Studies On Crown And Understory Vegetation Of Pinus Tabulaeformis Plantation In Beijing Area Based On Forest Vegetation Simulator (FVS)

Seventh National Forest Resources Inventory showed that the national forest coverage rate reached 20.36 percent, compared with the sixth inventory, plantation area of net 8,431,100 hm2, plantation area ranks first in the world. With the continuous expansion of plantation areas, plantations on China's ecological environment and economic development play an important role, but because of extensive long-term management of the traditional way of making low quality of our plantations, poor ecological functions. Pinus tabulaeformis were important afforesting tree species in Beijing mountain area, an area of 79,468hm2. Its plantation area was 61,000 hm2 and accounted for about 77%and had a series of ubiquitous problems, such as density too much, trees grow too slowly and poor stand quality and so on. This first attempted to apply the U.S. Forest Resource Inventory System (FIA) in the canopy survey, conducted in Pinus tabulaeformis's canopy survey. Through plots investigations and mathematical modeling, analyzed relations between tree growth and crown growth, established crown model, relations between crown and understory vegetation diversity index, relations between crown and forest biomass, forecasting stand dynamics growth of under different management measures which were studied by plots investigated math modeling,and then forecasting crown growth and the growth of understory vegetation. The main research results were as follows:1. Pinus tabulaeformis plantation (40～50a) stand density was an important factor which influenced the changes of the crown factors. Stand density should be controlled about the 1500T·hm-2, this was conductive to the healthy growth of crown, and would be also beneficial to the tree growth.2. The relations were established between crown-fullness ratio and tree growth factors by regression analysis. Model fitting results were as follws: DBH=29.248e1478Rc;H=13.58 e-1.121Rc; V=0.3715 e-3.308Rc. The examination results indicated that:these models had good fitting and expected effect.3. According to the branch analysis of the results, established the power function between the biomass and crown diameter:WC=0.4087DBH2.21; the examination result indicated that it had good fitting and expected effect.4. Quadratic model was the best fitting result through using 4 kinds of crown models of FVS, the result was CW=-0.7133+0.3714xDBH-0.0037×DBH2 R2=0.6959; the examination result indicated that it had good fitting and expected effect, and forecasting accuracy was higher than prievous model.5. Established the relations of regression curve between crown and Shannon-Wiener index H', the exponential function was the best fitting result which was H'=1.232eo0.0912CW R2=0.7699; this model had good fitting and expected effect.6. Cubic models were drawn up to match the relations between crown and understory herbaceous biomass, shrub biomass. These models separate were: W草=244.192-117.488×CW+60.196×CW2-6.015×CW3; W(?)=2.559×103-1.494×103×CW+716.935×CW2-74.763×CW3; These examination results indicated that these models had good fitting and expected effect. 7. Typical stand dynamics growth for the natural growth and the effect of management measures (the lower and the upper thinning) for Pinus tabulaeformis had been visual forecasted, and the growth of crown and understory vegetation could be forecasted. It was a reasonable prediction. Pinus tabulaeformis plantation in this study could provide reference for the scientific management and this study method could also broaden the scope of application of the system provides a reference scale.