线性规划、模拟退火和遗传算法在杉木人工林可持续经营中的应用和比较

以杉木人工林为例 ,介绍了线性规划、模拟退火和遗传算法在编制森林经营方案过程中的应用和比较 ,同时介绍了一种通用的可以处理绝大多数的森林经营模型。采用Hui(1997)的生长和间伐模型来模拟林分的生长、间伐和发展过程。线性规划、模拟退火和遗传算法三者适用于不同的场合。当约束条件都比较宽松时 ,线性规划也有可能得出整数解 ,但不一定就能够避免林分分割经营 (整数解 )。要获得整数解 ,尤其是在林分数目很大的时候 ,可以采用模拟退火和遗传算法。如果允许林分分割 ,线性规划的结果一般可以获得最好的目标方程值。     

森林经营规划中优化算法应用研究进展

林业的可持续发展是一个热门话题,人们对森林的生态效益和社会效益要求越来越高,问题越来越复杂,行之有效的经营方案可以使森林的生态、经济、社会效应协调发展。森林采伐规划是一个组合优化问题,启发式优化算法的广泛应用,实现了森林资源的动态管理,使森林最终达到可持续的理想状态。本文简要地介绍了蒙特卡洛整数规划,模拟退火算法,遗传算法,禁忌搜索算法等几种主要的优化算法,对其在国内外的应用状况进行了综述,并对森林采伐规划中优化算法的应用提出了存在的问题及建议。     

基于模拟退火算法逆转搜索的森林空间经营规划

【目的】研究逆转搜索策略对模拟退火算法性能的提升作用,为复杂森林经营规划问题的优化求解提供技术支撑。【方法】以大兴安岭塔河林业局盘古林场森林空间收获安排问题为例,以模拟退火算法1-邻域和2-邻域技术为基础构建逆转搜索过程,并将其应用于具体的森林经营规划实践。规划模型以10年规划期内的木材均衡收获为目标函数,根据经营措施选用不同空间约束形式,对抚育措施采用面积限制模型,对皆伐措施采用单位限制模型,2种模型均满足3年的绿量约束期。【结果】对于最小化森林经营规划问题而言,逆转搜索中不同邻域间的交互次数对规划结果影响不显著,但其平均目标函数值均显著低于传统模拟退火算法1-邻域(P001)和2-邻域(P001),而算法优化时间分别比1-邻域和2-邻域增加约5和2倍,逆转搜索策略具有显著的优越性能和广泛的应用前景;最优森林经营方案表明,整个规划期(10年)内预计可收获木材约500×10~5m~3,其中抚育出材量312×10~5m~3,抚育林分面积占林场总面积的1094%,皆伐出材量188×105m3,皆伐林分面积占林场总面积的102%,该方案能够满足森林可持续经营的目标。【结论】逆转搜索是一种高效、稳定的优化求解技术,能够满足复杂森林经营规划问题的需要,可为森林经营方案的编制提供技术支撑。     

一种适用于森林管理变量的并行模拟退火算法

针对森林经营管理的复杂性问题,通常以模拟实地的虚拟森林环境作为实验区,运用模拟退火算法工具运营管理森林。由于传统算法存在执行时间长、收敛速度慢等一系列缺点,本文展示了一种在线的并行模拟退火算法及其优化策略。在独立搜索与合作搜索策略下优化并行算法,独立搜索时,彼此线程间不进行通信,各个线程独立的运行各自的马尔科夫链,在各线程运行结束后,主线程再统一接收各自线程的局部优化解,经过比较进而得出全局最优解;合作搜索时,先通过若干步的退火步骤,线程根据情况产生2种退火链通信阶段:同步通信裢阶段和异步通信链阶段,实时更新结果。经过对比分析得出,串行模拟退火算法比并行算法的收敛速度快;并在Solomon提供的标准测试集上对并行算法的性能进行测试,分析进程数目对代价大体呈反比的趋势,在理论和实验上,表明并行策略可实现高效低成本的森林经营管理。     

林龄空间理论与减反率法应用初探——湖南省会同集体林区森林采伐量预估研究

本文以会同县过去5年森林采伐情况为例,论证了应用林龄空间理论——减反率法预估集体林采伐量的可能性,并提供一个线性规划经营方案作为对照。通过比较,认为在规划期较长的条件下,减反率法预估采伐量与线性规划方案所得收获量一致。     

