Objective In order to reveal the rule of dynamic changes of competition intensity within the community and the ecological adaptation mechanism, the intraspecific and interspecific competition of Pinus kwangtungensis were analyzed by investigating the 118 target trees and 253 associated species in Xiaohuangshan of Nanling National Nature Reserve, Guangdong Province of southern China.
Method We set standard community plots along the elevation gradient. The competition index of P. kwangtungensis was calculated by Hegyi individual competitive indices (CI) model. The function model between DBH, the competitive index of stand, and interspecific competition were established by regression method.
Result (1) There was a significant power function relationship between DBH and tree height. (2) Intraspecific and interspecific competition intensities of P. kwangtungensis were 893.736 and 559.682, respectively. (3) There were many associated species of P. kwangtungensis, and the order of main interspecific competition species was Schima superba > Castanopsis eyrei > Pentaphylax euryoidex > Pinus massoniana > Tsuga longibracteata > Delonix regia > Fokienia hodginsii > Exbucklandia populnea. (4) There was a significantly negative correlation between the competition index with the stand, accompanying species, and the DBH of the objective trees.
Conclusion Intraspecific competition was dominant in the community. The competition intensity of P. kwangtungensis decreases inversely with the growth of DBH. When the DBH of P. kwangtungensis reached 30 cm, the competition intensity declined stably, and the relationship between the forest stand competition intensity and DBH of the target trees is conformed to power function. This model can effectively predict the intraspecific and interspecific competitions of P. kwangtungensis.