Study On Growth Potential Of Natural Evergreen Broad-leaved Forests

Based on the data of fixed sample plots of continuous survey and typical sample plots and method of stem analysis, evaluation of site quality, stand structure, growth law, biomass and regeneration measure about natural evergreen broad-leaved forest were studied in Yan ping district of Nan ping city, Fujian province. The main results were the following.1.The main site factors were surveyed and analyzed, which affect growth of natural evergreen broad-leaved forest, at the same time Principal component analysis and Quantitation theory I were used to determine the leading factors. The results showed that slope site, altitude, slope direction, slope grade were leading factors which affect trees growth. The favorable evaluation models of productive force were put forward. The evaluation level to site was raised from qualitative description to quantitative evaluation.2. Four probability distribution laws were applied to analyze diameter-distribution of natural evergreen broad-leaved forests of 50 sample plots. Compared with the results of the five probability distribution laws , the diameter-distributions of the natural broad-leaved forests obey mainly beta distribution and gamma distribution. The resulting principle will provide an important guide for prediction of tree numbers and volume of various diameter grades and volume of selection cutting.3. Based on stem analysis of mean tree of typical sample plots, the regression models between DBH, tree height, tree volume and age were fitted. The results showed as follows. D=-1.16853+0.27466A-0.00080A²+0.00001A³ r=0.99710 H=-0.27665+0.24984A+0.00025A²-0.00002A³ r=0.99790 (applacation range:6≤A≤68) V=0.00167-0.00055A+0.00003A² r=0.989704. The regression models between DBH and tree volume, between tree height and tree volume showed as follows. V=1.2863×D^0.777136 r=0.8775 V=1.7537+0.9424H-0.0195H² r=0.8229 (applacation range:5≤H≤24) The regression models between DBH, tree height and tree volume showed as follows.V=1.7525+0.4137D+0.2235H r=0.8974 The regression models between moisture content (%) and height as follows.Y=41.7347+0.3108X+0.0117X² r=0.90815. Eighteen typical sample plots (16m×16m) were established for investigating the number of young trees and seedlings. Each sample plot was divided into sixteen small sample plots (4m×4m). These results showed that: there were young trees and seedlings in each sample plot and the distribution pattern of Cyclobalanopsis chungii population is clump.As a whole, the natural forest renewal ability is nice in the area and the strength of manual intervention should be down.