Ecology and Management of Giant Sequoia Groves

NATHAN L. STEPHENSON National Biological Service Sequoia and Kings Canyon National Parks Three Rivers, California 55 Ecology and Management of Giant Sequoia Groves ABSTRACT Present conditions in many sequoia groves demand immediate attention—particularly the ongoing failure of giant sequoia regenera- As a result of recent changes in U.S. Forest Service (USFS) policy, tion and the accumulation of hazardous fuels. Yet our present under- the two public agencies that collectively manage most giant sequoia standing of grove restoration and conservation is imperfect, meaning groves—the USFS and the National Park Service—now share re- that management must move forward in spite of uncertainties. Suc- markably similar sequoia management goals: to protect, restore, and cess therefore depends on managers practicing adaptive manage- conserve giant sequoia ecosystems for their non-commodity values. ment, which formalizes the common-sense process of trying The goal of greatest immediate importance is to protect sequoia something, seeing what happens, learning from the experience, then groves from unusually severe wildfires; the hazard of such fires has trying something new. Successful adaptive management depends increased with the accumulation of forest fuels during a century of on monitoring the results of different management actions, a step fire exclusion. By reducing surface fuels, tree density, and the verti- that is often ignored. Within certain bounds, there is no single clearly cal continuity of aerial fuels, restoration of pre-Euroamerican grove correct approach to grove restoration and conservation; thus, the conditions automatically confers a good deal of protection from ex- different sequoia management agencies are likely to apply a variety treme wildfires. Managers wishing to restore pre-Euroamerican grove of different management approaches. Knowledge will grow most rap- conditions face at least four complex issues: (1) defining specific res- idly if the various agencies cooperate in comparing the consequences toration goals (e.g. is the goal simply to restore low- to moderate- of their different management approaches. intensity fire as a natural process, letting it determine forest structure, For the agencies managing giant sequoias, meeting obligations or to mechanically restore a particular forest structure before reintro- to protect, restore, and conserve sequoia ecosystems will be diffi- ducing fire?), (2) describing the physical targets for restoration (what cult, time-consuming, and expensive. Efforts seem sure to fail un- was the range of pre-Euroamerican grove conditions?), (3) evaluat- less there is strong institutional support at all levels, including ing the practicality and possibility of re-creating the target grove con- significant permanent base funding. ditions (can we restore past conditions, given the limitations imposed by present grove conditions?), and (4) choosing specific restoration tools and approaches (what are the trade-offs among using prescribed fire, saws, or both as restoration tools?). Once groves have been protected and restored a conservative INTRODUCTION approach to assuring their long-term sustainability is to maintain the processes that sustained them in the past, especially frequent low- The charge of the Sierra Nevada Ecosystem Project (SNEP) to moderate-intensity surface fires. Undisturbed hydrology is also included conducting “[a]n examination of the Mediated Settle- important, thus special management attention should focus on the ment Agreement [U.S. Forest Service 1990], Section B, Sequoia local watershed above and adjacent to groves. There is no evidence Groves for the Sequoia National Forest and recommendations that the long-term sustainability of giant sequoia ecosystems as a for scientifically based mapping and management of Sequoia whole depends on adding to the public land base. Continuing and groves” (SNEP 1994). This chapter is limited to addressing future threats to sequoia ecosystems include air pollution, unnatural the last part of this charge: providing an assessment for sci- effects of pathogens, and anthropogenic climatic change. entifically-based management of sequoia groves, with some Sierra Nevada Ecosystem Project: Final report to Congress, vol. II, Assessments and scientific basis for management options. Davis: University of California, Centers for Water and Wildland Resources, 1996. 1431 1432 VOLUME II, CHAPTER 55 attention given to scientifically-based grove mapping. The re- dous social value placed on individual large sequoias, such as mainder of the SNEP charge relating to giant sequoias (i.e., when prescribed fire has charred the trunks of some sequoias examining the Mediated Settlement Agreement between Se- (Croft 1994; Parsons 1994; Tweed 1994). However, managing quoia National Forest and various appellants, and related whole sequoia ecosystems and managing selected individual institutional issues) is addressed by Elliott-Fisk et al. (1996). sequoias as objects of great social importance are not mutually To a large degree, this chapter is shaped by three premises. exclusive, and the analysis I present here should not be taken The first is that sequoia management policy, at its broadest, is to preclude the special status of selected big trees. Rather, man- an ethical decision reflecting human values (Croft 1994); the aging whole sequoia ecosystems should be viewed as a con- role of science is to inform and support the expression of those servative approach to maintaining the sequoias themselves, values. This chapter accepts as a given that the management assuring their perpetuation for the enjoyment and benefit of goal for the majority of naturally-occurring sequoia groves, future generations. as determined by decades of public and political discourse, is Even though the overarching goal of sequoia grove man- to protect, restore, and conserve the natural character of the agement is to sustain all the pieces of giant sequoia ecosys- groves (see “Broad Goals of Sequoia Management,” below). tems, this chapter focuses almost exclusively on trees. This is Science’s most important role in sequoia management is to because (1) social values are such that most past management suggest different means to achieve this end, and to evaluate conflicts have centered on trees, (2) trees are the components their possible consequences. This chapter therefore musters of sequoia ecosystems for which the best available scientific the best available scientific information to support a critical information is available, and (3) through their dominant in- review and analysis of the complex policy, scientific, and prac- fluence on habitat structure, microclimate, and soil proper- tical issues related to the protection, restoration, and conser- ties, trees exert tremendous influence on most other organisms vation of giant sequoia ecosystems for their amenity values. within sequoia ecosystems. A handful of sequoia groves, both public and private, cur- The remainder of the chapter is divided into six sections. rently are managed for commodity production in addition to The first summarizes present conditions in giant sequoia amenity values (e.g. see Dulitz 1986; Rueger 1994); however, groves throughout the Sierra Nevada, and is followed by a a review of issues related to commodity production is beyond brief section summarizing the new, broad sequoia manage- the scope of this chapter. ment goals adopted by the USFS. The next three sections se- The second premise is that forest managers, policy-mak- quentially assess sequoia grove protection, restoration, and ers, and the public will best be served by a chapter that fo- conservation. By far most attention is given to the complex cuses on broad principles of sequoia ecology and management, and difficult task of defining specific grove restoration goals not on site-specific management prescriptions or in-depth dis- and describing targets for restoration; of necessity, new syn- cussions of the mechanics of specific management tools. Dur- theses of available scientific information are presented to sup- ing my sixteen years of interactions with sequoia managers port this analysis. The final section offers some general and the interested public, I have come to conclude that mean- conclusions and summarizes some of the alternatives for ingful debate about sequoia management has been most hin- implementing giant sequoia management. dered by people’s differing assumptions as to the fundamental nature and dynamics of sequoia ecosystems. By focusing on general principles, then, this chapter helps lay a necessary foun- dation for informed discussion among scientists, policy-mak- ers, managers, and the public. The critical review of principles PRESENT GROVE CONDITIONS will also help managers set justifiable, site-specific goals and objectives, and implement sequoia management practices that Giant sequoias are the largest trees on the planet and are are based on sound science and consistent with policy. Addi- among the oldest, sometimes living for 3,200 years or more. tionally, by focusing on principles the chapter becomes relevant They often occur in stately groups which some people have to sequoia grove management in general, not just the manage- likened to living cathedrals (figure 55.1). Few organisms on ment of groves in the Sequoia National Forest (as emphasized the planet, plant or animal, have inspired as much human in the SNEP charge). admiration. The third underlying premise, consistent with the policies Sequoia groves are portions of Sierra

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