Growth Analysis of Loblolly Pine in Hilly Area of Zhejiang and Eastern Anhui Province

According to the data of 31 sample plots and 19 analytical trees of loblolly pine in Eastern Anhui and Northwest and Southeast of Zhejiang Province,it shows that the site index of the area,where the loblolly pines are distributed is 10～24 in general,mostly 14～18.In the region of site index 20～24,the interlock point of the average yearly growth of height and the successive yearly growth is at the age of 8 for the tree height and at the age of 10 for the DBH; while in the region of site index 14～18,they are at the age of 12 and 10 respectively;while in the region of site index 10～12,the interlock point for DBH is postponed to the age of 16.In the regions of above mentioned three site indexes,the successive yearly growth of volume and the average growth of volume doesn't meet at the age of 20.Another analysis shows that the correlation coefficient for the density and diameter is r=0.652 87·;while for the diameter with bark 0.368 4+1.074 850x(x is the diameter without bark).In the investigated area,the form-factor of the loblolly pine is 0.58 at the age of 10;0.54 at the age of 15; 0.49 at the age of 20.The regression equation for crown width and diameter Y=0.88+0.188 9x(x is DBH),which has a significant correlation.The heightdiameter ratio of this tree species changes with the change of region and cultivation density,when it is at the age of 15～20,the regression equation for density(trees/hm2)and DBH Y=46.32+0.096 4x(x is density).The suitable cultivation density is 1 800 trees/hm2.