Forest Planning Models Research Articles

Considering Intergenerational Equity in Linear Programming-Based Forest Planning Models with MAXMIN Objective Functions

Abstract This paper describes alternative approaches to formulating linear-programming-based forest planning models. These approaches consider a form of equity between current and future generations, as represented by the periods in a planning horizon. Both nominal net revenue in each period and each period's present net worth with values discounted relative to each period, are used as criteria for welfare. The minimum present net worth or net revenue outcome obtained for the set of periods is maximized. The approaches are different. Using present net worth relative to each period as a criterion allows for a concern for economic efficiency and allows variation in net revenue. Using net revenue focuses on a more even distribution of net revenue between periods. The approaches are tested in a case study, and the results are compared to those from a standard approach of maximizing present net worth relative to the first period. The results suggest that the approaches could be useful in a forest planning context, either as an alternative to standard approaches or as a means of generating relevant information. For. Sci. 45(3):366-373.

A Decision Support System for Incorporating Wildlife Habitat Quality into Forest Planning

Abstract We developed a decision support system to address wildlife habitat quality in the strategic forest planning process. The process involves projecting wildlife habitat attributes using a growth and yield model, combining the attributes into an index of structural habitat quality, generating yield tables of structural habitat quality that can be constrained or optimized in the forest planning model, and relating prescriptions for each forest planning analysis area back to the habitat attributes. The result is a map of habitat components. This mechanism is considered the first step in our wildlife habitat assessment procedure in that it focuses on within-stand or within-analysis area structures. Since many wildlife species depend on multiple stands or analysis areas and the spatial arrangement of habitat components to meet their life requisites, the second step in our habitat assessment procedure is to apply spatially explicit wildlife habitat models to the mapped planning solution. The decision support system offers the capability to evaluate the effects of alternative management strategies on wildlife habitat in the context of a forest planning model solution. West. J. Appl. For 14(2):91-99.

Measuring the efficacy of adjacency constraint structure in forest planning models

This paper examines various structural representations of adjacency conditions in forest planning problems. It will be shown that alternative representations can rival traditional approaches, which is counter to much of the mathematical modeling and formulation literature. Analysis was conducted on a number of forest planning problems in order to draw some general conclusions on adjacency constraint representations. This is the first time that these structures have been compared in a comprehensive way. This paper provides insights into solution performance using different constraint structures and will help further the development of improved methodologies for analyzing environmental problems that must incorporate increased spatial detail.

A Column Generation Algorithm for Solving General Forest Planning Problems with Adjacency Constraints

Abstract An algorithm is presented for solving general forest planning models when spatial relationships, in particular adjacent constraints, are considered. We solve a master linear program with a column generation approach. The generation of columns is done by solving a stable set problem. To preserve the adjacency properties, fractional solutions in the master problem are rounded off to integrality through a heuristic procedure. Computational experience on medium-sized problems showed that solutions with small deviations from the optimal could be obtained with moderate computational effort. For. Sci. 40(1):142-161.

Determining the effects of harvesting guidelines on the age-class profile of the residual forest

Chromatic scheduling was used to demonstrate that harvest unit adjacency constraints can be translated into age-class profile constraints that are suitable for regulating the rate of harvest in strategic forest planning models. The advantage of the age-class approach is that strategic harvest rates will reflect the spatial constraints without the onerous task of designing and scheduling cut blocks for the entire forest. Other factors that are relevant to determining the steady-state age-class profile are the exclusion period and the width of the leave strip between any two harvest units. Through the analysis of four spatial data sets it was observed that the chromatic number decreases as the block size increases; however, the absolute block size was not a factor. The controlling factor is the underlying block pattern (maximum number of adjacent units and the number of units sharing a common boundary point). When high chromatic numbers are combined with long exclusions periods the results are long rotations and reduced periodic harvests. There is a wide range in the number and timing of harvest entries and the resulting age-class structures that are spatially feasible. This suggests that resource policy makers should think in terms of the desired residual forest structure prior to prescribing harvesting guidelines.

Designing forest plans with conflicting objectives using de Novo programming

Optimization techniques which incorporate multiple objectives and operate within a soft decision environment offer great promise for increasing the utility of forest planning models. Using de novo programming, we illustrate the potential use of designing optimal forest systems in the face of conflicting objectives. A multiple objective linear programming model is used to illustrate this approach. both the generation and evaluation of compromise solutions under de novo conditions are discussed.

