Spatial Cluster Analysis And Replanting Optimization Of Natural Secondary Forests In The Greater Xing’an Mountains

Replanting and cutting are two opposite spatial optimization methods.In order to accelerate the natural succession of natural secondary forests in the Greater Xing’an Mountains and improve the quality of the forest,this paper takes three typical and different succession types of the forest types in the Greater Xing’an Mountains:white birch pure forest,white fall Mixed forests and mixed forests of larch and coniferous trees were used as raw data.The spatial pattern of the three forest types was analyzed using the Plotkin’s spatial clustering algorithm.Based on the ecological definition of canopy connection proposed by Larson,the spatial pattern analysis of different forest types was determined.The distance scale defines the spatial and temporal reference conditions for replanting optimization,optimizes the spatial pattern of secondary forests,further explores the species,number,and location of replanted natural secondary forests,and provides theoretical basis for production practice.The main conclusions are as follows:1)Under the condition of 99%confidence,there was no significant difference in soil thickness among the three stand types.At layer A1,there was no significant difference between the elements of pure birch and white-fall mixed forest.The white-fall mixed forest and larch coniferous mixed forest had significant differences in PH and total potassium content,and there were no significant differences in total nitrogen,total pHospHorus and total magnesium.In the A2 layer,the pure birch forest and the white-fall mixed forest had significant differences in PH and total magnesium content,and there were no significant differences in total nitrogen,total pHospHorus,and total potassium.There were significant differences among the contents,and there were no significant differences in total nitrogen,total pHospHorus and total magnesium.2)Using the Plotkin’s clustering algorithm to analyze the spatial pattern of three different forest types,it was found that as the distance scale increased,the individual distribution forests in the plot gradually decreased,the number of clusters increased first and then decreased,and eventually the entire forest land became a cluster.Under different plant number densities,the distance between the forest land and the same cluster were different.Based on the ecological definition of Larson’s canopy connection,analyze the differences in the number of clusters,the cluster size(the number of forest trees in the cluster),and the proportion of the number of forest trees of the same size cluster in the crown radius and different distance scales.As a distance scale for spatial pattern analysis,the distance can reflect the true cluster distribution of the forest land,and the distance scale of the spatial pattern should be determined for different forest types.3)Replanting and cutting are two opposite spatial optimization methods.In order to accelerate the natural succession of natural secondary forests in the Greater Xing’an Mountains,this paper selects larch as the replanting tree species,and considering the survival rate of the seedlings,the replanting was based on the young tree.Mainly,the replanting numbers of pure birch pure forest and white-fall mixed forest are 660 and 1970,respectively.After replanting,the pure birch forest and the reference forest land and the white-fall mixed forest were at the same distance scale,and the number of clusters,the cluster size,and the proportion of the number of trees in the same cluster are in the same distribution form.Under the scale,the number of clusters,the size of clusters,and the distribution of the proportion of the number of plants in the same cluster were consistent.Considering that this paper did not obtain the original data of the forest land in the next succession stage of larch and conifer mixed forests,no replanting management is carried out.After replanting,the proportion of larch in the sample plots increased significantly,which played a positive role in accelerating the succession of natural secondary forests in the Greater Xing’an Mountains.