Woodam Chung

Forest road network design using a trade-off analysis between skidding and road construction costs

Designing forest road networks in a large forest land is a challenging task because many feasible alternatives exist and need to be analyzed. To provide field managers with an analytical tool that can create and analyze alternative road networks, we have developed a road network optimization model. The model formulates a large network problem in which links represent two timber transportation options from evenly distributed timber locations: on-road transportation via new roads and off-road transportation using skidders. A heuristic network algorithm is employed to solve the network problem and identify cost-efficient road networks for timber harvesting under given cost parameters. To demonstrate our model, we applied it to a 4760 ha forest in the upper part of the Mica Creek watershed in Idaho owned by Potlatch Forest Holdings, Inc. The sensitivity analyses were conducted to verify the model’s performance under various cost and volume settings. The model-generated road network was compared with a road ne...

An Application of a Heuristic Network Algorithm to Cable Logging Layout Design

Abstract This paper describes a method for optimizing cable logging layouts using a heuristic network algorithm. A timber harvest unit layout is formulated as a network problem. Each grid cell containing timber volume to be harvested is identified as an individual entry node of the network. Mill locations or proposed timber exit locations are identified as destinations. Each origin will then be connected to one of the destinations through alternative links representing alternative cable corridors, harvesting equipment, landing locations, and truck road segments. A heuristic algorithm for network programming is used to solve the cost minimization network problem. A computerized model has been developed to implement the method. Logging feasibility and cost analysis modules are included in the model in order to evaluate the logging feasibility of alternative cable corridors and estimate yarding and transportation costs. The model was successfully applied to a harvest planning area to generate harvesting plans. This case study indicates that the planning method is best used for pre-planning since modeling assumptions with respect to tail spar availability and unconstrained road alignments may require modification of the plan before implementation.

A productivity and cost comparison of two systems for producing biomass fuel from roadside forest treatment residues.

Abstract Forest operations generate large quantities of forest biomass residues that can be used for production of bioenergy and bioproducts. However, a significant portion of recoverable residues are inaccessible to large chip vans, making use financially infeasible. New production systems must be developed to increase productivity and reduce costs to facilitate use of these materials. We present a comparison of two alternative systems to produce biomass fuel (i.e., “hog fuel”) from forest residues that are inaccessible to chip vans: (1) forwarding residues in fifth-wheel end-dump trailers to a concentration yard, where they can be stored and then ground directly into chip vans, and (2) grinding residues on the treatment unit and forwarding the hog fuel in high-sided dump trucks to a concentration yard, where it can be stored and then reloaded into chip vans using a front-end loader. To quantify the productivity and costs of these systems, work study data were collected for both systems on the same treat...

NETWORK 2000, a Program for Optimizing Large Fixed and Variable Cost Transportation Problems

A computer program, NETWORK 2000, was developed for optimizing variable and fixed cost, multiple period transportation problems. NETWORK 2000 provides users with three different heuristic algorithms for solving various transportation problems. The algorithms include one based on standard shortest path techniques, and two probabilistic algorithms, simulated annealing and great deluge. Each algorithm has an intelligent rule for neighborhood search. This paper presents the algorithms with an example that solves for the minimum cost of road construction and transport given alternative routes and bounds on links.

Applying ant colony optimization metaheuristic to solve forest transportation planning problems with side constraints

Forest transportation planning problems (FTPP) have evolved from considering only the financial aspects of timber management to more holistic problems that also consider the environmental impacts of roads. These additional re- quirements have introduced side constraints, making FTPP larger and more complex. Mixed-integer programming (MIP) has been used to solve FTPP, but its application has been limited by the difficulty of solving large, real-world problems within a reasonable time. To overcome this limitation of MIP, we applied the ant colony optimization (ACO) metaheuristic to develop an ACO-based heuristic algorithm that efficiently solves large and complex forest transportation problems with side constraints. Three hypothetical FTPP were created to test the performance of the ACO algorithm. The environmental impact of forest roads represented by sediment yields was incorporated into the economic analysis of roads as a side con- straint. Four different levels of sediment constraints were analyzed for each problem. The solutions from the ACO algo- rithm were compared with those obtained from a commercially available MIP solver. The ACO solutions were equal to or slightly worse than the MIP solution, but the ACO algorithm took only a fraction of the computation time that was re- quired by the MIP solver.

