A New Single-tree Competition Measure── Relative Effective Crown ratio

ln this paper,a new singletree competition measure──Relative Effective Crown Ratio(RECR),which is independent of distance,is put forward,based on the sunnedeffective crown and the relationship between the sunned effective crown diameter and the DBH of trees in Larix principis-rupprechii stands of different densities in Saihanba Forest Farm,Heibei Province.This measure,which is the ratio of the sunned effective crown diameter of the tree in the stand to that of the open-grown tree with the same DBH,mav be usedin many aspects in even-aged stands,such as the stand growth dynamic prognosis,stand density control and management etc.