Timber Harvest Volume Research Articles

Multi-objective optimization for timber harvest management incorporating wildlife habitat goals

ContextThe forestry industry provides important goods, services and economic benefits, but timber harvest can adversely impact ecosystem services, including wildlife habitat. Timber harvest planning can integrate wildlife habitat quality through multi-objective optimization for timber harvest and wildlife habitat suitability.ObjectivesOur objective was to develop a method to find optimal solutions for timber harvest and wildlife habitat suitability individually and concurrently, then apply the method to Roosevelt elk (Cervus elaphus roosevelti) on Afognak Island, Alaska.MethodsWe developed three seasonal habitat suitability models using elk locations and landscape variables including historical timber harvest on Afognak Island, Alaska. We used threshold-accepting optimization over a 50-year planning horizon to maximize timber harvest yield and habitat suitability in each season, then used multi-objective goal-deviation optimization to simultaneously maximize timber harvest volume and seasonal habitat suitability.ResultsThe optimal solution for timber yield decreased seasonal average habitat suitability by 5.7%. Elk habitat suitability and corresponding optimal solutions varied seasonally; elk generally selected open landcovers and early- to mid-successional timber stands over late-successional and mature stands. Therefore, in the optimal solutions, stands were harvested before they reached maximum volume and few stands were harvested in early planning periods, resulting in a seasonal average loss of 17.5% yield. Multi-objective optimization decreased seasonal average suitability by 3.9% and yield by 1.4% compared to single-objective optimization.ConclusionsOur multi-objective optimization approach that incorporates data-driven habitat suitability models using open-source software can enable managers to achieve desired quantity and quality of wildlife habitat while providing for resource extraction.

Understanding the impact of interprovincial trade on forest resources in China

Intensified interprovincial trade causes timber flows between regions in China, exacerbating the contradiction between economic development and forest conservation. To understand the impacts of interprovincial trade on forest resource depletion in China, this study developed a timber-extended multiregional input–output model to quantify the virtual timber harvest volume (THV) of each province. A forest stress index (FSI) is also developed to reflect the pressure of forest resource protection in different regions and evaluate the impacts of interprovincial trade on forest stress at national and provincial scales. The results showed that provinces within main forest zones (e.g., Guangxi, Guangdong, and Fujian) presented higher production-based THV than consumption-based THV while the opposite was true for provinces in the rest of the country (ROC) (e.g., Shanghai, Shandong, and Jiangsu). Interprovincial trade in China resulted in 36.86 million m3 of virtual timber flow annually (2008–2017 average), approximately 16.80% of the country's total production-based THV. During the study period, trade activities continuously reduced China's FSI, but ROC provinces mitigated their forest stress at the cost of increasing the burden on provinces in forest zones. Additionally, distant trade tended to have a stronger effect on provincial forest stress compared with trade between adjacent provinces. The findings identified the critical regions and trade routes that directly or indirectly drove forest degradation and revealed the effects of interprovincial trade on forest stress. Furthermore, this study proposed potential policy measures to promote the sustainable management of forest resources in China.

Multi-objective models for the forest harvest scheduling problem in a continuous-time framework

In this study we present several multi-objective models for forest harvest scheduling in forest with single-species, even-aged stands using a continuous formulation. We seek to maximize economic profitability and even-flow of timber harvest volume, both for the first rotation and for the regulated forest. For that, we design new metrics that allow working with continuous decision variables, namely, the harvest time of each stand. Unlike traditional combinatorial formulations, this avoids dividing the planning horizon into periods and simulating alternative management prescriptions before the optimization process. We propose to combine a scalarization technique (weighting method) with a gradient-type algorithm (L-BFGS-B) to obtain the Pareto frontier of the problem, which graphically shows the relationships (trade-offs) between objectives, and helps the decision makers to choose a suitable weighting for each objective. We compare this approach with the widely used in forestry multi-objective evolutionary algorithm NSGA-II. We analyze the model in a Eucalyptus globulus Labill. forest of Galicia (NW Spain). The continuous formulation proves robust in forests with different structures and provides better results than the traditional combinatorial approach. For problem solving, our proposal shows a clear advantage over the evolutionary algorithm in terms of computational time (efficiency), being of the order of 65 times faster for both continuous and discrete formulations.

