Policy Conflicts Relative to Managing Fire-Adapted Forests on Federal Lands The Case of the Northern Spotted Owl Larry L. Irwin and Jack Ward Thomas
Introduction
Ecosystem management is concerned with the general goal of restoring and sustaining ecological integrity (Grumbine 1993). Management actions along those lines are frequently forced by a determination by the U.S. Fish and Wildlife Service that a species is threatened or endangered. Such a determination requires the preparation and adoption of a recovery plan and an identification of critical habitat. It is well to remember that the stated purposes of the Endangered Species Act (ESA) include…” to provide a means whereby the ecosystems upon which endangered and threatened species depend may be conserved…”. The ESA therefore is the “trip wire” that dictates ecosystem management, especially for federal lands. Among other things, reaching ecosystem management goals for public forested lands involves activities that maintain viable populations of wildlife that are associated with latesuccessional or old-growth forests, due to the relatively rapid reduction of such forest lands compared to the long periods of time required to re-grow those conditions. In the Pacific Northwest and other locations forest ecosystem management has thus evolved to include maintenance of a network of late-successional reserves (LSRs) on federal lands as the primary means for maintaining viable populations of the full suite of wildlife species associated with that forest condition. The LSRs originated to protect the northern spotted owl (Strix occidentalis caurina), which is listed as threatened under the ESA. Here, we address conflicts in federal policies between short-term conservation of northern spotted owls and long term restoration of sustainable forests, including late-successional conditions, emphasizing federal lands along the eastern slope of the Cascades in the Pacific Northwest. Although the predominant habitat of the northern subspecies of the spotted owl is widely believed to occur in relatively “wet” Douglas-fir/western hemlock forests west of the Cascades crest, the spotted owl occurs more widely in forest ecosystems with fire regimes characterized as moderateto high frequency and low intensity (hereinafter described as “fire-adapted”). In fact, there is evidence (Burnham et al. 1996) that the northern spotted owl is more productive in the eastern Washington Cascades mixed coniferous forests than in the moist forests of western Oregon and Washington. The northern subspecies also occurs in fire-adapted forests along the eastern slope of the Cascades in Oregon, in southwestern Oregon and in northern California (Franklin et al. 2000). The other two spotted owl subspecies occur perhaps even more generally in fire-adapted forests, including the California spotted owl (S. o. occidentalis) in the Sierra Nevada Range (Verner et al. 1992) and the Mexican spotted owl (S. o. lucida) in mixed coniferous forests in Arizona and New Mexico (Gutiérrez et al. 1995). Throughout the range of the northern spotted owl, natural wildfire patterns have a long history and were sometimes catastrophic ones (i.e., stand-replacement fires burning over landscapes larger than townships) that eliminated owl habitat for decades to centuries (Agee and Edmonds 1992). In other forests, disturbances were frequent and of low intensity and magnitude, keeping forest stands relatively open. In fire-adapted forests that encompass the range of the spotted owl, research has shown that late-successional forest (LSF) has increased during the past 100 years of forest succession, following early-day partial cutting and subsequent protection against wildfires (Covington et al. 1994, Everett et al. 1994, Lehmkuhl et al. 1995). To our knowledge, no estimates have been made regarding the extent to which such gains through forest succession have been outpaced by losses to clearcut timber harvesting in more mesic late-successional forests the past 50 years. In the East Cascades sub-region, fire suppression and removal of commercially valuable shade-intolerant species, such as ponderosa pine (Pinus ponderosa), favored shade tolerant
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Douglas-fir (Pseudotsuga heterophylla) and true firs (e.g., grand fir, Abies grandis) in very high stand densities (Camp et al. 1997). In turn, these dense conditions have had a major effect on insects and diseases, whose incidence increased dramatically in the past 50-100 years (see Section 6). These conditions, combined with yesteryear’s high-grading and subsequent forest succession, dramatically increased the threat of catastrophic wildfire (Agee 1994, Camp et al. 1997, Everett et al. 2000). Ironically, these events probably allowed northern spotted owls to occupy formerly open ponderosa pine forests that, historically contained little suitable habitat. The changes also shifted wildfire regimes from frequent low-intensity fires to less-frequent, high-intensity, stand-replacing fires (see Section 2). For example, the Tyee fire in 1994, a stand replacement fire of 140,000 acres