关键词：
净现值;内部收益率;立地条件;连作;经济风险;生态风险
摘 要：
以广西桉树林为研究对象,运用净现值、内部收益率两种经济指标探索不同立地条件及连作代数对桉树林经济生态效益、价格盈利概率的影响。结果表明:林地立地指数大于17时,桉树林在一般市场条件下都可获得收益;当桉树木材市场价格为560.66～1 661.00元/m~3时,处于立地指数差的桉树林的盈利概率为0.14%且固碳效益降低,经济及生态抗风险能力差;在立地指数等于21的基础上进行桉树连作,第四代桉树林经济效益明显降低,当桉树林木材市场价格低于837.90元/m~3时,经营第四代桉树林在经济上易亏损且碳汇效益低于中等立地的效益产出,生态风险高。由此,建议当桉树连作至第四代或林业用地立地条件差时应及时更换树种、种植水土保持较好的乡土树种从而恢复地力以减少经济损失。
译 名：
Ecological and Economic Risk Assessment of Eucalyptus
作 者：
WANG Tingran;QIN Xiaorui;LU Fadian;Forestry College,Shandong Agricultural University;
关键词：
net present value;;internal rate of return;;site condition;;continuous cropping;;economic risk;;ecological risk
摘 要：
(1)Background——Eucalyptus has become an important fast-growing broad-leaved timber species in Southwest China.However,there are some problems in Eucalyptus plantation,such as continuous cropping effect,decrease of forest biodiversity,soil erosion and water consumption,which have become the research focus at home and abroad.(2) Methods——Taking the Eucalyptus plantation in Guangxi as the research object,based on the eucalyptus tree height,DBH,age,stand density and other data of the 533 Eucalyptus plantation standard plots laid out by the First-class inventory of Guangxi in 2015,and input and output data of forestry management of 8-year Eucalyptus plantation production conducting field surveys in Guangxi Gaofeng Forest Farm,using dynamic analysis to analyze the price sensitivity and profit and loss threshold of Eucalyptus plantation,and explore the effects of different site conditions and continuous cropping conditions on the economic benefits,ecological benefits,and price profitability of Eucalyptus plantation.(3) Results——①The forest land with site index(SI≥17)can obtain income under general market conditions.When the net present value and internal rate of return about site index difference(SI=13)are negative,and after sensitivity analysis,the price fluctuation of Eucalyptus cannot reach the price of eucalyptus required by the social average rate of return,which indicates that the opportunity cost of planting eucalyptus is low,so it is suitable for other investments.Furthermore,when the market price of Eucalyptus is 561-1661 yuan/m~3,the profit probability of internal rate of return is 0.14%.And when the site index is 13,and the carbon sequestration benefit is reduced.②On the basis of SI=21,the thresholds of net present value and internal rate of return of the fourth generation are increasing,especially in the fourth generation.However,the return of net present value is negative and the threshold of social average rate of return reached is higher than the current price.For the third generation,the site conditions continue to decline,close to the medium level,and the ecological benefits keep down.For the fourth generation,the site conditions continued to deteriorate,and the ecological benefits also decreased.Therefore,it is not suitable to continue to plant the fourth generation eucalyptus,and other native species can be considered to improve the existing ecological situation.When the market price is lower than 837.901 yuan/m~3,the fourth generation is easy to lose money and the carbon sink benefit is lower than the benefit output of the medium site,so the ecological risk is high.(4) Conclusions and Discussions——The economic and ecological benefits of 8-year-old eucalyptus forest under different site conditions are different.For the eucalyptus forest with poor site conditions,from the analysis of economic benefits or price sensitivity,the profit probability is very small.After accounting the carbon sink benefit,the ecological benefits are higher than the economic benefits,and the economic benefits of planting eucalyptus are not good.In addition,after continuous cropping of eucalyptus on the basis of SI=21,the economic and ecological benefits of the fourth generation of eucalyptus are calculated.And the level of economic benefits is low,while the ecological benefits are far less than those of medium site conditions.But the profit probability decreases with the increase of continuous cropping algebra.Therefore,it is suggested that when eucalyptus is planted to the fourth generation or the site conditions are poor,the tree species should be replaced in time,and the native broad-leaved tree species should be constructed,so as to constantly restore the land capacity to reduce economic losses.