林业科学研究总目次

第　 1　期细叶桉种源—家系综合选择的研究徐建民 ,陆钊华 ,李光友等 ( 1)…………………基于GIS太阳直接辐射模型的研究谢阳生 ,唐小明 ,黄水生 ( 8)……………………中国东北杨树上的木腐菌戴玉成 ,范少辉 ,魏玉莲等 ( 13)………………我国不同森林立地带土壤中苏云金芽孢杆菌cry基　因资源研究张永安 ,宋福平 ,戴莲韵等 ( 19)……Tabu搜索法在森林采伐量优化问题中的应用陈伯望 ,惠刚盈 ,KlausvonGadow( 2 6 )…………昆明地区白蜡虫自然种群天敌种类及其危害调查赵杰军 ,王自力 ,叶寿德等 ( 32 )…………………福建柏苗期生物量种源…     

森林经营单位合理年采伐量分析研究

森林采伐是调整森林结构、改善森林质量、提高森林功能的关键措施。科学的采伐管理是实现森林可持续经营的重要途径。当前我国森林采伐实行采伐限额管理制度,森林经营单位的年采伐限额原则上按森林经营方案确定的合理年采伐量核定。因此测算和确定合理年采伐量是经营方案编制的重要内容。以吉林省红石林业局为研究区,对森林经营单位如何科学测算和确定合理年伐量进行深入分析研究,以期在技术和方法上为森林经营单位编制森林经营方案及测算合理年采伐量提供参考。     

对限额采伐量的探讨

正确计算限额采伐量,是编制完整的、科学的森林经营方案的前提。计算限额采伐量时要注意两个问题:一是设计产量,二是出材率。在考虑设计产量时,我们一定吸取历史经验教训,根据林业生产实践调整设计产量,使所计算的限额采伐量接近实际。正确使用出材率系数也是计算限额采伐量的重要因素,应给予重视。如果出材率使用不当,势必影响限额采伐量的正确计算,以至影响经营方案的编排。     

在编制国营林场森林经营方案中如何计算森林采伐量

<正> 根据“森林法”的规定,国营林业企业事业单位,应编制森林经营方案,报上级主管部门批准后执行。这是实现科学经营森林,加强国营林场建设的重要措施。在编制经营方案的过程中,除总结历史经验,搞好林场森林经营和建设布局外,重要的内容就是计算和确定合理的森林采伐量(因抚育间伐和林分改造采伐量的计算,按其他要求和办法进行,本文主要探讨国营林场现阶段经营采伐量的计算问题)。如果这个问题处理得不好,势必影响林场的建     

计算机模拟退火优化算法监测模型及模拟试验

计算机模拟退火优化算法的主要作用是在一个大的搜索空间中寻找最优解或近似最优解。它通过模拟退火的方式,跳出局部最优解,从而有机会找到全局最优解。监测模型中的目标函数通常是非凸的,意味着存在多个局部最优解。计算机模拟退火算法可以帮助跳出局部最优解,并在整个搜索空间中找到全局最优解或近似最优解。基于计算机模拟退火优化算法的基本原理,详细介绍该算法的退火过程以及计算流程,并从参数优化、鲁棒性改进等方面,指明该模型的优化与应用方向,以提高监测模型的性能和效果。     

Tabu search optimization of horizontal and vertical alignments of forest roads

This article describes a program for optimizing horizontal and vertical alignments of forest roads using Tabu search, a modern heuristic technique. Once a series of intersection points (IPs) is selected manually, the program generates alternative horizontal and vertical alignments. The program precisely generates ground profile and cross sections using a high-resolution digital elevation model (DEM) derived from light detection and ranging (LiDAR) data. It accurately calculates earthwork volumes for curved roadways using the Pappus-based method. The program also estimates construction and maintenance costs. Tabu search optimizes forest road alignments based on the total costs. The application of the program to part of Capitol State Forest in Washington State, USA, indicated that the program successfully found better alignments than manually selected initial alignments. The effect of initial solutions and the number of iterations on the Tabu search process was examined. The result showed that the solutions were improved using the best solutions with the smaller number of grade change points as the initial solutions. It also showed that a small number of iterations could be used to reduce computation time due to the fact that Tabu search is based on a gradient search technique. Finally, the Dijkstra method was examined to find initial solutions without manually initialized solutions. The program, when combined with the Dijkstra method, could find similar-quality solutions from manually initialized solutions. The program will become useful with further tests and verifications.     