Optimising fuel treatments over time and space

Fuel treatments have been widely used as a tool to reduce catastrophic wildland fire risks in many forests around the world. However, it is a challenging task for forest managers to prioritise where, when and how to implement fuel treatments across a large forest landscape. In this study, an optimisation model was developed for long-term fuel management decisions at a landscape scale. Using a simulated annealing algorithm, the model optimises locations and timingoffueltreatments,whileconsideringchangesinforestdynamicsovertime,firebehaviourandspread,valuesatrisk, and operational feasibility. The model employs the Minimum Travel Time algorithm in FlamMap and the Fire and Fuels Extension to the Forest Vegetation Simulator to assess spatial and temporal effects with and without fuel treatments. The objectivefunctionissettominimisetotalexpectedlossfromalandscapeduetowildfiresthroughouttheplanninghorizon. The model was applied to a 14000-ha study landscape located on the west side of the Bitterroot Valley in Montana. Comparisons between the optimised and random solutions show that the model was able to strategically locate and schedule fuel treatments to efficiently reduce expected loss from the landscape. Additionalkeywords: firebehaviour,fuelsreduction,heuristicoptimisation,minimisingexpectedloss,minimumtravel time.

Eight Heuristic Planning Techniques Applied to Three Increasingly Difficult Wildlife Planning Problems: A Summary

Forest planning goals are becoming increasing complex, as both spatial and temporal characteristics of desired future conditions are becoming important measures of forest plan success. Eight types of heuristic planning techniques were applied to three increasingly difficult forest planning problems where the objective function sought to maximize the amount of land in certain types of wildlife habitat. The eight heuristic techniques were random search, simulated annealing, great deluge, threshold accepting, tabu search with 1-opt moves, tabu search with 1-opt and 2-opt moves, genetic algorithm, and a hybrid tabu search / genetic algorithm search process. Three classes of techniques were determined: very good (simulated annealing, threshold accepting, great deluge, tabu search with 1-opt and 2-opt moves, and tabu search / genetic algorithm), adequate (tabu search with 1-opt moves, genetic algorithm), and less than adequate (random search). The data sets are available on the WEB.

Optimizing Fuel Treatments to Reduce Wildland Fire Risk

Fuel treatments have been widely used as an effective fire management tool to mitigate catastrophic wildland fire risk in forested landscapes. Fire research efforts of the last two decades have significantly advanced fire behavior modeling and fuel treatment effects analysis, but integrated fuel treatment planning and optimization models have yet to be extensively developed and used, mainly due to the complexity of the planning problem. This paper describes the problem complexity in terms of essential considerations when deciding where, when, and how to perform fuel treatments. Previous studies published in mainstream peer-reviewed journals are summarized and identified by their unique contributions, assumptions, and simplifications. Only a handful studies assessed fuel treatment effects in spatial and temporal contexts and incorporated them into the optimization framework. Most of these existing studies introduced optimization approaches as proof of concept with limited applications. It is hoped that future studies will build on these previous efforts and develop more efficient and integrated optimization approaches that can address multiple concerns simultaneously while producing effective fuel treatment plans for field implementation.

Financial Performance of a Mobile Pyrolysis System Used to Produce Biochar from Sawmill Residues

Abstract Primary wood products manufacturers generate significant amounts of woody biomass residues that can be used as feedstocks for distributed-scale thermochemical conversion systems that produce valuable bioenergy and bioproducts. However, private investment in these technologies is driven primarily by financial performance, which is often unknown for new technologies with limited industrial deployment. In this paper, we use shift-level production data collected during a 25-day field study to characterize the conversion rate and system productivity and costs for a commercially available pyrolysis system co-located at a sawmill, and then evaluate the net present value (NPV) of the operation in light of a cost structure that is realistic for the industry. Baseline costs on a feedstock throughput basis were estimated as

The effects of site factors on herb species diversity in Kwangneung forest stands

16.41 t−1 for feedstock preparation,