A Survey of Forestry Extension Clientele in South Carolina, USA

The U.S. South contains nearly one-third of the nation’s forests and 40% of its productive timberland. This makes the southern U.S. an important part of the wood supply chain. In South Carolina, family forests cover 55% of the 13 million acres of forestland, and contribute significantly to the annual timber harvest volume. However, not all family forest owners are engaged in forest management activities. To better understand the needs and behaviors of family forest owners that are actively engaged in forest management an online survey was developed and sent to family forest owners that actively seek the help of extension agents. Results of a latent-class analysis of survey responses showed that there are three distinct groups of family forest owners that engage with extension agents: hands-on timber managers, hands-off timber managers, and multiple-use land managers. These groups differ in their utilization of help from a consulting forester and their ways of selecting timber harvesting contractors for forest management activities. Eighty-eight percent of respondents reported that their major goal of a thinning was to maximize future revenues. When asked about the expected outcome of a cleat-cut, 69% expected all trees to be removed, whereas the rest expected outcomes similar to selection, seed-tree, or commercial clear-cuts. Overall, this survey provides initial information to better focus outreach and extension efforts, but also highlights how family forest owners engage in their timber harvest.

Salvage logging following fires can minimize boreal caribou habitat loss while maintaining forest quotas: An example of compensatory cumulative effects

Protected area networks are the dominant conservation approach that is used worldwide for protecting biodiversity. Conservation planning in managed forests, however, presents challenges when endangered species use old-growth forests targeted by the forest industry for timber supply. In many ecosystems, this challenge is further complicated by the occurrence of natural disturbance events that disrupt forest attributes at multiple scales. Using spatially explicit landscape simulation experiments, we gather insights into how these large scale, multifaceted processes (fire risk, timber harvesting and the amount of protected area) influenced both the persistence of the threatened boreal caribou and the level of timber supply in the boreal forest of eastern Canada. Our result showed that failure to account explicitly and a priori for fire risk in the calculation of timber supply led to an overestimation of timber harvest volume, which in turn led to rates of cumulative disturbances that threatened both the long-term persistence of boreal caribou and the sustainability of the timber supply itself. Salvage logging, however, allowed some compensatory cumulative effects. It minimised the reductions of timber supply within a range of ∼10% while reducing the negative impact of cumulative disturbances caused by fire and logging on caribou. With the global increase of the human footprint on forest ecosystems, our approach and results provide useful tools and insights for managers to resolve what often appear as lose–lose situation between the persistence of species at risk and timber harvest in other forest ecosystems. These tools contribute to bridge the gap between conservation and forest management, two disciplines that remain too often disconnected in practice.

Land‐use impacts on the quantity and configuration of ecosystem service provisioning in Massachusetts, USA

Summary Meeting fundamental human needs while also maintaining ecosystem function and services is the central challenge of sustainability science. In the densely populated state of Massachusetts, USA, abundant forests and other natural land cover convey a range of ecosystem services. However, after more than a century of reforestation following an agrarian past, Massachusetts is again losing forests, this time to housing and commercial development. We used land‐cover maps, ecosystem process models and land‐use data bases to map changes (2001, 2006, 2011) in eight ecosystem service variables and to identify ‘hotspots’, or areas that produce a high value of five or more services, at three policy‐relevant spatial scales. Water‐related services (clean water provisioning and flood regulation) experienced local declines in response to shifting land uses, but changed little when measured at the state level. General habitat quality for terrestrial species declined statewide during the study period as a consequence of forest loss. In contrast, climate regulation (carbon storage) and cultural services (outdoor recreation) increased, driven by continued forest biomass accrual and land protection, respectively. Timber harvest volume had high interannual variability, but no temporal trend. The scale at which hotspots are delineated greatly affects their quantity and spatial configuration, with a higher density in eastern Massachusetts and 10–12% more hotspots overall when they are identified at a town scale as compared to a watershed or state scale. Synthesis and applications. Ecosystem service hotspots cover a small percentage of land area in Massachusetts (2·5–3·5% of the state), but are becoming more abundant as urbanization concentrates ecosystem service provisioning onto a diminished natural land base. This suggests that while ecosystem service hotspots are valuable targets for conservation, more are not necessarily better since hotspot proliferation can reflect the bifurcation of the landscape into service and non‐service provisioning areas and subsequent loss of diversity across the landscape.

