Dynamic programming for optimization of timber production and grazing in ponderosa pine
Dynamic programming for optimization of timber production and grazing in ponderosa pine
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优化黄松木材生产和放牧的动态规划
DOI：
10.1093/forestscience/28.3.517
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发表时间：
1982
期刊：
影响因子：
1.4
通讯作者：
D. Hann
中科院分区：
文献类型：
--
作者：
K. Riitters;J. Brodie;D. Hann
本文提出了用年龄、断面积、株数和间伐时间这四个描述因子来优化同龄黄松间伐轮伐的动态规划方法。因为木材产量和放牧产量都是林分密度的函数，所以两种产出--牧草和木材--都可以得到优化。土壤的期望值为单一和联合生产的推导和比较，动态变化的影响，在旋转的两种产品的相对价格。根据相对价格和贴现率，最大土壤期望值将由单独的木材、单独的放牧或联合生产的最佳时间表提供。讨论了两种产出的相对成本和价值对管理的影响。森林SCl. 28：517-526。Hann和Brodie（1980）讨论了动态规划（DP）在同时确定间伐强度和旋度方面的应用。典型的DP制剂（例如，Brodie和Kao（1979）在网络中定义的每个时间阶段，在几个状态描述符的每个离散水平上最大化木材采伐的累积净现值。尽管DP制剂在状态描述符和治疗选项的数量方面变得越来越复杂（例如，Kao 1980），目标函数通常仅基于木材的价值。本文应用动态规划法同时确定美国黄松的间伐强度和轮伐期。当目标函数中考虑木材和饲料两个输出时。将联合生产与单独生产每种产品进行了对比，并讨论和论证了相对值变化的影响。Burde（1974）对亚利桑那州一个假设的黄松林的木材和饲料生产进行了案例研究。他的结论是，森林应根据主要用途的概念进行管理，将商业牧场管理用于饲料生产，将商业林地管理用于木材生产，将用于这两种目的的次边际土地管理用于其他用途。我们解决的问题是，确定间伐制度，共同最大限度地提高回报，从放牧和木材收获的同一单位，
Dynamic programming procedures are presented for optimizing thinning and rota- tion of even-aged ponderosa pine by using the four descriptors: age, basal area, number of trees, and time since thinning. Because both timber yield and grazing yield are functions of stand density, the two outputs--forage and timber---can both be optimized. The soil expectation values for single and joint production are derived and compared, and the impact of dynamic changes in relative price of the two products over the rotation is shown. Depending on relative prices and discount rate, the maximum soil expectations will be provided by timber alone, grazing alone, or an optimal schedule of joint production. Impacts of relative costs and values of the two outputs on management are discussed. FOREST SCl. 28:517-526. THE APPLICATION OF DYNAMIC PROGRAMMING (DP) for the simultaneous deter- mination of thinning intensity and rotation has been discussed by Hann and Bro- die (1980). A typical DP formulation (e.g., Brodie and Kao 1979) maximizes the cumulative net present value of timber harvested over discrete levels of each of several state descriptors at each time stage defined in the network. Although DP formulations are becoming increasingly complex in terms of number of state descriptors and treatment options (e.g., Kao 1980), objective functions usually have been based on the value of timber only. In this paper, we demonstrate the use of dynamic programming for the simultaneous determination of thinning in- tensity and rotation for ponderosa pine (Pinus ponderosa Laws.) when two out- puts, timber and forage, are considered in the objective function. Joint production is contrasted with production of each product independently, and the impact of changing relative values is discussed and demonstrated. Burde (1974) conducted a case study of timber and forage production for a hypothetical ponderosa pine forest in Arizona. He concluded that the forest should be managed under the concept of dominant use with commercial rangeland managed for forage production, commercial forest land managed for timber pro- duction, and lands submarginal for either purpose managed for yet other uses. The problem we address is that of determining the thinning regime that jointly maximizes the returns from both grazing and timber harvest on the same unit of