in low and mid-elevation forests, and other fires destroyed at least 12 spotted owl nest locations, reduced habitat for over a dozen additional owl pairs, and reduced connectivity within the LSR network in the Eastern Washington Cascades (Bevis et al. 1997, Gaines et al. 1997, Everett et al. 2000). Additional township-sized wildfires occurred in 2000. In anticipation of such events, Thomas et al. (1990) and FEMAT (1993) designed the federal LSR network such that the loss of single LSRs could be tolerated without compromising recommended spacing. In fact, the strong likelihood of such relatively large-scale disturbances was predicted by both the Interagency Scientific Committee (ISC), who proposed the original reserve system for the northern spotted owl, and by FEMAT, who made allowances for active management to reduce the probability of such occurrences. However, such opportunities for preventative forestry were not used by federal managers. We discuss this point in more detail below under Adaptive Management. Verner et al. (1992) noted that wildfires in the Sierran mixed-conifer forests represent the greatest threat to habitat for California spotted owls. Similarly, Agee and Edmonds (1992) noted that active forest management is necessary to preserve habitat over the long run in all sub-regions occupied by the northern spotted owl, especially in the Klamath and East Cascades sub-regions. As the U.S.D.A. Forest Service (2000:9) noted, “dwindling habitat for many threatened and endangered species in fire-adapted ecosystems will eventually be affected by wildland fire”, and without intervention in susceptible forests, “fire could eventually push declining populations beyond recovery”. Further, global warming over the next several decades, whatever its causes, portends to exacerbate an already serious situation that exists in fire-adapted forest ecosystems from British Columbia to Mexico. The foregoing clearly suggests that a simplistic “no-touch” short-term, risk averse policy for protecting northern spotted owls conflicts with long term restoration of sustainable forest ecosystems in fire-prone landscapes. However, the concomitant reduction in late-successional forests and the associated fragmentation of available habitat for northern spotted owls presented a management paradox. Although maintaining adequate amounts of habitat is more of a problem than habitat fragmentation (Meyer et al. 1998), this circumstance led to a situation where, in the short term at least, it was considered essential to cease activities that would lead to continued habitat declines. On the other hand, many of the spotted owl habitats that developed as a result of fire exclusion and many others are at high risk of catastrophic fire unless treated. The challenge involves how to integrate the necessarily narrow focus of federal regulatory agencies with broader objectives of federal land managers. Federal land managers endeavoring to maintain and restore late-successional forest habitats are willing to face important short-term risks in restoring landscapes with altered fire-, insect and pathogen disturbance regimes where management success is uncertain and the law allows. For example, directives in the Northwest Forest Plan for National Forest lands within the range of the northern spotted owl recognized the need to manage actively within and outside LSRs to restore sustainable stand and landscape conditions and natural fire regimes to meet the conservation goals of the Plan (FEMAT 1993). As such, the Okanogan and Wenatchee National Forests developed and implemented a Dry Forest Management Strategy (E. Thomas, pers. comm., Wenatchee/Okanogan National Forests), and the Gifford-Pinchot National Forest is making similar plans for its eastside forests (Méndez-Trenneman 2001). Yet federal regulatory agencies such as the U.S. Fish and Wildlife Service or National Marine Fisheries Service, which focus on short-term protection of threatened species under the Endangered Species Act or aquatic resources under the Clean Water Act, respectfully, are generally more risk averse than federal land management agencies. The responses from federal regulatory agencies relative to northern spotted owls has been that any short-term stand manipulations designed to reduce amounts and continuity of fuel loads and increase long-term resistance to fire and insect and
