Variable Growth Intercept Models And Stand Dominate Height Growth Process For Chinese Pine (Pinus Tabulaeformis) Natural Forest In The Guandishan Forest Region

Site index is an important tool in forest management and planning. Growth intercept models and tables are effective tools for estimating site index, particularly in obtaining an accurate site index for juvenile stands. The growth intercept allows site index to be accurately estimated for young stands. Stem analysis and ecological data were collected from 29 plots in the guandi mountain forest region. Two or three site trees were stem analyzed from each plot, the data were converted into top height-breast height age, growth intercept, years to breast height and site index data. A site index, growth intercept, years to breast height, site index curves and site index predications model were then fit to the data for pinus natural. After analysis to the regressions, draws the conclusions as follows: the year to breast height was negatively related to site quality in general with small differences between different site indexes, the result supports the use of breast height age site index models instead of total age models because the breast height age models avoid the early erratic growth below breast height; Good relation between the growth intercept and site index, the relation increase as breast height age increase; the relation decrease as the site index age increase at the same breast height age, but none of the growth intercept models showed evidence of significant intrinsic or parameter-effects nonlinearity or parameter bias, the variable growth intercept models have good precision, they can estimate pinus natural site index from average the first 3-35 years of height growth above breast height of a stand. After the compromise between the variable growth intercept models and site index prediction, we have the conclusion that the variable growth intercept models have more precision, especial for young stands than site index prediction.