| 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, regeneration measure, and selection cutting about natural evergreen broad-leaved forest were studied in Yanping district of Nanping 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, sort of soil 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. Five probability distribution laws were applied to analyze diameter-distribution of natural evergreen broad-leaved forests of 77 sample plots. Compared with the results of the five probability distribution laws,the diameter-distributions of the natural broad-leaved forests obey mainly gamma distribution. The resulting principle will provide an important guide for prediction of tree numbers and volume of various diameter grade and volume of selection cutting . 3. The formula of peak width at half height (PWH) and the maximum density model were used to study the reasonable density about various layers of natural evergreen broad-leaved forests. The results showed there are remarkable regression relationships between mean DBH and density, between mean area of crown and mean DBH. The reasonable densities about various layers showed as follows. The first layer 0.762N1max~1.197N1max,N1max= -287.11+18874.36/D1 r=0.91 the second 0.399N2max~1.558N2max,N2max= -68.08+5770.23/D2 r=0.82 the third 0.824N3max~1.159N3max,N3max= -68.11+4239.67/D3 r=0.96 The density can tend to lower limit when management objective is cultivating big size tree, otherwise ,the density can tend to upper limit. The density of sun trees can be small, and that of shade-resistant trees can be bigger. 4. 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= -0.4186+0.3566 A+0.0386 A2-0.0009 A3 r=0.8688 H= 0.9826+0.3708 A+0.0269 A2-0.0007 A3 r=0.9407 V= 0.0058-0.0029 A+0.0004 A2 r=0.8637 5. The regression models between DBH and tree volume, between tree height and tree volume showed as follows. V= 84.31436-86.91317×0.989556D r= -0.8338 V= 30.68519-35.54688×0.9573753H r= -0.8223 The regression models between DBH, tree height and tree volume showed as follows. V= -3.3204+0.4883 D+0.5102 H r=0.8765 The regression models between moisture content(%) and height at stem of Castanopsis fissa showed as follows. Y= 49.11607+0.722199×1.185886X r=0.9916 6. 11 typical sample plots(20m×20m) were established for investigating the number of young trees and seedlings. Each sample plot was divided into 25 small sample plots(4m×4m). In 7 sample plot(63.64%), there were young trees and seedlings in more than 23 small sample plots. 2 sample plots were cut selectively, two years later the numbers of small sample plots in which young trees and seedlings existed rise to 24 and 22 from 11, respectively. These results showed natural evergreen broad-leaved forest have strong regeneration force and young trees and seedlings distribute evenly. As long as suitable nurture measures are applied, the forest can renew in short time after selection cutting. 7. According to the present situation of natural evergreen broad-leaved forest and its management, and combining data of sample plots, the author analyzed problems existing in present selection cutting. Based on experiment of selection cutting, rational ratio of selection cutting was put forward. Furthermore, rational countermeasures about selection cutting were put forward.
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