森林采运系统动力学模型研究

为了分析森林采运系统的效率和成本,本文选择系统中关键的采—集过程,利用系统动力学的方法建立模型,进行计算机仿真模拟。结果显示,以特定时间范围内完成一定工作量为前提,系统运行的效率和成本与初始设备的投入量关系不大,与设备条件、外部条件、林木条件等关系很大。但初始采造设备的投入量会影响集材设备的运行效率和成本。在实际生产中,首先应根据林木条件和外部条件选择合适的设备,这样才能使得运行效率最高而成本最低;其次在设备的安排上,应充分保障采造设备,但也不应使其生产力与集材设备的生产力相差过大,否则会造成后期集材设备需求激增等问题。     

基于森林空间规划问题的模拟退火算法参数敏感性研究

[目的]以森林空间收获安排问题为基础,系统探讨模拟退火算法参数(初始解数量、初始温度、降温速率和每温度下重复次数)设置对森林空间规划问题目标解质量的影响。[方法]规划模型以10个5年规划分期内的最大化木材收获为基本目标,同时满足均衡收获和最大连续采伐面积约束。模拟数据由5个假设的栅格数据组成,共产生了3 300 81 600个0-1型决策变量。[结果]表明:各规划问题目标函数值的平均变异系数仅在0.18%14.95%间波动,说明模拟退火算法优化结果的高度稳定性;每温度下重复次数和初始温度分别与林分数量呈显著的多项式(R~2=0.85)和指数(R~2=0.66)关系,而降温速率则与林分数量倒数呈显著的多项式(R~2=0.98)关系,初始解数量虽不受林分数量影响,但至少应维持在500次以上。同时,研究还表明规划问题规模不仅显著影响各参数的取值,同时还显著影响算法获得满意解概率(PN)和求解效率(RE),其中满意解概率随林分数量的增加而呈显著线性增加趋势(R~2=0.98),但求解效率则呈显著线性下降趋势(R~2=0.55)。[结论]模拟退火算法优化结果具有高度稳定性,能够适应复杂森林规划问题的需求;模拟退火算法优化结果对参数设置和林分数量具有高度的敏感性,因此森林经营决策人员在采用模拟退火算法解决具体的森林规划问题时应慎重选择各参数的取值,以确保规划结果的稳定性和可靠性。     

A deterministic harvest scheduler using perfect bin-packing theorem

The use of heuristic techniques in forest planning has been promoted by the need to solve complex problems that cannot be solved using mixed integer programming. We proved that for merchantability standards ensuring the perfect bin-packing theorem (PBPT), the maximum volume that can be harvested annually equals the sum of the maximum MAI of the stands. The method accommodates optimality criteria at the stand level, regarded as maximum MAI, and at the forest level, regarded as maximum annual allowable cut. We scheduled the harvesting by adjusting the first fit decreasing algorithm (FFD) to the PBPT conditions. When PBPT conditions were not met, we developed a mixed integer programming solution to adjust the merchantability standards of the stands to the distributional requirements of the PBPT, an adjustment that ensured the optimal performance of the FFD. The adjusted FFD was compared with linear programming (LP) and simulated annealing (SA) using two harvesting ages (i.e., one based on MAI maximization and one determined as the minimal age) and the same set of spatial temporal constraints for three areas in north-eastern British Columbia, Canada. We found that the adjusted FFD performed 100 times faster than SA and for annual allowable cut (AAC) supplied results that were more homogenous and at least 10% greater than the AAC supplied by SA. Furthermore, the adjusted FFD seemed to be relatively insensitive to spatial constraints (i.e., adjacency), while SA displayed a 70% reduction in AAC in response to an increase in adjacency delay from 1 year to 20 years. The results suggest that both adjusted FFD and SA are impacted by the selection of the harvesting age, but the adjusted FFD could still outperform SA.     

模拟退火法在汪清林业局森林可持续经营决策中的应用研究

以异龄林为对象,应用模拟退火法,探讨了确定林分水平上异龄林最佳可持续经营决策的方法,以期为我国森林可持续经营的生产实践提供参考。     

Nutrient exports under different harvesting regimes in fast-growing forest plantations in southern Europe

In the humid and temperate areas of southern Europe, forest plantations are dominated by fast-growing species (Eucalyptus globulus, Pinus radiata and Pinus pinaster), which are grown on acidic soils with low reserves of available nutrients. In this study the amounts of nutrients exported from the plantations under different regimes and intensities of harvesting were evaluated and, on the basis of the results obtained, silvicultural management methods aimed at improving the nutritional status of the plantations were proposed. We found high ratios between nutrients exported by harvesting and those available in soil stores, indicating limitation for P, Ca and Mg over the long term, which is consistent with frequently found deficiencies of these nutrients. Current harvesting practices (removal of stem wood and bark) result in high rates of export of P, K, Ca and Mg, especially in eucalypt plantations, because of the high productivity and low nutrient efficiency of this species. Comparison of the amounts of nutrients exported by harvesting, with natural inputs (rainfall and weathering) and outputs (stream water), suggests that intensive exploitation of these plantations may result in negative budgets, especially if whole tree harvesting is carried out. The application of fertilizers containing P, Ca and Mg should be encouraged in all cases to favour the return of nutrients, especially where logging residues are extracted. The cost of harvesting in terms of nutrients can also be reduced by careful selection of the tree species planted and of the tree fractions harvested and by reducing the intensity of harvesting.     

