John Sessions

Using Tabu search to schedule timber harvests subject to spatial wildlife goals for big game

Abstract An algorithm was developed that uses Tabu search to schedule timber harvests subject to even-flow of timber volume harvested, adjacency constraints, and spatial wildlife habitat quality goals. A subroutine within the algorithm senses the size of contiguous cover blocks in order to evaluate the wildlife habitat quality goals. The wildlife habitat quality goals consist of (1) maintaining at least 80% of the forage area within 200 m of a hiding or thermal patch at least 3 ha in size, and (2) maintaining 80% of the forage area within 300 m of a hiding or thermal patch at least 17 ha in size. To illustrate the procedure, feasible harvest plans for a three-period planning horizon were developed. Two scenarios were examined: (1) units 0–39 years old were considered forage, and there was no minimum harvest age for timbered units, and (2) units 0–9 years old were considered forage with a minimum harvest age of 50 years for timbered units. The second wildlife habitat quality goal was found to be the most limiting in both scenarios, while the first wildlife goal was at a minimum for only one of the three periods in the case study. The results of the first scenario showed that the second wildlife goal was at the minimum level for all three periods when the algorithm has reached a steady-state area of locating solutions. The second scenario resulted in a much more spatially and temporally constrained set of results, where all solutions met the wildlife goals, yet a steady state was not reached and harvest levels eventually deviated widely from an even-flow perspective. We demonstrate that an algorithm can be developed to simultaneously evaluate these types of spatial wildlife goals which do not have a predictable response to decision choices.

A review of the challenges and opportunities in estimating above ground forest biomass using tree-level models.

Accurate biomass measurements and analyses are critical components in quantifying carbon stocks and sequestration rates, assessing potential impacts due to climate change, locating bio-energy processing plants, and mapping and planning fuel treatments. To this end, biomass equations will remain a key component of future carbon measurements and estimation. As researchers in biomass and carbon estimation, we review the present scenario of aboveground biomass estimation, focusing particularly on estimation using tree-level models and identify some cautionary points that we believe will improve the accuracy of biomass and carbon estimates to meet societal needs. In addition, we discuss the critical challenges in developing or calibrating tree biomass models and opportunities for improved biomass. Some of the opportunities to improve biomass estimate include integration of taper and other attributes and combining different data sources. Biomass estimation is a complex process, when possible, we should make use of already available resources such as wood density and forest inventory databases. Combining different data-sets for model development and using independent data-sets for model verification will offer opportunities to improve biomass estimation. Focus should also be made on belowground biomass estimation to accurately estimate the full forest contribution to carbon sequestration. In addition, we suggest developing comprehensive biomass estimation methods that account for differences in site and stand density and improve forest biomass modeling and validation at a range of spatial scales.

Using sulfite chemistry for robust bioconversion of Douglas-fir forest residue to bioethanol at high titer and lignosulfonate: a pilot-scale evaluation.

This study demonstrated at the pilot-scale (50 kg) use of Douglas-fir forest harvest residue, an underutilized forest biomass, for the production of high titer and high yield bioethanol using sulfite chemistry without solid-liquor separation and detoxification. Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL) was directly applied to the ground forest harvest residue with no further mechanical size reduction, at a low temperature of 145°C and calcium bisulfite or total SO2 loadings of only 6.5 or 6.6 wt% on oven dry forest residue, respectively. The low temperature pretreatment facilitated high solids fermentation of the un-detoxified pretreated whole slurry. An ethanol yield of 282 L/tonne, equivalent to 70% theoretical, with a titer of 42 g/L was achieved. SPORL solubilized approximately 45% of the wood lignin as directly marketable lignosulfonate with properties equivalent to or better than a commercial lignosulfonate, important to improve the economics of biofuel production.

A Combinatorial Heuristic Approach for Solving Real-Size Machinery Location and Road Design Problems in Forestry Planning

The location and operation of harvest machinery, along with the design and construction of access roads, are important problems faced by forestry planners, making up about 55% of total production costs. One of the main challenges consists of finding a design that will minimize the cost of installation and operation of harvest machinery, road construction, and timber transport, while complying with the technical restrictions that apply to the operation of harvesting equipment and road construction. We can model the network design problem as a mixed-integer linear programming problem. This model is fed with cartographic information, provided by a geographic information system (GIS), along with technical and economic parameters determined by the planner. We developed a specialized heuristic for the problem to obtain solutions that enable harvesting economically profitable volumes at a low cost. This methodology was programmed into a computer system known as PLANEX and is being applied in nine forestry companies that report important benefits from its use.

Preliminary Planning of Road Systems Using Digital Terrain Models

Unlike the traditional way of forest road planning in which the forest engineer manually tries to find alternative routes to access areas scheduled for harvest, a computerized method using data from a digital terrain model is presented. The method identifies feasible road segments, evaluates their variable and fixed cost components and then determines the optimal set of road segments to be used and the year in which the roads are to be constructed.

Economic and Spatial Impacts of an Existing Reserve Network on Future Augmentation

An optimization model for land reservation was developed that explicitly selects parcels in the most compact or contiguous manner possible while meeting habitat requirements and a budget limitation. The model was used to compare the effects of an existing reserve network on future parcel spatial locations and total cost. Using habitat and land value data from Josephine County, Oregon, it was found that a system of existing reserves created by various policies and overseen by different agencies can decrease future reserve compactness and contiguity, and increase total cost. This work suggests that coordinated planning can result in more efficient conservation efforts for less cost.

Application of an airborne laser scanner to forest road design with accurate earthwork volumes

In this study we developed a forest road design program based on a high-resolution digital elevation model (DEM) from a light detection and ranging (LIDAR) system. After a designer has located the intersection points on a horizontal plane, the model first generates the horizontal alignment and the ground profile. The model precisely generates cross-sections and accurately calculates earthwork volumes using a high-resolution DEM. The model then optimizes the vertical alignment based on construction and maintenance costs using a heuristic technique known as tabu search. As the distance between cross-sections affects the accuracy of earthwork volume calculations, the results were examined by comparing them with the exact earthwork volume calculated by the probabilistic Monte Carlo simulation method. The earthwork volumes calculated by the Pappus-based method were similar to those calculated by the Monte Carlo simulation when the distance between cross-sections was within 10 m. The model was applied to a high-resolution DEM from the LIDAR of Capitol Forest in Washington State, USA. The model generated a horizontal alignment, length 827 m, composed of five horizontal curves. We examined the number of grade change points. The results indicated that tabu search found the best solution (

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

61.42/m) with five grade change points. This was composed of two vertical curves that almost followed the ground profile. As the accuracy of a high-resolution DEM from LIDAR increases, the model would become a useful tool for a forest road designer because it eliminates or at least reduces the time-consuming process of road surveys.

Forest road operations in the tropics.

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.

Applying LiDAR technology for tree measurements in burned landscapes

Forest Roads in the Tropics.- Road Standards.- Economic Basis for Forest Road Construction.- Route Selection.- Road Building Materials.- Forest Road Construction.- Crossing Swamps and Wetspots.- Stream Crossings.- Forest Road Maintenance.- Road Equipment and Machinery.- Environmental Protection.- Concluding Comments.