The Effects Of Stand Density On Cone Yield And Establishment Of Period Cone Yield Model For Korean Pine Plantation

The data were collected in 15 permanent sample plots and 6 temporary sample plots of a 41 years old Pinus koraiensis plantation in Meng Jiagang Forest Farm, Jiamusi City, Heilongjiang Province, including tree growth and cone yield in lean year, mean year, mast year, and total fruiting period. Stand density effects on tree growth and cone production and the relationship between cone yield and tree and stand growth indexes were analyzed at first, then, the non linear regression model for predicting cone yield of individual trees and stand of Korean pine plantation were established. The results showed that:(1) Stand density had significant effect on mast year cone yield and period cone yield (P<0.05) but not off year and mean year cone yields (P>0.05). Mean year and mast year cone setting rate were significant influenced by stand density (P<0.05) but off year and period cone setting rate were not significant (P>0.05). Stand density (800～1000)/hm2 showed the highest in stand volume (22.6728 m3) and highest period cone yield (1276 cones) of Korean pine stand, indicating that it was the most suitable stand density for Korean pine cone and wood production simultaneously.(2) The mast year cone yield was significant influenced period cone yield (P<0.05) but not off year and average year cone yields(P>0.05). (off year+mean year) cone yields was significant influenced period cone yield(P<0.05). Off year, mean year and mast year cone yields accupied 6.04%,19.89% and 74.07% of mast cone yield respectively, the maximum proportions were 11.55%(stand density 560 trees/hm2) and 34.99%(stand density 370 trees/hm2) respectively for off year and mean year. Off year plus mean year cone yields accupied 25.93% of period cone yields and had significantly positive correlation with period cone yields, indicating that off year plus mean year cone yield was an essential part of Korean pine cone yield and should be considerate in establishment of prediction model for cone yield of Pinus koraiensis.(3) According to the relationship between the period cone yield and tree growth indexes (tree height, diameter at breast height and crown width), the non linear regression models for predicting the period cone yields of Korean pine trees were established. Through comparision the fitting and testing results of each model, the optimal model (3-1) y=a*(D*CW)b was determined, the relative difference, absolute value of the relative difference and prediction accuracy were-0.631,0.854 and 88.14% respectively.(4) According to the relationship between the period cone yield and stand growth indexes including stand density, mean tree height, mean diameter at breast height and crown width, the non linear regression models for predicting the period cone yields of Korean pine stand were established. the optimal model (3-10) y=a*(Db)*(SDc) was determined according to the best fitting performance, the relative coefficient, relative difference, absolute value of the relative difference and prediction accuracy were 0.568,0.002,0.09554 and 87.53% respectively.