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disease disturbances are generally thought to increase sedimentation in streams and also decrease spotted owl habitat. The prevailing belief among wildlife biologists is that thick understory conditions (i.e., multiple forest layers, dead wood on the forest floor) provide optimal conditions for owls to hunt their prey. Therefore, fuel-reduction programs could run afoul of the Endangered Species Act or Clean Water Act regulations. In fact, the federal regulatory agency responsible for protecting northern spotted owls, the U.S. Fish and Wildlife Service, provided context for the above-described conclusion by recently concluding in an opinion brief that thinning reduces owl habitat and would result in a regulatory “take” of a threatened species if conducted in the immediate 250 acres surrounding owl nest sites (The Oregonian, 29 and 30 Sept. 2001). The agency also determined that thinning trees more than 40 years old and removing younger trees would be allowed only if federal biologists, after evaluation of local conditions, conclude the operations would improve conditions for the birds, both short and long term. We think it is more likely that thinning results in a short-term negative effect subsequently followed by a longer term positive effect. For example, Verner et al. (1992:25), commenting about partial-harvesting in California spotted owl habitats, noted that they wouldn’t be surprised to find that a brief period, perhaps 5 years, lapses during which owls would initially avoid treated stands and then resume normal foraging activities. In fact, Verner et al. (1992) suggested that such treatments may improve habitats over the long run. Yet federal regulatory agency decisions inevitably will face heavy criticism from environmental interest groups and, perhaps, successful legal actions in allowing stand treatments that might well protect the stands in question from total loss to fire over the longer term. State and private forest landowners, attempting to integrate multiple goals including, economics, wildlife conservation and forest health, likewise are constrained by state and federal regulations to mitigate the effects of various timber harvest plans on northern spotted owls. For example, in the eastern Washington Cascades, the Washington Department of Natural Resources and Plum Creek Timber Company each developed comprehensive Habitat Conservation Plans. Each organization developed goals for guiding forest management along ecologically sound pathways while attempting to meet the regulatory guidelines for short-term maintenance of sufficient habitat for northern spotted owls. In the East Cascades Region, U.S. Fish and Wildlife Service regulations require maintaining at least 40% suitable habitat within a circle of 1.8-mile radius of spotted owl nest sites. However, because local spotted owl nest sites are about 1.5 miles apart on average, the regulatory owl circles overlap considerably, severely constraining the ability of state and private landowners to meet both ecological and regulatory goals. ARE THE OWLS TRULY AT RISK TO CATASTROPHIC WILDFIRE? Buchanan (1991), Buchanan et al. (1993) and Buchanan et al. (1995) were the first to raise concerns about possible risk of loss of owl habitat to catastrophic wildfires in the eastern Washington Cascades. They described vegetation structural conditions in half-acre plots surrounding 83 spotted owl nests and at random comparison samples. They found that 92% of the owl nests were in Douglas-fir trees. In the mixed coniferous forests there, nest-stand ages ranged from 54 to 700 years, with 73% of the stands with nests being in intermediate stages of forest succession while the remaining 27% were in old-growth forests. Reproductive rates of owls in those forests are among the highest reported for the range of the subspecies (Forsman 1996). Almost 50% of the stands with spotted owl nests in Buchanan’s (1991) study had been partially harvested, mostly 4 or more decades previous to the study. The apparent high-grading promoted dense pole-sized thickets of grand fir in the Grand Fir Zone and similar-sized Douglas-fir thickets in the Pine-Fir Zone. The high-grading probably also facilitated the spread of dwarfmistletoe (Arceuthobium douglasii), which was present in 70 of the 83 owl nesting stands. Spotted owls often used nests that had been abandoned by northern goshawks (Accipiter gentilis), which frequently constructed nests on dwarfmistletoe “brooms”. Dwarfmistletoe also is used by the northern flying squirrel (Glaucomys sabrinus), a major prey item for the northern spotted owl. Nest stands for owls often included mixtures of ponderosa pine, Douglas-fir and western larch (Larix occidentalis) as canopy dominants, whereas grand fir occupied sub-canopy positions. The abundance of 4-10 inch diameter grand fir trees in the sub-canopy is consistent with compositional and structural changes in similar mixed coniferous forests after the onset of fire suppression (Antos and Habeck 1981, Agee and Edmonds 1992). Buchanan et al. (1995) concluded
