THE METHODS AND STANDARDS OF SELECTING EXCELLENT NATURAL FOREST STAND OF PINUS YUNN AN ENSIS IN CENTRAL YUNNAN

In this article, quick-growing and abundant harvesting stand was appraised by the mean annual height of its tree-classes Ⅰ-Ⅲ, and its economic value of wood was appraised through the slope of grain. After investigating the environment factors and turning them into quantity, the authors inputted the datums into computer for the approximation of annual increment and slope of grain so that the theoretical value of stand heritability was calculated, and a sythetic formula for predicting the theoretical value of the mean annual height increment and slope of grain was set up on the basis of the datums from the computer. The quality of stand was evaluated by means of the selection index of mean annual increment and slope of grain. Based upon the value above average, the standard error(0.5) was added and then the standard for excellent forest stand of Pinus yunnanensis in the middle part of Yunnan was formed. By conducting feedbaok with the standard, the excellent stands were selected and transformed into the seed stands of mother trees. The selected proportion is 23.1% which is enough to meet the needs of seed collecting and use in production.