Magazine article Endangered Species Update

An Optimization Model to Select Redwood Stands for the Conservation of the Marbled Murrelet in the Headwaters Forest HCP

Magazine article Endangered Species Update

An Optimization Model to Select Redwood Stands for the Conservation of the Marbled Murrelet in the Headwaters Forest HCP

Article excerpt

Abstract

This work describes an explicit method by which alternative stand selection scenarios concerning the threatened marbled murrelet (Brachyramphus marmoratus) in the Headwaters Forest Habitat Conservation Plan were generated and evaluated. Preservation goals and timber harvesting goals are simultaneously considered. An integer programming model (classical 1,0 knapsack problem) is applied to identify sets of redwood groves that optimized marbled murrelet nesting habitat value for given values of foregone timber production. Alternatively, the results can be interpreted as minimizing applicant cost for given levels of murrelet habitat value. The outcome of the analysis does not show that a small number of very high quality selections would reserve most of the available murrelet habitat. Instead, the analysis supports the contention that the more old-growth that can be reserved, the better the measures of nesting habitat become. Ultimately, the results of this analysis were not used for negotiating the final Headwaters Forest Habitat Conservation Plan. However, the grove selection optimization model is valuable in that it provides a general method for balancing habitat value and economic value.

Introduction

The Headwaters Forest in northern coastal California is infamous for one of the premiere conservation battles of the 1990s. The contention is over the preservation of old-growth forest, especially redwood habitat. Listed species that are affected include the northern spotted owl (Strix occidentalis caurina), coho salmon (Oncorhynchus kisutch), and marbled murrelet (Brachyramphus marmoratus). This paper focuses on a decision aid that was applied during the negotiations over the amount of private timberland that would be set aside as nesting habitat for the marbled murrelet.

The best-known conservation activities in the Headwaters were associated with the government purchase of a 7,500-acre tract of old-growth redwoods. Lesser known was the development of a Habitat Conservation Plan (HCP) that is a 50-year agreement between the U.S. Government and Pacific Lumber Company (PL) governing activities on approximately 200,000 acres that are owned privately by PL. The decision model described herein was applied in the context of the HCP.

The marbled murrelet is a seabird that forages in marine coastal areas and is dependent for nesting on the large branches found on old-growth trees such as redwood and Douglas-fir (Naslund 1993; McCarthy 1993). In California, redwood-dominated stands relatively near the coast are considered to be of prime importance (Hunter et al. 1998). The severe loss of old-growth forest habitat has reduced populations in California, Oregon, and Washington to such an extent that the marbled murrelet (for those states) was listed as federally threatened in 1992 (USFWS 1992). A difficult conflict inevitably arises from the marbled murrelet's dependence on old-growth redwood trees for successful nesting and reproduction. Because of the high economic value of such forests for timber harvest, habitat reserves are potentially very costly for a company such as PL. The result is a direct conflict between species protection and economic hardship imposed on a private rights holder. The HCP has to balance both interests. This study uses data developed during the HCP negotiations in the late 1990s to identify "optimal" alternatives that achieve the greatest habitat protection for a given amount of timber volume set aside for conservation. Not just a single solution is created. By varying the limit on foregone harvest, a set of points representing an optimal tradeoff curve between marbled murrelet habitat value and applicant cost can be generated.

Data

Of the 200,000 acres of PL property covered by the HCP, fewer than 10,000 acres remained that were considered to be prime habitat for murrelet nesting. At the time (late 1997), these potential reserved groves were delineated as 23 different stands (Table 1). …

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