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that management efforts to control wildfires probably increased the amount of suitable owl habitat, but also resulted in a greater risk of habitat loss to catastrophic wildfire—a paradox of the first order. Fire protection produced the requisite habitat, which is protected for the owl, but it is now threatened by fire. To illustrate the extent of wildfire threat, we overlaid geographic information system (GIS) maps of wildfire condition ratings (Schmidt et al., in press) with northern spotted owl locations in the eastern Washington Cascades. Fire-regime condition classes involve the relative departure from historic ranges of variation in wildfire disturbance regimes. We found that 44% of the spotted owl locations occurred in forests classified as fire-regime condition class 3, which includes areas where fire regimes have been significantly altered, and an additional 36% of the owl territories occurred in forests in condition class 2, where fire regimes have been moderately altered (Table 1). Similarly, over half of the forested area contained in LSRs in that area appears at risk, with 31% occurring in condition class 3 and 23% in forests with moderately altered regimes. The most serious risk occurs in ponderosa pine/Douglas-Fir forests where 89 of 93 spotted owl sites were classified as being in forests with moderate or significantly altered fire regimes. These are the very areas where spotted owl reproductive rates are highest (Irwin et al., in prep.) An extended insect epidemic exacerbates the wildfire risk in the area. A western spruce budworm (Choristoneura occidentalis) epidemic has spread across large portions of the eastern Cascades since 1994 and continues to spread northward (Mendez-Trenneman 2001). Spruce budworms defoliate both large and small-diameter trees, particularly grand fir. The resulting mortality contributes to additional fuels on the ground and potentially more intense surface fires (Agee and Edmonds 1992). BALANCING SHORT-TERM CONSERVATION WITH LONG-TERM SUSTAINABILITY Aldo Leopold (1933) noted that the central thesis of wildlife management is that the same factors that historically destroyed wildlife and their habitats (ax, cow, plow, gun, fire) can be used judiciously and creatively to restore them. Thus, many writers suggest that harvesting trees can emulate some spatial fire patterns (Hunter 1993), or approximate stand structures similar to those created by fires (Bergeron et al. 1999). Yet judicious logging alone cannot be expected to replicate all aspects of fires (Carlton 2000), due, among other things, to multiple successional trajectories that depend upon a variety of processes associated with soils, moisture, activities of herbivores such as deer and elk and post-disturbance weather patterns. Further, it would seem logical that wildfires are a natural and perhaps an important part of sustaining some forest ecosystems, with some dead trees as a component. If so, prescribed fires should be helpful, at least in areas with natural fuel loads. There is at least one documented case where light ground fires were ignited in sites with relatively sparse fuel accumulations to reduce the chances of spread of stand-replacement fires that very likely would have destroyed several spotted owl nest sites in Arizona (Farnsworth 2000). In the situations discussed herein, we are interested in forests at risk to unnatural, catastrophic wildfires where prescribed fires constitute an unacceptable risk of producing such catastrophic fires until fuel loads, both live and dead, are mechanically reduced. Thinning or partial cutting is necessary in forests with uncharacteristic fuel hazards before prescribed fire can be applied with acceptable risk. As such, the National Fire Plan (USDA/USDI 2000) calls for reducing fuels in wildlands at risk from uncharacteristic fire effects. Thus, the Wenatchee National Forest, under its Dry Forest Management Strategy, plans to employ thinning from below to approximately 60-80 square feet per acre basal area, in a patchy leave-tree structure similar to structural configurations that were determined by research (Everett et al. 2000) to have existed under natural fire and insect disturbance regimes. However, stands manipulated with such silvicultural prescriptions will be relatively open. Research in southwestern Oregon suggests that such open stands may receive little use by northern spotted owls, apparently because of dry conditions that reduce production of hypogeous fungi used by animals such as northern flying squirrels, a major prey species (Zabel et al. 1995). Use by owls may not recur until tree crowns begin to close (e.g., over 40% closure) and the forest understory shrub species increase. For example, ericaceous shrubs such as salal (Gaultheria shallon) and huckleberry (Vaccinium spp.) may be
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important to spotted owls via associations with the owl’s prey (Carey 1995). New decision-support tools are needed to help plan such manipulations to account for a variety of stand condition in areas occupied by northern spotted owls. In the Eastern Cascades sub-region in Washington, there is indirect evidence to support silvicultural programs that emphasize fuel reductions. For example, Buchanan and Irwin (1998) found that understory hardwoods such as Douglas maple (Acer glabrum), Columbia hawthorne (Crataegus columbiana) and Scouler willow (Salix scouleriana) were comparatively abundant around owl nest sites in fire-prone Ponderosa pine/Douglas-fir forests. These hardwood species all increase after thinning as well as burning (Irwin and Peek 1979). In addition, Sullivan and Sullivan (2001) concluded that group seed-tree and patch-cut systems maintained abundance, species richness and diversity of small mammals such as red-backed voles (Clethrionomys gapperi) and