Spatial Distribution and Seasonal Changes of Needle-leaf Area Density within 17-year-old Chinese Fir Crown

The vertical,horizontal and two dimensional distribution of needle leaf area density (NAD) within 17 year old Chinese fir (Cunninghamia lanceolata) crown and their seasonal changes were surveyed andmodelled in Fenyi County of Jiangxi Province.It showed that themean total needle leaf area (NA) and NAD within a single crown were 25.42m2 and 2.2727m2·m-3 respectively in themidmay,but the older the needle leaf,the greater the NA and NAD.The horizontal and vertical NAD distributions could be well fitted by β function and the two dimennsional NAD distribution by the trend surface equation of relative crown height and relative crown radius.ThemaximumNAD was occurred at themid front section of branches ofmid upper crown;however the current needle leaf was locatedmainly in the upper and outer crown while old needle leafmoved toward themid lower andmid inner crown.With the increase of tree age,accumulated needle leaf area index decreased and the vertical distribution of needle leaf area centered toward upper crown.The seasonal variation of biomass dry weight and area of current needle leaf followed Logistic equation.At the end of growing season,themean total NA and NAD within a single crown were up to 29.4243m2 and 2.6307m2·m-3 respectively.