It was found after 5 years,the reserved tree density of 1 275 trees/hm 2 for the first and 525 trees/hm 2 for the second would significantly hasten the diameter and standing volume growth ,improve the stand structure,and effectively shorten the rotation age.

GMG/Y was markedly affected by narrow-sense heritability, additive variance at mature age, rotation age, plant-dependent cost, total budget and the time needed to produce the test plants, while diversity loss and recombination cost had rather weak effect on GMG/Y.

According to the practice and management of short regulatory rotation age in larch plantation, this paper states its necessity and technique key points.

selecting fastgrowing hybrids, adopting rational spacing and rotation age are the basic measures to increase biomass and guarantee both wood quality and good economic benefits.

According to the maximum mean annual increment,the rotation age should be 38.Considering the small and middle wood used as mining timbers,posts and in housing construction in the country,the rotation age should be 20~25.According to the cost and income,the financial rotation age should be 25~ 35.In conclusion,according to the different purposes the general rotation age should be 26~30.

We show that even in the deterministic case if the current interest rate deviates from its long-run steady state, interest rate variability may change the rotation age significantly when compared with the constant discounting case.

Larch Hills and Inonoaklin River were the two superior provenances with an expected gain of 13% and 10% in stem volume at rotation age of 60?years in TOLO.

In both cases the average rotation age is approximately 14 years.

The optimum biological selection age, the selection age where average annual gain is maximised, was four years for an assumed rotation age of 15 years.

An appropriate rotation age for sawn-timber production was found to be 8-9?years old, at which the mean annual increment of sawn timber would be maximized.

This paper discussed the optimum selection ages(xmax) of height, diameter and volume in 1-69 poplar x Simon poplar and 1-69 poplar x Nigra poplar F1 clones, using annual genetic gain(△Gt) and expected genetic gain(Gt) as the evaluation criteria, and the stability of their early selection result was tested. Age of early selection might be as ealy as 2 years after plantation(not including plantation age) in 1-69 poplar x Simon poplar Ft clones. Age of early selection was 3~4 years after...

This paper discussed the optimum selection ages(xmax) of height, diameter and volume in 1-69 poplar x Simon poplar and 1-69 poplar x Nigra poplar F1 clones, using annual genetic gain(△Gt) and expected genetic gain(Gt) as the evaluation criteria, and the stability of their early selection result was tested. Age of early selection might be as ealy as 2 years after plantation(not including plantation age) in 1-69 poplar x Simon poplar Ft clones. Age of early selection was 3~4 years after plantation(including plantation age) in 1-69 poplar x Nigra poplar F, clones. Selection for these two F1 clones at these ages would represent that at rotation ages, and genetic gain of the selection would achieve the maximum value. Therefore, it was concluded that early selection would be effective.

A series of methods for long-term timber forest planning and investment decision making are provided in this paper. Based on market forecasting, an objective model is established to achieve optimal equal-annual-payment and lower access cost. Various factors such as regional location, site class, management intensity and timber assortment are taken into consideration. By derterming comprehensive economic evaluatuon coefficients in various conditions, the objective investment scale and reson-avle allocation can...

A series of methods for long-term timber forest planning and investment decision making are provided in this paper. Based on market forecasting, an objective model is established to achieve optimal equal-annual-payment and lower access cost. Various factors such as regional location, site class, management intensity and timber assortment are taken into consideration. By derterming comprehensive economic evaluatuon coefficients in various conditions, the objective investment scale and reson-avle allocation can be reached. The economic rotation age is caculated. By using a dynamic model, many relations such as planning and decision making, long-term and shart-term objectives, forest resources, reforestation, timber production and social demand are all properly handled. A quantative method for analysing capital supply is introduced so that production structure, ownership, location and project evaluation are all linked together.

By surveying the biomass, determining the wood property and examining the economic benefits of plantations of poplar hgbrids P-15A, 1-24 and Sacrau, it was found suitable that short-rotation culture of poplats is used to produce pulpwood in the region where we made the investigation. selecting fastgrowing hybrids, adopting rational spacing and rotation age are the basic measures to increase biomass and guarantee both wood quality and good economic benefits.