【作者】 李子敬；

【导师】 张守攻；

【作者基本信息】 中国林业科学研究院 ， 森林培育， 2011， 博士

【摘要】 日本落叶松(Larix kaempferi)是北亚热带地区重要的引种栽培树种,目前该区域的栽培面积已超过33.3万公顷。北亚热带中山山地是我国日本落叶松最适宜引种区,在该地区,日本落叶松表现出早期速生、适应性强、材质优良、不与农业争地、抗冰雪及病虫等自然灾害能力强等特性。日本落叶松是优良的造纸原料,相比其他种类落叶松而言,其生物质产量和纸浆得率最高,卡伯值较低,纤维最长,打浆能耗低,制浆造纸工艺易于控制,成纸性能稳定,最具造纸原料应用潜力。作为短周期纸浆用材树种,日本落叶松对实现林纸一体化有着广阔的市场前景。但由于该区日本落叶松引种时间较短,对纸浆材的轮伐收获周期尚未进行针对性的研究,因此如何科学合理的采伐利用成为当前日本落叶松培育中亟待解决的问题,因此本研究通过对日本落叶松各种成熟龄的探讨,开展了日本落叶松最佳轮伐期的研究,以期为北亚热带日本落叶松的生长经营提供经营指导。主要研究方法和结论如下:通过生长模型法和多元非线性回归的方法研究了北亚热带日本落叶松的数量成熟龄,最终优选出Schumacher修正模型建立的蓄积量生长方程,求算出不同立地质量和林分密度的日本落叶松的数量成熟龄为28-42a,林分密度越大,立地指数越高,则数量成熟龄越大。通过测定北亚热带日本落叶松不同年龄植株的制浆造纸特性、纤维特性和纸浆物理强度,在对比不同指标间随年龄变化趋势和差异的基础上,综合判断得出了北亚热带日本落叶松的制浆工艺成熟龄为13-22a。同时,利用方差分析的方法对不同立地质量、不同林分密度的日本落叶松和不同树体部位(上部、中部、下部树干和枝)的制浆性能进行了分析,得出结论为立地质量和林分密度对日本落叶松制浆造纸性能无显著影响,不同部位树干间差异也不显著,但树干造纸性能均显著优于枝。在讨论适用于林业经济分析的合理贴现率的基础上,通过改进后的DCF方法(折现金流)分析方法(土地期望值法LEV、年均净现值法ANPV和内部收益率法IRR)和目前较为先进的实物期权法(Real Options)分析技术,探讨了日本落叶松纸浆林的经济成熟龄。得出的结论为立地指数为13、15、17、19和21的日本落叶松林分的LEV成熟龄分别为25-26a、24-26a、22-24a、20-23a、20-21a;ANPV成熟龄分别为24a、23-24a、21-22a、18-21a、18-19a; IRR经济成熟龄分别为26-27a、24-26a、21-24a、18-22a、17-19a;在当前价格水平下,五种立地指数的实物期权经济成熟龄分别为25-27a、24-26a、22-23a、21-22a、19-22a。分析结果还表明,立地质量越高或林分密度(合理范围内)越高,则经济成熟龄越小,经济收益越高。对不同立地质量和林分密度的日本落叶松林分价格、贴现率和营林成本在假设水平下的变化基础上的经济收益变化进行了敏感性分析。结果表明,纸浆材价格的降低、营林成本和贴现率的上升,均使得日本落叶松纸浆林的经济收益减小;最显著影响因素是贴现率,其次是纸浆材价格及营林成本。通过实物期权法分析日本落叶松纸浆林的经济成熟龄,得出了不同林龄的各种日本落叶松林分的采伐价格阈值(Harvest price thresholds)和最短轮伐期。采伐价格阈值的涵义是某一林龄的林分实施采伐的纸浆材最低价格,即当某一林龄的日本落叶松林分大于该林龄对应的价格阈值时应选择采伐策略,而小于此阈值则应选择等待策略。最短轮伐期的涵义是在纸浆材价格较高时不同日本落叶松林分的最短采伐林龄,而在低于此林龄时,无论纸浆材价格为何值均应选择等待策略(即推迟采伐)。结果显示,日本落叶松纸浆林的采伐价格阈值均随林龄的增大而减小,且随立地指数的增加和林分密度的增加而减小。最短轮伐期具有随林分密度的增加而减小的趋势,五种立地指数(13、15、17、19和21)的日本落叶松纸浆林的在较高价格情形下的最短轮伐期分别为22-25a、21-23a、19-21a和17a。依据层次分析法和日本落叶松纸浆林轮伐期确定要素,遵循“以工艺成熟为基础,重点考虑经济成熟,兼顾数量成熟”的理念,构建了日本落叶松纸浆林最佳轮伐期的综合决策体系,确定了不同成熟龄的评价权重。通过综合决策体系各指标的权重,得出不同立地指数的日本落叶松的最佳综合轮伐期为:立地指数为13和15的日本落叶松林分的最佳综合轮伐期为18-19a;而立地指数为17、19和21的日本落叶松林分为17-18a。最佳轮伐期问题是一个多准则的综合决策的复杂问题,需要综合各种成熟评价指标进行综合判断。森林的经济成熟是国外许多学者研究森林的最佳轮伐期所重点讨论的问题,我国拥有着丰富的用材林资源,随着我国市场化进程的不断加快和木材需求的不断增加,从经济成熟角度来探讨最佳轮伐期将是众多国内学者研究的热点和重点。在本研究中着重讨论的实物期权法,充分考虑了日本落叶松经营过程中的价格变化风险和人的管理柔性价值,为日本落叶松的市场化经营提供了稳健且灵活的经营策略,是评价森林经济成熟的更为科学的方法。综上所述,本研究论述的各种日本落叶松成熟龄及综合决策最佳轮伐期,为北亚热带日本落叶松栽培区域的生产和经营提供了解决日本落叶松森林资源经营和利用的指导性方法和理论依据。更多还原

