Correlation Between Growth and Spatial Structure of Dominant Trees in Larix gmelinii var.principis-rupprechtii Plantations at Different Ages
[Objective]The growth of dominant trees is closely related to that of their neighboring trees,and exploring the influence of the spatial structure characteristics of the neighboring trees in differently-aged forests on the growth of target trees can provide a theoretical basis for adjusting the spatial structure to stimulate the growth potential of forest stands.[Methods]We selected three Larix gmelinii var.principis-rupprechtii plantation stands in different ages(27,37 and 46 years),and set up large sample plots of 90 m×60 m,120 m×120 m and 120 m×120 m,respectively.Took the dominant tree and its 4 nearest neighbor trees as the spatial structural unit,calculated the indexes of uniform angle index,dominance,mingling and crowding of each dominant tree,and analyzed the growth differences of dominant trees among different spatial structures in the stands with different ages.[Results]The average annual increase of diameter at breast height(DBH)and tree height(H)of dominant trees were significantly different among forest ages,and the average annual increase of DBH and H decreased with the forest age rising.In the structural unit of the 27-years stand,the proportion of dominant trees with the random distribution,dominant,zero mixed,and crowded state was the highest.The mean DBH of dominant trees was the greatest at a uniform angle index of 0.50,a dominance of 0,a mingling of 0.75,and a crowding of 1,respectively,and the mean tree height of dominant trees was the greatest at a uniform angle index of 0,a dominance of 0,a mingling of 0.75,and a crowding of 0.75,respectively.In the structural units of the 37-years stand,the dominant trees in random distribution,dominant,zero mixed and very crowded state had the highest proportion.The mean DBH of dominant trees reached the maximum when the uniform angle index was 0.50,the dominance was 0,the mingling was 0.50 and the crowding was 0,respectively,and the mean tree height of dominant trees was maximum when the uniform angle index was 0,the domiance was 0,the mingling was 0.25 and the crowding was 1,respectively.In the structural units of the 46-years stand,the proportion of dominant trees in random distribution,dominant,zero mixed and sparse state was the highest.The mean DBH of dominant trees was the largest when the uniform angle index was 0.50,the dominance was 0 and the crowding was 0,respectively,and the mean tree height of dominant trees was the largest when the uniform angle index was 0,the dominance was 0 and the crowding was 0.[Conclusion]Horizontal distribution pattern,tree species diversity,individual size and crown competition affect the growth characteristics of dominant trees.In the process of succession,the dominant trees developed in the direction of reducing aggregation degree and competition pressure,and appropriately increasing the mixing degree of the dominant trees and ensuring the growth advantage of the dominant trees were conducive to the growth of their DBH and tree height.In the quality selection stage,it is advisable to further select the superior trees with good growth as the target trees,properly tending and felling,optimizing the structural units,and improving the stability of the stands by means of artificial promotion of natural regeneration.In the near natural stage,dead trees should be cleaned up in time,and the spatial structure should be optimized by artificially promoting natural renewal and removing interfering trees.
NETL
NSTL
万方数据
维普
