Sándor F. Tóth

Dynamic Reserve Selection: Optimal Land Retention with Land-Price Feedbacks

Urban growth compromises open space and ecosystem functions. To mitigate the negative effects, some agencies use reserve selection models to identify conservation sites for purchase or retention. Existing models assume that conservation has no impact on nearby land prices. We propose a new integer program that relaxes this assumption via adaptive cost coefficients. Our model accounts for the two key land price feedbacks that arise in markets where conservation competes with development: the amenity premium and price increases driven by shifts in market equilibriums. We illustrate the mechanics of the proposed model in a real land retention context. The results suggest that in competitive land markets, the optimal conservation strategy during the initial phase of the retention effort might be to use available dollars to buy fewer parcels with smaller total area that are under high risk of development. We show that failure to capture the land-price feedbacks can lead to significant losses in biological conservation. The present study is the first to create a reserve selection model that captures the economic theory of competitive land markets in a dynamic framework, produces tangible, parcel-level conservation recommendations, and works on problems with thousands of potential site selection decisions and several planning periods.

A cutting plane method for solving harvest scheduling models with area restrictions

We describe a cutting plane algorithm for an integer programming problem that arises in forest harvest scheduling. Spatial harvest scheduling models optimize the binary decisions of cutting or not cutting forest management units in different time period subject to logistical, economic and environmental restrictions. One of the most common constraints requires that the contiguous size of harvest openings (i.e., clear-cuts) cannot exceed an area threshold in any given time period or over a set of periods called green-up. These so-called adjacency or green-up constraints make the harvest scheduling problem combinatorial in nature and very hard to solve. Our proposed cutting plane algorithm starts with a model without area restrictions and adds constraints only if a violation occurs during optimization. Since violations are less likely if the threshold area is large, the number of constraints is kept to a minimum. The utility of the approach is illustrated by an application, where the landowner needs to assess the cost of forest certification that involves clear-cut size restrictions stricter than what is required by law. We run empirical tests and find that the new method performs best when existing models fail: when the number of units is high or the allowable clear-cut size is large relative to average unit size. Since this scenario is the norm rather than the exception in forestry, we suggest that timber industries would greatly benefit from the method. In conclusion, we describe a series of potential applications beyond forestry.

Spatially explicit forest harvest scheduling with difference equations

Spatially explicit harvest scheduling models optimize the layout of harvest treatments to best meet management objectives such as revenue maximization subject to a variety of economic and environmental constraints. A few exceptions aside, the mixed-integer programming core of every exact model in the literature requires one decision variable for every applicable prescription for a management unit. The only alternative to this “brute-force” method has been a network approach that tracks the management pathways of each unit over time via four sets of binary variables. Named after their linear programming-based aspatial predecessors, Models I and II, along with Model III, which has no spatial implementation, each of these models rely on static volume and revenue coefficients that must be calculated pre-optimization. We propose a fundamentally different approach that defines stand volumes and revenues as variables and uses difference equations and Boolean algebra to transition forest units from one planning period to the next. We show via three sets of computational experiments that the new model is a computationally promising alternative to Models I and II.

Combining spatiotemporal corridor design for reindeer migration with harvest scheduling in Northern Sweden

ABSTRACT Reindeer husbandry and commercial forestry seek to co-exist in the forests of Northern Sweden. As interwoven as the two industries are, conflicts have arisen. Forest practices have reduced the distribution of lichen, the main winter diet for reindeer. Forest practices have also increased forest density, compromising the animals’ ability to pass through forested areas on their migration routes. In an attempt to reduce impacts on reindeer husbandry, we present a spatially explicit harvest scheduling model that includes reindeer corridors with user-defined spatial characteristics. We illustrate the model in a case study and explore the relationship between timber revenues and the selection and maintenance of reindeer corridors. The corridors are not only to include sufficient lichen habitat, but they are also supposed to ensure access for reindeer by connecting lichen areas with linkages that allow unobstructed travel. Since harvest scheduling occurs over a planning horizon, the spatial configuration of corridors can change from one time period to the next in order to accommodate harvesting activities. Our results suggest that maintaining reindeer corridors in harvest scheduling can be done at minimal cost. Also, we conclude that including corridor constraints in the harvest scheduling model is critical to guarantee connectivity of reindeer pastures.

Forest Harvest Scheduling with Endogenous Road Costs

The Washington State Department of Natural Resources (DNR) manages over 800,000 hectares of forested state trust lands and 20,000 kilometers of forest roads in Washington State. Forest harvest and road reconstruction decisions greatly impact the agency’s cash flows and its ability to meet its fiduciary obligations. We introduce a mixed-integer programming model that integrates harvest and road scheduling decisions. We show how DNR embedded the new model in its workflows and applied it to the Upper Clearwater River Landscape in the Olympic Experimental State Forest. We find that the forest valuation of the Upper Clearwater increased by

Auctioning the Forest: A Qualitative Approach to Exploring Stakeholder Responses to Bidding on Forest Ecosystem Services

0.5–

A model for managing edge effects in harvest scheduling using spatial optimization

1 million (0.4–1.1 percent) because of the new method, which allowed the DNR to concentrate capital expenditures in support of harvest and road operations in both time and space. This led to a 14.5 percent reduction in the size of the active road network. DNR is now in the process of scaling the new approach to the entire forest estate.

Optimizing the Geometry of Wildlife Corridors in Conservation Reserve Design

The loss of private forestland diminishes ecosystems, including wildlife habitat, carbon sequestration and clean water. The emergence of new markets for forest ecosystem services offers one solution for private forestland financing while having the potential to increase the provision of forest ecosystem services. The general public’s willingness to participate in an auction mechanism for private forest ecosystem services was assessed for a regionally representative forest in Washington State using focus group methodology. The auction mechanism utilizes cost-effective management scenarios that stakeholders competitively bid on. Participants exhibited preferences for specific management plans while also making trade-offs in order to ensure that a plan would win. Participants expressed clear preferences for recreational access, mature forest habitat, aesthetic amenities, and improved water quality. Participants were receptive to the auction mechanism while maintaining concerns over viability, transparency, and local stakeholder involvement.

Promoting Large, Compact Mature Forest Patches in Harvest Scheduling Models

ABSTRACT Actively managed forest stands can create new forest edges. If left unchecked over time and across space, forest operations such as clear-cuts can create complex networks of forest edges. Newly created edges alter the landscape and can affect many environmental factors. These altered environmental factors have a variety of impacts on forest growth and structure and can alter harvest yields and habitat for wildlife. For example, chances of windthrow and regeneration shading can increase, which in turn can reduce the expected yield of merchantable timber. Additionally, forest edges can compromise interior forest habitat for wildlife and expose sensitive species to harmful processes such as nest predation or parasitism. We introduce a harvest-scheduling model that can keep track of and control the spatiotemporal development of forest edges. This allows the forest resource analyst to put constraints on edge production in an attempt to meet a variety of production and sustainability objectives. To demonstrate the model’s functionality and tractability, we apply it to a case study in the Pacific Northwest region of the United States.

Finding efficient harvest schedules under three conflicting objectives.

Wildlife corridors are often used to connect critical habitat for species protection. Mixed integer programming models have been used in the past to create wildlife corridors, but they lack the cap...