【Abstract】 Larix kaempferi is one of important tree species in north sub-tropical area in China, where is the most appreciate area for L. kaempferi cultivation and in which it had been planted over 0.33 million ha. In this area, L. kaempferi grows fast at early ages and usually has better wood properties, and never occupies lands for agriculture with better acclimation ability and anti-disaster ability. Moreover, it had been proved that L. kaempferi is one kind of good pulping material compared with other kind of Larix because of its higher biomass yield and pulping yield, longest fiber, lowest kappa number and pulp beating energy consumption, easier controlled pulping procedure , stable properties of paper and the potential for paper-making. Therefore, L. kaempferi has broadly market prospects and it is significant to forest-pulp-paper integration as a species to short-rotation and pulping-making. However, due to relatively short introdction period of L. kaempferi in this area, the rotation problem of has not been researched. Consequently, how to harvest L. kaempferi scientifically has become a significant problem in L. kaempferi plantation management. Therefore, this paper studied the optimal rotation age of L. kaempferi by discussion of various maturity ages in order to guiding management and production in this area.The main methods and conclusion are:The Quantitative Maturity Age for L. kaempferi was studied by Growth Model method and non-linear regression technology. The results showed that Extended-Schumacher model was perfect to describe the stand stocks growth for L. kaempferi. The Quantitative Maturity Age of L. kaempferi in various site index and stand density ranged from 28-42a, and the stand with higher site index and stand density usually had older Quantitative Maturity Age.The Technology Maturity Age for L. kaempferi was discussed with synthetic judgment of pulping-making properties, fiber characters and physical strength of pulp of L. kaempferi with different age in sub-tropical area. The result indicated that Technology Maturity Age of L. kaempferi is 13-22a. Furthermore, the differences of pulping properties of L. kaempferi in various site index, stand density and different parts of the tree(upper, middle and lower parts of trunk and branch) were researched by ANOVA analysis. The results showed that there are no different between L. kaempferi of various site index and stand density, however, the pulping-properties of trunk is better than branch significantly. Moreover, the difference between different parts of trunk is not significant.The Economical Maturity Ages for L. kaempferi were analyzed by Improved-DCF method (Land expectation value, Annual net present value and Inner return of rate) and Real Options method which is advanced method at present, based on discussion of the appreciate discount rate for forestry management. The results indicated that the LEV maturity ages for L. kaempferi in site index 13,15,17,19 and 21 were 25-26a、24-26a、22-24a、20-23a、20-21a respectively; the corresponding ANPV maturity age were 24a、23-24a、21-22a、18-21a、18-19a respectively and the corresponding IRR maturity age were 26-27a、24-26a、21-24a、18-22a、17-19a respectively; Meanwhile, the RO maturity age were 25-27a、24-26a、22-23a、21-22a、19-22a respectively at the current pulpwood price level. The results also showed that the L. kaempferi plantation with higher site index or stand density (within reasonable range) usually had more profitable gain and shorter economical maturity age.Sensitivity analysis was evaluated to L. kaempferi in various site index and stand density with the changing of pulpwood price, discount rate and the cost of plantation management. It was indicated that the economical gain of pulpwood plantation would decreased with the increase of discount rate and decrease of pulpwood price and management cost; Furthermore, the most influential factor is discount rate, followed by pulpwood price and management cost.The Harvest Price Thresholds and the Shortest Rotation Age were concluded by discussing the economical maturity age of L. kaempferi with Real Options method. The Harvest Price Thresholds means the lowest wood price to harvest a plantation at a certain age, which means Harvest Option should be chosen when the wood price was higher than the price threshold at a certain age, otherwise Wait Option (deferring harvest) should be chosen. The Shortest Rotation Age means the shortest rotation age of a plantation as the wood price keeping at a high level, in other words, the Wait Option should be taken whatever the wood price is when the stand age to be smaller than the shortest rotation age. The results showed that the Harvest Price Thresholds decreased with the increasing of stand density and the Shortest Rotation Age of L. kaempferi plantation with the site index 13,15,17,19 and 21 were 22-25a、21-23a、19-21 and 17a respectively.The Integrated Decision-Making System of the optimal rotation age of L. kaempferi was established by Analytic Hierarchy Process (AHP) technique, following the concept of“Based on technology maturity, focused on economical maturity age, and take Quantitative maturity into consideration”. The optimal rotation age of various L. kaempferi plantation with different site index were figured out by the weight of various factors determined by Integrated Decision-Making System, and it was indicated that the optimal rotation age of L. kaempferi plantation with site index 13 and 15 were18-19a, and the plantation with site index 17,19 and 21 were 17-18a.The Optimal Rotation Age is a complex integrated multiple-criteria problem which needs to be evaluated by various maturity criteria. Moreover, the economical maturity problem is a focus issue in forest management discussed by researchers all over the world. Furthermore, it will be the hotspot and focusing point that considering the optimal rotation age from economical maturity aspect in China, because the rich timber forest resource and the accelerating process of market. In this study, the Real Options method was the main method to cope with rotation age, as the pulpwood price fluctuation and management flexibility were taken fully account, which has provided flexible and sound management strategy and could be viewed as a preferable method to evaluate forest economical maturity age.As mentioned above, the Integrated Decision-Making system and various maturity ages of L. kaempferi concluded in this study have provided guidance approach and theoretical basis for L. kaempferi management and production in sub-tropical area in China.更多还原