Stand density is referred to as the number of trees standing in the process of tree growth on a unit area

which closely related to forest growing conditions

stability

forest yield

quality and other factors.Based on a survey on Larix principis plantations with various densities in State-owned Forest Bureau of Mulan in Hebei Province

the study proposed a competition index of crown width by adopting the Hegyi model

which uses a single wood competition index model to calculate the competition index.By fitting crown width

stem diameter at chest height and relative crown width competition index

the management density was found varying in response accordingly to the diameter

given a competition level.T he management densities of Larix principis plantation were calculated for the competition indices of 0.2

0.4

0.6

and 0.8

respectively.