The Declining Even Flow Effect and the Process of National Forest Planning

Abstract Recent literature (McQuillan 1986) has identified what may be a serious flaw in the planning process used by the USDA Forest Service. The problem, which McQuillan called the declining even flow effect (DEFE), can occur during repeated iterations of a planning process in cases where a timber harvest scheduling model whose objective is wealth maximization subject to nondeclining yield constraints is utilized. The DEFE creates a situation in a sequence of plans over time in which the first period harvest level declines below that attained for previous planning iterations. This paper addresses the relationship between the process used by the Forest Service to develop FORPLAN models and the DEFE. An example using Kootenai National Forest planning documents is presented to illustrate the highly constrained nature of Forest Service planning models. The effect of these constraints and other characteristics of FORPLAN models on the DEFE is examined. Two items common to nearly all forest planning models, a land base which is not entirely old-growth and constraints to assure that the 40-ac clearcut limit is not violated, caused a large reduction in the DEFE observed in a FORPLAN version of McQuillan's case study model. However, one characteristic of Forest Service planning models, the use of intermediate harvest options, which plausibly could have reduced the DEFE, did not. The major conclusion of the study is that the regulations, initial conditions, and formulation of the FORPLAN model all tend to reduce the likelihood and magnitude of the DEFE. For. Sci. 36(3):665-679.

The Delivery of Semiprimitive Outdoor Recreation Opportunities on the Chattahoochee National Forest and Variations in Timber Demand

Abstract The Chattahoochee Forest Planning Model was modified to include semiprimitive nontimber harvest management prescriptions that equalled the maximum annual production of recreation visitor days of the existing timber harvest prescriptions. The present net value formulation was resolved to determine if the inclusion of the nontimber harvest prescriptions would affect the model's allocation of semiprimitive outdoor recreation resources. The revised model was also subjected to a series of resource allocation sensitivity simulations in which the estimates of future timber demand were varied. The allocation of semiprimitive outdoor recreation resources was influenced by the new prescription only when timber demand was less than 100% of the current timber demand estimate. Actual maximum acreage allocation of semiprimitive resources was achieved when timber demand was 75% of the existing estimate. Doubling the timber demand estimate did not decrease the acres allocated to the semiprimitive resource on the Chattahoochee National Forest. South J. Appl. For. 12(4):246-252

Forest, Regional and Sector Planning Models in New Zealand

The New Zealand forest sector is facing an unprecedented expansion over the next 30 years, due to a radiata pine planting boom during the 1960's and 70's. Markets and processing capacity will have to be expanded to take advantage of the increases in production from exotic plantations, increases predicted to more than triple the current annual cut of about 10 million m3. This paper outlines some of the planning models that are being developed to assist New Zealand's forest sector in coping with its imminent expansion. While these models are a step in the right direction, further work is required in the planning of wood processing and marketing if New Zealand hopes to make the most of its plantation resources. Key words: New Zealand, planning models, radiata pine.

The Declining Even Flow Effect—Non Sequitur of National Forest Planning

Abstract The traditional concept of sustained yield has evolved into the more rigid notion of even flow for timber harvest regulation on national forests. Combination of an even flow constraint with a wealth-maximizing objective function in current formulations of the forest planning model can lead to an anomaly, dubbed the declining even flow effect (DEFE), when the national forest planning process is repeated periodically as required by law. When the effect occurs, first-decade harvests fall during successive planning cycles. The cause lies in both the redefinition of the even flow constraint that occurs at successive planning cycles and the assumptions associated with a capital efficiency objective function that are violated when an even flow constraint is imposed. Forest Sci. 32:960-972.

Timber Management Decision Making under Imperfect Capital Markets

AbstractCapital market imperfections seldom have been considered in the choice of financial criteria for making timber management decisions. A forest planning model for evenaged timber management is developed to evaluate criterion selection under imperfect markets. Some investment rules are shown to be equivalent to maximizing the firm's liquidation value for certain capital market conditions. Although imperfect capital markets severely limit wealth accumulation, small deviations from the optimal harvesting schedules do not severely affect the firm's value. Much concern about criterion selection would evaporate if the firm's investing and financing functions were integrated into a single process.