A Dynamic Programming Model to Determine the Optimal Harvest Decision for a Fir Forest that Provides Both Timber Harvest Volume and Carbon Sequestration Services

Carbon sequestration in forests is being considered as a mechanism to slow or reverse the trend of increasing concentrations of carbon dioxide in the atmosphere. We present results to determine the optimal harvest decision for a forest stand in the fir forest of Turkey that provides both timber harvest volume and carbon sequestration services by using a dynamic programming model. The state of the system at any point in time is described by stand age and the amount of carbon in the dead organic matter pool. Merchantable timber volume and biomass are predicted as a function of stand age. As a result of decay and litterfall, carbon stocks in the dead organic matter pool changes. The results of the study indicate that initial carbon stock levels significantly affect economic returns to carbon management while optimal harvest age is relatively insensitive to carbon stocks in dead organic matter.

Landscape-level optimization using tabu search and stand density-related forest management prescriptions

Spatial and temporal scheduling of forest management activities is becoming increasingly important due to recent developments in environmental regulations, goals and policies. A forest planning model was developed to select activities for stands in a forested area (178,000 ha), from a set of stand-centric optimal prescriptions, to best meet a higher-level landscape objective. The forest-level management problem addressed is complex, if not impossible to solve optimally, with current computing technologies, as integer decision variables are assumed. The higher-level landscape objective is to achieve the highest even-flow of timber harvest volume. Three types of tabu search processes were examined in the model: (1) a process with 1-opt moves only; (2) a process with 1-opt moves and a region-limited 2-opt move process; and (3) a process with 1-opt moves and 10 iterations through a smaller region-limited 2-opt move process. Aspiration criteria and short-term memory were employed within tabu search in an attempt to avoid becoming trapped in local optima. While the 1-opt move process alone created solutions (forest plans) that were adequate, and contained higher average harvest volumes than the other methods, the addition of the 2-opt move processes improved the solutions generated by intensifying the search around local optima. The solutions produced using the 2-opt move processes had less variation in periodic harvest volumes across the planning horizon. While the basic 1-opt tabu search process provides adequate feasible solutions to large, complex forest planning problems, we reinforce the notion suggested, but not proven with previous research, that 2-opt neighborhoods can help improve quality of large scale forest plans generated by tabu search. The contribution of this research is the description of a process which be developed for large forest planning problems (the problem examined is at least 1 order of magnitude greater than previous research, in terms of forested stands modeled), a process that could enable one to produce more efficient forest planning solutions than one could otherwise with standard 1-opt tabu search. In addition, we describe here the use of a set of optimal stand-level prescriptions to choose from when utilizing the 2-opt process, rather than a set of clearcut periods to consider. With this in mind, this research represents a fundamentally new application of operations research techniques to realistic forest planning problems.

Divided landbase, overlapping tenures, and fire risk

The Tardis forest modeling program was used to investigate the effects on timber supply and delivered wood cost of alternative forest tenure policies on a forest management agreement area in northeastern Alberta. Under the current tenure policy (business as usual), the woodlands divisions of one large pulp company and several sawmill companies are responsible for different aspects of planning and forest management on the area. We propose an alternative tenure policy (global planning) whereby one forest management entity is responsible for harvesting timber and delivering it to the various mills. The global planning alternative has several advantages over business as usual, especially for the sawmill companies. With business as usual, the sawmill companies experience shortfalls in timber harvest volume. No shortfall is seen with global planning. Under global planning, delivered wood cost for the sawmill companies is reduced by $2.81 m–3 , on average. Forest fire is an important disturbance affecting timber supply in the area. We examine the joint effects of tenure policy and fire using Monte Carlo simulation. The superiority of global planning is even more apparent with fire incorporated in the model. According to our simulations, many sawmills are very likely to experience persistent sharp decreases in delivered wood volume under business as usual. No such decreases occur under global planning. Key words: forest tenure, simulation modeling, timber harvest scheduling, forest fire, policy analysis, boreal mixedwood, sustainable forest management

