Study On Models Of 107-poplar Growth And The Maturity Age In Shandong Province

As all known, Shandong is one of the largest provinces for poplar plantation. Although the analysis and evaluation of poplar growth with yield has made some development, systematical research related poplar mensuration has not been completed, especially in poplar yield models and estimation. In this paper, based on the 107-poplar plantation in Shandong province, by statistical analysis of the SAS software for operation platform, discussed the research methods of 107-poplar growth forecast, determined the felling age, established the polymorphic site index table and the basal area growth model.The main research content and summary are as follows:1. According to Richards function, several models were imitated for estimating poplar based on poplar temporary and fixed standard stands in Ning yang Shandong. The growth of the poplar plantations presented an"s-shaped"curve, and high accuracy was exhibited by the growth prediction model when it was used to imitate the growth of breast diameter, height and volume of the trees, P<0.0001; Using some data of poplar plantation that are not used for building models to test, the result showed that the measured values and simulated values had no significant difference (p>0.05). Therefore, the models may be applied to predict the growth of 107-poplar and provide basis in artificial forest reasonable management.2. The maturity age of poplar was systematically studied in Ning yang Shandong province. The quantitative maturity age was determined by the largest growth of average accumulation; The technical maturity age was calculated by the standard of timber assortment; By means of discounted measure, economic analysis was analysised and economic maturity was determined by the maximum net present value. According to"the felling age was proposed on the basis of the technical maturity with a emphasized considering of economic maturity and an appropriate considering of quantitative maturity", the felling age of poplar should be 11¹3years for good sit condition and 9¹1years for medium and bad site condition .Besides, to analysis the sensitivity of timber price, afforest cost and interest rates on many levels, and on this basis, to explore risks and uncertainties and the corresponding managerial decision-making when constructing the fast-growing poplar.3. The site index curve established in the paper has really described the processes of poplar growth. The stand height (H) tends to the stable value while the stand age is not younger. Mean time the height growth of young stand shows much faster in high site condition, but decreased faster in old age. On the opposition, the height of young stand grows slowly in lower site condition, and also decreased slowly in old age, which keep a tally with that poplar height grows fast in earlier period. The results by tested also shows that Richards model with 4 parameters fitted poplar site has been considered feasible.The Richards model with 4 parameters is:H = SI/((1-e^{-6(b0+b1×SI)}))^b2+b3×SI(1-e^{-A(b0+b1×SI)})^b2+b3×SIWhere H= mean height of dominating trees, SI= site index, bi = parameters, i from 0 to 3.4. Site condition, year and density are the main factors affecting the growth of stand. The model is established by using Richards the theoretical equation as the basic model, and introducing the site index, density and shelterbelt age to the model. The establishment of the model helps to predict the volume growth in study area. The results by tested also shows that Richards model with 5 parameters has been considered feasible.The Richards model with 5 parameters is:G = = c₁*SI^c₂ (1-exp(-c₄*SDI^c₅(t-t₀)))^c ₃Where G=basal area, SI= site index, SDI= density index, c i= parameters ,i from 1 to 5.