voles (Microtus spp.) in mixed Douglas-fir and lodgepole pine (Pinus contorta) forests, suggesting that important prey species can be maintained. Of course, there will be the question of “Who pays?” because silvicultural treatments such as thinning for fuel reduction often involve recovery of little commercial value: that is, thinning may return little short-term value for the cost. Should taxpayers, through the activities of federal land management agencies, bear the burden? Or, can a few commercially valuable trees be harvested to underwrite the effort without significantly diminishing habitat values for owls? Traditionally, there has been little funding for non-commercial timber fuel fire reduction programs (USDA Forest Service 1993). More recently, however, Congress appropriated $1.6 billion for the National Fire Plan in 2002 to increase firefighting resources and restore forested ecosystems at risk by thinning overly dense forests, although principal efforts are anticipated to emphasize the urban/forest interface, where the effects of catastrophic wildfire threaten homes. There may be extensive forests at risk to catastrophic wildfire where federal land management authorities deem it necessary to defray the costs of fuel treatments by removing some commercially valuable trees. There is evidence (Irwin et al. 2000) that northern spotted owls will hunt for prey extensively in managed stands without large-diameter trees or with only a few such commercially valuable trees left over from previous late-successional forests, provided that other important old-forest structures such as snags and fallen trees were available. Therein lies the rub with some environmental interests who do not wish any trees harvested for commercial purposes in National Forests. Certainly, the concerned public is generally aware of the fire-threat situation and may be willing to help bear the burden of fuel-reduction costs. For example, González-Cabán and Loomis (1997) canvassed California households regarding their willingness to pay for reducing fire intensity and acreage burned in California and Oregon’s spotted owl habitat in old-growth forests. On average, those in California households were willing to pay $80 annually for a 20% reduction in acreage burned in California and would pay $57 per household for the same reduction in fire in Oregon’s old-growth. For a combined California and Oregon program, California households would pay $92 annually. González-Cabán and Loomis’ (1997) analysis demonstrated that citizens perceive old-growth forests as important, particularly those that support unique species such as spotted owls. Therefore, there is public support, at least in California, for federal programs that reduce fire risk, and thereby increased sustainability over the long run, but do not necessarily produce significant revenues over the short run. ADAPTIVE MANAGEMENT CAN PROVIDE IMPORTANT ANSWERS Previous research on northern spotted owls focused on evaluating the impacts of clearcut timber harvesting and identifying the habitat values of older forest stages (e.g., Forsman et al. 1984, Carey 1985). Such efforts were a reasonable place to begin. However, the result was a regulatory perspective that removing even a single large tree was considered habitat loss, although no published studies have described the responses by spotted owls to removing fewer trees via thinning, selection, or modified shelterwood silvicultural systems. Recent research has demonstrated that physical features such as topography should figure into land management planning for northern spotted owls (Irwin 1994, Irwin 1998, Meyer et al. 1998). Fire ecologists know full well the effects of topography on wildfire behavior, so there would appear to be opportunities to develop firemanagement plans at the scale of an individual owl territory. But details for such site-specific
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planning and silvicultural intervention may require adaptive management programs in which the silvicultural manipulations are implemented in an experimental context (Irwin and Wigley 1993). The Interagency Scientific Committee (Thomas et al. 1990) and FEMAT (1993) promoted adaptive management as a means for identifying silvicultural practices on federal lands that might accommodate late-successional forest associated species such as northern spotted owls across a mix of managed and unmanaged forest landscapes. And 10 federal Adaptive Management Areas were established in President Clinton’s Northwest Forest Plan for learning how to use silvicultural practices to advance old-growth conditions more rapidly. Now, a decade after adopting the Northwest Forest plan, no federal research has been undertaken (or perhaps allowed) to evaluate how northern spotted owls respond in an adaptive management framework. Scientists demonstrated what happens with clearcutting in owl habitats, but know almost nothing about the effects of numerous combinations of other forest management practices associated with thinning, selection, or shelterwood systems of silviculture. Further, the Northwest