基于模拟退火算法邻域搜索的森林抚育空间经营规划研究

The research of forest tending were generally studied using the strategies of quantitative and qualitative comparison methods on the scale of sample plots, ignoring the potential influences of the temporal and spatial configuration of forest management actions. Therefore, the optimal forest tending actions may be not applied directly into the whole region without carefully assessing their effects of the structure and function of forest ecosystems. Thus, the overall goal of this project is to develop a spatial-explicitly multipurpose forest tending planning model for a large forest region in northeast China. The specific objectives in this project are therefore to 1) investigate the optimal forest structures characteristics and tending intensity of the main forest types within different development stages; 2) develop multipurpose forest tending planning models mainly focusing on the temporal and spatial configuration of forest tending actions, timber production, net carbon sequestration objectives; 3) improve the performances of simulated annealing in complex forest planning problems using the strategies of neighborhood search techniques; 4) establish multipurpose forest tending planning platform (FMPP) by integrating stand-level growth and yield simulation systems and multipurpose forest tending planning models into a simulated annealing search process; 5) evaluate the effects of various forest tending strategies and constraints on the structure and function of forest ecosystems. The achievements of this project can provide some insights in forming the optimal forest tending plans within this region.

传统森林抚育研究多是基于样地尺度上的对比试验展开的，未充分考虑抚育措施时空分布对整个森林生态系统所造成的潜在影响，因此能否直接将其推广到区域尺度以及其将产生何种作用和效果仍需进一步检验。为此，本项目以大兴安岭地区塔河林业局盘古林场为例，在全面分析各林型不同演替阶段的最优林分结构特征及抚育措施的基础上，采用效用函数理论建立能够兼顾森林抚育措施空间聚集、木材生产和碳储量的多目标规划模型；以此为基础，系统研究基于邻域搜索的模拟退火算法性能优化提升技术，进而建立大兴安岭不同森林多目标抚育经营空间规划模拟平台，并系统模拟、评价和比较不同抚育策略和约束条件对森林生态系统结构和功能的影响，为大兴安岭地区林场尺度森林抚育经营方案的编制提供理论依据和技术支持。

全球气候变化对人类生存环境造成了显著影响。因此，如何在保证人们木材需求的前提下，最大限度的发挥森林的碳汇功能一直是国内外学者研究的重点和难点。为此，本项目着重从两个层面开展了森林碳汇和木材的复合经营研究。在林分尺度上，（1）证明了合理林分结构能够显著影响兴安落叶松单木直径生长，即当角尺度、混交度和竞争指数每增加10%时，其对应的胸径生长量依次为：+3.62 cm、+4.71 cm和−0.73 cm；（2）提出了一种能够兼顾林分空间和非空间结构的调整优化模型，在落叶松天然林、阔叶红松林、蒙古栎林和次生林中的模拟结果表明：10%的抚育强度能够显著提升林分综合结构指数5~10%左右。在景观尺度上，（3）基于复杂的森林空间规划问题，系统研究了模拟退火算法的性能提升策略和参数优化方法，结果表明邻域和逆转搜索均能显著提升模拟退火算法的目标解质量，此外各种改进策略的参数值均随着林分数量呈显著的多项式或指数函数；（4）建立了以森林抚育措施为基础、能够兼顾森林碳汇和木材经营目标的规划决策模型，并定量模拟了不同空间约束、资源约束和碳价格对森林经营决策的影响，模拟结果表明适当提升碳价格或执行较为严格的采伐约束能够实现森林碳汇和木材生产目标的综合效益最大化。项目成果对提升我国森林质量具有重要的支撑作用。