Chinese fir: related expressions between diameter breast-high and crown width and their application.

Key words: 
• Chinese fir (Cunninghamia lanceolata ) /
• provenance /
• density o f management /
• crown overlappable coefficient /
• regression analysis

Abstract: There are 19 provenances in the Chinese fir forests of proenance test made by Forestry Research Institute of Long' quan City , Zhejiang Province. The measurement and analysis of 14 years old stands show that relationship between DBH ( x ) and crown width ( y ) is closely and can express it with y= axb . According to the statistical tests, 19 provenances can divide into 3 groups of the south subtropics, the middle subtropics and the north subtropics.The density targets of management and crown overlappable coefficient sobtained respectively can make reference use of thinning for Chinese fir forests all the country.