A Model and Tabu Search Method to Optimize Stand Harvest and Road Construction Schedules

Abstract An important function of tactical planning in forest management is to choose spatially and temporally explicit schedules for both harvesting and road construction activities. In addition to maintaining consistency with goals of the strategic planning process, harvesting decisions are subjected to spatial, environmental constraints. At the same time, planning and cost of road access over the medium-term planning horizon must be considered.This article presents a model and heuristic solution methodology to address stand level harvest scheduling and the associated road construction scheduling problem. The model is formulated to determine minimal cost schedules, for stand harvests and road construction, that achieve recommended timber harvest volume targets and that comply with environmental regulations. The harvest decisions are made at the stand level of resolution. Graph structures are used to formulate the spatial restrictions on clearcut opening size and location. Road construction projects are scheduled to create a feasible road network at minimum net present capital cost.The optimization problem is solved using a Tabu search heuristic, which includes special constructs to cope with the complexity of this problem. An efficient frontier of solutions is produced, which may be utilized to analyze tradeoffs between lost forest productivity, due to timing of harvests, and the capital cost of road construction. Forest Science 46(2):188-203.

Combinatorial optimization of elk habitat effectiveness and timber harvest volume

Forest resource planning processes in the western United States have been placing an increasing emphasis on wildlife and fish habitat goals. With this in mind, we developed a method that incorporates a Habitat Effectiveness Index (HEI) for Roosevelt elk (Cervus elaphus roosevelti) into the objective function of a mathematical forest planning model. In addition, a commodity production goal is proposed (maximum timber production), and the habitat and commodity production goals are allowed to act as goals in a multi-objective goal programming planning problem. A heuristic programming technique (tabu search) is used to develop feasible solutions to the resulting non-linear, integer programming problem. Using a hypothetical example, we illustrate results of five scenarios, where the emphasis of the achievement of one or both goals is altered. The main contribution of this approach is the ability to measure and evaluate the trade-offs among achieving a certain level of a complex wildlife goal and achieving commodity production goals. These trade-offs are measured using a flexible model, allowing planners to formulate non-linear spatial goals as objectives of a problem, rather than forcing them to rely on posterior evaluations of the suitability of management plans to goals such as elk HEI.

IMPROVING AQUATIC HABITAT CONDITIONS OVER TIME WHILE PRODUCING WOOD PRODUCTS: AN EXAMINATION OF OPTIONS1

ABSTRACT: A land management activity scheduling model that can perform a multi‐period, simultaneous evaluation of aquatic habitat quality and commodity production goals was used to identify alternatives which would allow the improvement of aquatic habitat conditions over time, while producing wood products. The scheduling model has the ability to use stream sediment index levels, stream temperature index levels, and equivalent clearcut acres (ECA) levels as primary goals. A secondary goal imbedded in the model is the achievement of an even‐flow of timber harvest volume, and a tertiary goal is the achievement of maximum efficiency (maximum net present value). The scheduling model utilizes a heuristic programming technique (Tabu search) to guide the selection of timber harvests and road standards. A 14,643 acre case study watershed in eastern Oregon is used to illustrate several policy scenarios. Activities considered include: clearcutting and partial cutting; cable, skyline, ground‐based, and helicopter logging; road obliteration; requiring lower truck tire pressures on forest roads; and tree planting in riparian areas. The scheduling model produced land management plans which were spatially and temporally feasible over ten ten‐year time periods. Stream temperature was shown to be dramatically reduced if tree planting is performed in all riparian areas, regardless of whether harvesting activities occurred, and including meadows and forested areas where shade density is low. Timber harvest volume levels decreased 31 to 43 percent, and net present value levels decreased 36 to 46 percent, from an unconstrained case, when any of the following occurred: ECA was constrained to 15 percent, sediment index levels were required to decrease by 1 percent per decade, or temperature levels were constrained to “no harvest” levels. The use of a heuristic programming technique is a departure from traditional techniques that are commonly used in management plan development. Yet the heuristic technique allows the inclusion of complex management goals, many of which may be prohibited when using more traditional mathematical programming techniques. In addition, decision variables which require spatial information, requiring them to take on integer or non‐linear representations, can be accounted for without realizing the limitations of the traditional techniques.