and comparison with the M.Godron method and forest community stability evaluate methods by internal state and neighborhood environment(FCS)(Comprehensive Evaluation of Internal and External Evaluation),to evaluate the stability of different types of Pinus tabulaeformis plantations in Huanglongshan mountain.The methods of fixed interval evaluation,dynamic interval evaluation and cluster analysis are used to classify the evaluation results respectively.The advantages and disadvantages of different evaluation methods and different classification methods are discussed.The method and direction for future stability evaluation are pointed out to guide the management of Pinus tabulaeformis plantations in Huanglongshan mountain.The main conclusions of the study are as follows:(1)Establish a comprehensive evaluation indicator system for the stability of plantation,includes 14 indicators from species diversity,site conditions,stand structure and vitality that reflect the resistance,resilience and persistence of community: tree layer diversity,shrubs layer diversity,herb layer diversity,terrain factor,soil physical properties,soil chemical properties,litter thickness,stand density,population age structure,horizontal spatial structure,vertical stand structure,population regeneration potential,aboveground biomass,stand health status.(2)According to the age group,slope direction and origin,25 plots of Pinus tabulaeformis plantation in Huanglongshan mountain were divided into six stand type: the stability of each stand type is as follows: natural forest in sunny slope(NS)is superior,mature forest in cloudy slope(MC)is good,submature forest in cloudy slope(SC)is normal,and submature forest in sunny slope(SS),half-mature forest in cloudy slope(HC),and half-mature forest in sunny slope(HS)are poor.With the development of plantation stands,its stability is getting better and better,and it is closer and closer to the state of natural forest.(3)According to the stability evaluation results,the six comprehensive evaluation methods can be divided into three categories: the first category is AHP,SDI and GRA,and the maximal value standardization method is adopted;the second category is SF and PCA,and the standardization method of fixed index range is adopted;the third category is FCS with different index systems;the differences in the index system and the choice of standardized methods will have a greater impact on the results.For the M.Godron method,using the Hossfeld growth curve fitting effect is better,and the use of a fixed evaluation interval is also better for the classification of stability,but it is not suitable to use it to study the overall stability of the plantation,and should focus on the study of the tree layer stability,stability of shrub layer and herb layer can be used as reference.AHP,GRA and SDI,respectively,assign values to the weight of each index from the subjective experience,the average distribution,and the objective angle,then evaluate the stability,the stability results have greater similarities,these three methods must be selected in the future stability study.On this basis,selecting a variety of classification methods for comparison can ensure the objectivity of the classification results.(4)The Simpson diversity index,Alatato evenness index and Menhinick richness index of tree layer have significant positive correlation with the stability value of plantation community.The Menhinick richness index of shrub layer has a significant negative correlation with the stability of plantation community.There was a significant positive correlation between Simpson diversity index of herbaceous layer and community stability of plantation.The evaluation of tree layer diversity was more important to the stability of plantation community.To a certain extent,diversity-stability theory was supported.(5)For the Huanglongshan forest area,the stability of the half mature forests and submature forests of Pinus tabulaeformis plantations is poor,and the tending measures are urgently needed to improve the structure and the single tree species,and to protect the broad-leaved tree species;Improve the dense structure of tree layers,provide growth space for under-forest shrub layers,and improve the regeneration environment of young seedlings;At the same time,it is necessary to appropriately clear the litter with large thickness under the stand and provide the propagules of the arbor species with the conditions for contact with the soil to germinate,so that the plantation stands will at a direction to complex layers,different ages,and mixed natural forests.