Intraspecific and interspecific competition of Larix olgensis plantations in different age groups

ObjectiveThrough quantitative analysis of intraspecific and interspecific competition of different age groups of larch plantations, the dynamic changes of forest tree growth in different age groups were revealed, which provided scientific basis for the sustainable management of Larix olgensis plantation.

MethodThe investigation of larch subject trees and competitor trees in 6 plots of Jingouling Forest Farm of Wangqing Forestry Bureau in Jilin Province, northeastern China was conducted. Using the Hegyi simple competition model, the intraspecific and interspecific competition of different age groups of larch plantations was studied; a total of five models, including the logarithmic, binomial, power function, index, and logistic model, were used to fit the relationship between the total competition index and the DBH of larch subject trees.

Result(1) The intraspecific competition index of the plots a, b, c, d, e, and f accounted for 86.40%, 92.81%, 61.97%, 77.18%, 81.42%, and 93.70% of the total competition index, the intraspecific competition was the main form of the tree competition. (2) The distribution of every species in each plot was not the same, and there was a large difference in the interspecific competition index, and there was no certain regularity. (3) The relationship between DBH and competition index of larch species in middle-aged and near-mature forests obeyed the power function. The relationship between DBH and competition index of mature larch subject trees obeyed an exponential function, and the competition intensity decreased with DBH increasing of the subject trees. When the DBH of subject trees in middle-aged forest reached 20 cm, the competition index declined stably. At this time, the subject trees was less competitive; when the DBH of subject trees in near-mature forest was 25 cm, and the DBH of subject trees in mature forest was 30 cm, the subject trees were less competitive.

ConclusionThe competition of Larix olgensis plantation mainly comes from intraspecific competition, and the competition index decreases with the increase of DBH.