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11.
Atsushi Yoshimoto 《Journal of Forest Research》2001,6(1):21-30
The objective of this paper is to investigate potential use of a spatially constrained harvest scheduling model for biodiversity
concerns. Change in the degree of biodiversity is represented only by spatial characteristics of harvesting patterns of forest
stands with different exclusion periods applied to adjacent forest stands. A spatially constrained harvest scheduling model
called SSMART (Scheduling System of Management Alternatives foR Timber-harvest) is used for the analysis. It is one of the
heuristics to solve a spatially constrained harvest scheduling problem by using the partitioning heuristic. The algorithm
incorporated into SSMART is designed to seek a solution for a multicriteria problem with present net value maximum, meeting
spatial feasibility and minimizing period-to-period harvest flow fluctuation, approximating even-flow constraints within the
0–1 integer programming framework. Our experimental analysis shows that the longer exclusion period, the less the harvest
flow level and the total present net value are derived and the more heterogeneous the forest structure becomes in terms of
the forest stand age distribution. It is also shown that the three exclusion period results in a stable forest stand age distribution
over the time horizon for our experimental forest.
This research supported by the Grants-in-Aid for Scientific Research (No. 09041071) from the Ministry of Education, Science,
Sports, and Culture of Japan. 相似文献
12.
检查法林分生长预测及择伐模拟研究 总被引:5,自引:0,他引:5
检查法是一种适合于异龄林经营的集约作业方法,由于目前试验时间还较短(第1择伐周期1987-1992年),需要对其长期经营效果作出预测。文中提出了一种修正参数预测模型(MPPM)和线性规划方法相结合对于林分进行生长预测和择伐模拟研究的方法。拟合林分直径分布采用了形状灵活的Weibull分布形式,使得这种方法很适合于异龄林分(反J形直径分布)的生长预测(当然也适于同龄林),特别是当径阶株数出现突然变化 相似文献
13.
14.
In the Philippines, smallholder farmers have become major timber producers. But the systems of timber production practiced
have several limitations. In intercropping systems, the practice of severe branch and/or root pruning reduces tree-crop competition
and increases annual crop yields, but is detrimental to tree growth and incompatible with commercial timber production. In
even-aged woodlots, lack of regular income and poor tree growth, resulting from farmers’ reluctance to thin their plantations,
are major constraints to adoption and profitable tree farming. In the municipality of Claveria, Misamis Oriental, the recent
practice of planting trees on widely spaced (6–8 m) contour grass strips established for soil conservation suggests ways to
improve the adoptability (i.e., profitability, feasibility and acceptability) of timber-based agroforestry systems. Assuming
that financial benefits are the main objective of timber tree farmers, we develop a simple linear programming (LP) model for
the optimal allocation of land to monocropping and tree intercropping that maximizes the net present value of an infinite
number of rotations and satisfies farmers’ resource constraints and regular income requirements. The application of the LP
model to an average farmer in Claveria showed that cumulative additions of widely spaced tree hedgerows provides higher returns
to land, and reduce the risk of agroforestry adoption by spreading over the years labour and capital investment costs and
the economic benefits accruing to farmers from trees. Therefore, incremental planting of widely spaced tree hedgerows can
make farm forestry more adoptable and thus benefit a larger number of resource-constrained farmers in their evolution towards
more diverse and productive agroforestry systems. 相似文献
15.
根据区域生态经济学原理 ,结合晋西石楼县生态林业工程建设的实践 ,分析了县域土地资源利用现状 ,进行了土地利用多目标综合规划 ,阐述了生态林业工程土地合理利用的途径 ,并对其战略决策进行了分析。 相似文献
16.
根据1993年省森林资源清查、森林资源消耗量及消耗结构的调查资料,以可持续发展的理论为指导,采用线性规划对我省的林种结构进行了研究。研究结果:河南省现阶段的林种结构应为:用材林∶防护林∶经济林∶薪炭林∶特用林=349∶159∶237∶211∶44。 相似文献
17.
The cutting technic for thePinus elliottii plantation of the multi-benefit management pattern in the hilly region of Jiangxi Province was studied by establishing the
model of growth progress according to Richards function and simulating the tending cutting on computer by use of dynamic programming.
The results showed that the best time for the initial thinning was at tree age of 8–10 and final cutting was at tree age of
25. The optimal thinning project was 3 times of thinning cutting including the first thinning, and the thinning time was at
tree ages of 8, 12 and 16, respectively. Their thinning intensities were separately 950, 700 and 300 trunks per hectare, and
the preserved density was 550 trunks per hectare until the final cutting
Foundation item: This study was supported by Natural Science Foundation of Jiangxi Province (A grant 0330023)
Biography: WANG Qing-chun (1970-), male, Ph. Doctor, Senior Engineer in Academy of Forest Inventory & Planning, Jiangxi, Nanchang 330046,
P.R. China.
Responsible editor: Song Funan 相似文献
18.
The availability of public recreational facilities is being threatened by growing demands, limited supplies, and declining
government funding. In response to these pressures, the economic potential of agroforestry for supplementing operating budgets
of public recreational parks is examined in a case study park consisting of 324 hectares. Agroforestry enterprises native
to the area were selected for development on 70 hectares of the site. Linear programming was used to determine the optimum
combinations of 23 agroforestry regimes composed of the following activities: 1) conventional forestry planting, tree density
of 1682 trees/hectare, 2) the selected agroforestry planting with hay, tree density of 1495 trees/hectare, 3) the selected
agroforestry planting with grazing, 4) hay production, and 5) rental of pasture for grazing. The objective function of the
study was to maximize the net present value of the study site subject to land, labor, capital, and minimum annual income constraints.
The preferred optimal regime generated $1782 per hectare from an agroforestry planting configuration of 1495 trees/hectare
with 75 percent hay, 25 percent grazing, and no annual income requirements. Minimum annual income requirements of $2400 and
$4800 were feasible but suboptimal from a net present value criteria. The study found that agroforestry could be used to privatize
selective activities of public recreational parks and thus enable public agencies to provide these facilities more effectively. 相似文献
19.
A mathematical model for generating land-use allocation alternatives for agroforestry systems 总被引:2,自引:0,他引:2
Guillermo A. Mendoza 《Agroforestry Systems》1987,5(4):443-453
Agroforestry has been considered a viable land-use system particularly in the tropical regions. In developing or designing agroforestry systems, various concerns have to be addressed namely: (1) economic; (2) biological and physical; and (3) silvicultural and ecological considerations. This paper addresses these concerns from an interdisciplinary perspective. A land-use allocation model which ensures the simultaneous consideration of these concerns is proposed. 相似文献
20.
顾小妹 《河北北方学院学报(自然科学版)》2015,(2):4-7,12
对曲面为正三角形网格矩形底面扁球面单层网壳,用拟壳法建立非线性动力学方程,在固定夹紧的边界条件下,给出满足边界条件的动态解。通过Galerkin法得到该问题的非线性动力学方程,用Floquent指数方法研究系统的分岔问题,讨论了平衡点(奇点)领域的稳定性问题。并且通过数字仿真绘出了不同平衡点处系统的分岔图,指出系统在动静载荷作用下平衡位置的变化情况。 相似文献