Forest Plan assumed that the interim “default buffers” along stream courses would be altered and some management allowed once watershed assessments were completed. This would have afforded additional opportunities for “adaptive management tests”. However, these redundant buffers remain in place, nearly a decade later. The crucial aspects of the Northwest Forest Plan related to “adaptive management”, that is, the 10 adaptive management areas, thinning or partial harvesting in stands internal to latesuccessional reserves, and adjustments in widths and practices related to riparian buffers, have not been aggressively utilized to provide insights and new information. Yet solid scientific information is crucial to developing proactive management for maintaining habitat for northern spotted owls while taking into account the dynamic nature of such habitats. The “static habitat” approach has dominated and the risk to loss of those habitats due to catastrophic fire has progressively increased. To be sure, the U.SD.A. Forest Service and National Council for Air and Stream Improvement (NCASI) are currently jointly developing an adaptive management study that would evaluate spotted owl response to implementation of the Dry Site Strategy in the Okanogan & Wenatchee National Forest and vicinity. However, even there the amount of forest actually scheduled for treatment is too small to evaluate how spotted owls might respond to changes in habitat at the population level. Perhaps the stunted attempts to apply adaptive management concepts under the Pacific Northwest Forest Plan influenced McClain and Lee (1996), who wondered if it is truly possible that adaptive management, in concert with collaborative and social and natural science management, can account adequately for real and perceived risks and scientific uncertainty to natural resources in addition to environmental and social values over long- and as well as the short term. The biggest challenge may well lie in promoting the public will for innovative management programs that seek to balance short-term conservation needs with long term forest sustainability. Mullner et al. (2001) recognized that management paradigms have evolved away from autocratic natural-science based management which were the legacy of the “progressive era” in which administrative decisions were based on science as it was understood by professional employees. Recently, demands to increase both stakeholder involvement and multiple values across spatial scales while meeting legal requirements, have evolved to include landscapes and regions, and have led, at least theoretically, to collaborative natural- and social-science based management (Mullner et al. 2001). Norton and Steineman (2001) incorporated variation of natural systems into a multi-variable management model that may result in optimizing multiple social and economic values within a community-based ecosystem management effort. Their model offers a hope of people with differing value systems and underlying beliefs to choose mutually acceptable indicators and goals associated with the indicators. Their thesis elevates public perception and underscores the importance of education. In practice, however, most of these “collaborative” efforts have not held together for long (Mullner et al. 2001). Perhaps the U.S.D.A. Forest Service’s new “Charter Forest” concept for National Forests will prove more successful. Norton and Steineman’s (2001) ideas about optimizing social and economic values also elevate the importance of reliable decision-support tools. The lack of necessary and reliable analytical tools is often invoked by federal regulatory agencies to justify short-term custodial management (i.e., “preservation”) over long-term restoration. Toward that end, NCASI, several federal agencies, and several management-oriented conservation organizations are working to identify and implement new decision-support tools that better quantify the relative risks to natural
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resources of short-term habitat protection versus actively addressing long-term risks of uncharacteristic disturbances. In our opinion, deeper understanding and stronger technology for risk assessments will help enormously, such that society, decision-makers, and land managers may develop more-informed decisions regarding treatments that provide satisfactory protection for threatened or endangered species while also reducing risk of catastrophic fire and supporting local economies.
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Table 1. Fire-regime condition class ratings for northern spotted owl territory sites on the eastern slope of the Cascade Mountains, Washington, 2001. Risk of losing Class 1 Fire regime within or near historical range 2 moderately moderate Key components Low Departure of fire frequencies not >1 return interval altered by >1 Vegetation attributes intact and functioning moderately 100 (36.5) No. of owls (%) 54 (19.7)
10 altered 3 significantly altered high return interval departed by multiple return intervals altered significantly 120 (43.8) altered