The Study Of Stand Spatial Structure And Pine Nut Yields For Fruit And Wood Dual-used Korean Pine Forests

Based on data of the branch analysis of 70 sample trees from 12 sample plots (area 0.06 hm2) and stand pine nut yields (2008-2010) from 21 permanent sample plots (area 0.10 hm2), the optimization management method of spatial structure for fruit and wood dual-used stands was researched for Korean pine (Pinus koraiensis) plantation in Mengjiagang forest farm, Jiamusi, Heilongjiang Province. Firstly, based on the allometric growth equation, the predicting models of crown volume (CV) and crown surface area (CA) were developed, and correlations between pine nut yields of a bad harvest year, an average harvest year, and a good harvest year with crown sizes were analyzed for Korean pine. Secondly, the stand competitive indexes were investigated, including simple competition index, growth space index and growth space competition index. In addition, the size of reference tree in structure unit and average situation of stand neighborhood comparison were studied based on the neighborhood comparisons of diameter at breath height, total height, crown length and crown width of trees, and neighborhood pattern was used to analyze the spatial structure relations. Finally, the procedure how to select the intermediate cutting trees when optimizing spatial structure of stand was illustrated by using No.4 sample plot as example.In order to predicting nut yield of Korean pine, crown volume and crown surface area models were developed using diameter at breast height and crown length as independent variables and the determination coefficients (R2) of the models were all above 0.55, and prediction accuracies were above 85%. The models were applied to analyze their influence on the pine nut yield. The result indicated that the pine nut yield was linear correlated with crown volume and crown surface area for Korean pine plantation, in which the relationship between pine nut yield in a good harvest year with crown volume and crown surface area was the most obvious (r=0.7267-0.7338), followed by an average harvest year (r=0.6888-0.6675), the worst was a bad harvest year (r<0.5). The competition situation of single tree with adjacent tree was concerned. The descriptions of the three kinds of competition index for Korean pine had a strong consistency. Considering the status of growth dominance for reference tree and adjacent tree, the change of each tree variable had a big difference, but diameter at breast height and crown length had a highly consistency. The horizontal distribution patterns of Korean pine plantation are uniform, random, and aggregated distribution, but most is uniform distribution.Because the combined influence from its internal and external factors, analysis of pine nut yield for individual tree of Korean pine was difficult to have a conclusion with high accuracy. At stand level, average nut yield of each tree in Korean pine stand could be improved though increasing the average crown size of tree, which could be achieved by forest thinning. In thinning process, trees with smaller growth space index, growth space competition index, and supressed in the competition should priority to be considered as cutting trees. In addition, make sure that the spatial distribution pattern of Korean pine plantation tended to uniform distribution after thinning. Therefore, stand structure of fruit and wood dual-used Korean pine forest after thinning will be more reasonable for improving timber quality and pine nut yield and reaching fruit and wood dual-harvested purpose. The results will provide a foundation for optimizing management of Fruit and Wood Dual-used stand for Korean pine plantation.