Heuristic planning techniques applied to forest road profiles

Two heuristic techniques, the genetic algorithm (GA) and Tabu search (TS), both with an embedded linear programming routine for earthwork allocation, were compared to a manually designed forest road profile. The manually designed road length was 345.7m and its average gradient was 14.1%. The best costs of the profiles designed by GA and TS, without changing the placement of control points, were less than that designed manually. The best cost found by GA was almost the same as the global optimum solution. While TS could not find a better solution than GA, it usually found a good solution in less time. It was not possible to search all alternatives by changing the placement of control points and find the global optimum solution within a reasonable time. However, it can be concluded from the results that both GA and TS found good solutions within a reasonable time. Since it is not possible to manually evaluate many alternatives, road designers should find heuristic techniques helpful for design of the road profile. Moreover, the effect of the number of control points on construction costs was examined. The results indicated that increasing the number of control points reduces the construction costs. However, driving safety and comfort might be decreased.     

Anthropogenic alterations of genetic diversity within tree populations: Implications for forest ecosystem resilience

Healthy forests provide many of the essential ecosystem services upon which all life depends. Genetic diversity is an essential component of long-term forest health because it provides a basis for adaptation and resilience to environmental stress and change. In addition to natural processes, numerous anthropogenic factors deplete forest genetic resources. Genetic losses could be particularly consequential now because robust resilience is needed to respond to a growing number, variety, and frequency of stress exposures. Silvicultural management that selectively removes trees (and their genes) from forests may be another force reshaping forest gene pools. Although data concerning the influence of silvicultural management on genetic resources in temperate forests is somewhat mixed, through the genetic assessment of long-term silvicultural treatments within an eastern hemlock (Tsuga canadensis) forest, and computer-based simulated harvests of a genetically mapped eastern white pine (Pinus strobus) stand, we found that the selective removal of trees can alter gene frequencies. Due to an association with phenotypic characteristics used to guide harvests, the frequencies of rare alleles appeared particularly vulnerable to manipulation. Depending on the selection criteria used, rare allele frequencies either remained steady, decreased, or increased relative to study controls. Although harvest-associated genetic losses are possible, our data suggests that management can also sustain or enhance genetic richness. Similar to studies within temperate ecosystems, recent research in tropical forests underscores the potential influence of harvesting on the genetics of tree populations. In addition to efforts to reduce controllable sources of ecosystem stress (e.g., high pollutant exposures), management options should be evaluated that may bolster forest ecosystem resilience by preserving levels of genetic diversity within forests.     

Challenges in developing and implementing a decision support systems (ETÇAP) in forest management planning: a case study in Honaz and Ibradı, Turkey

Decision support systems (DSSs) are indispensable tools in preparing a forest management plan for a better combination of multiple forest values. This study attempted to develop and explain a stand-based forest management DSS (Ecosystem-based multiple-use forest planning [ETÇAP]) comprising a traditional simulation, linear programming (LP), metaheuristics and geographic information system. The model consists of five submodels; traditional management approach to handle inventory data, an empirical growth and yield model, a simulation to conceptualize management actions, a LP technique to optimize resource allocation and a simulated annealing approach to directly create a spatially feasible harvest schedule. The ETÇAP model has been implemented in a comparative two case study areas; Denizli–Honaz and Akseki–Ibrad?. Both simulation and optimization models outperformed to the traditional management plan. The periodical change of growing stock, allowable cuts, carbon sequestration and water production are used as performance indicators. The results showed that more amount of wood could be harvested over time compared to traditional level of harvesting. It could be concluded that various management strategies allowed managers to stimulate more decision options for better outputs through intertemporal trade-offs of management interventions as the model provided tools to quantify forest dynamics over time and space. Challenges exist to establish the functional relationships between forest structure and values for better quantification and integration into the management plans.     

Formation of harvest units with genetic algorithms

Operational planning is normally based on stands as the primary unit of treatment. In recent years, interest has been directed towards the use of smaller area units such that the formation of treatment units becomes part of the operational planning. Here, the method of genetic algorithms was used in order to delineate harvesting units in a forest described as a grid of 20 m × 20 m pixels. Remote sensing data and inventory plots were employed to derive pixel estimates of forest variables. Appropriate parameter settings for the algorithm were investigated for two cases that consisted of 26 × 25 pixels. Based on the experience from these tests, the algorithm was employed in forming treatment units in an area encompassing 100 × 100 grid cells, or 400 ha. Due to the size of the problem, a two-stage procedure was suggested. The solutions of the genetic algorithm were compared with a heuristic, a cell removal algorithm, that was proposed in earlier studies of treatment unit formation. The genetic algorithm performed better than the heuristic for all the cases that were tested.