Assessing forest ecosystem health in the Inland West.

Forest health is a condition of ecosystems that sustains their complexity while providing for human needs. Millions of western acres fail to qualify.

In many forested areas of the inland western United States, trees across large landscapes are dying faster than they are growing or being replaced. In other areas, conditions exist that virtually guarantee an onset of serious forest health problems, which may lead to large wildfires, reburning, erosion, and loss of habitat and property. In those areas, it is not just trees and their values that are at risk. Where terrestrial ecosystems are adversely impacted, the entire range of aquatic resources, wildlife, and other values are affected as well. The current conditions, many of which are unprecedented in recent times, demand urgent response. Forest managers on both public and private lands, even though they manage for a different combination of objectives, face a common forest health challenge when the forests in their care are deteriorating.

Within this region, there are also forest areas that, either through management efforts or natural controls, represent examples of healthy, thriving forest ecosystems. In both the healthy and unhealthy areas, managers are challenged to design forest health strategies that focus on: a) the prevention of socially undesirable forest conditions by protecting the forest from insects, diseases, and fire in an ecological framework and b) the restoration of socially desired forest conditions on those areas where it is needed. Management needs to reflect a strong commitment to retain healthy conditions for many values, as well as to study current variability in ecosystem conditions.

Forest health is defined in this context as a condition of forest ecosystems that sustains their complexity while providing for human needs, and it is clear that many of the forests in the Inland West fail the test. In areas where insects, disease, and wildfire are causing total or near-total tree mortality, the evidence of forest health problems is visual and stark. In other areas, visual evidence and widespread mortality may be lacking, but the onset of major ecosystem setbacks are assured by the existence of conditions that inevitably lead to large, stand-replacing wildfires. Managers are challenged to take rapid preventive action to restore these forests to conditions more similar to their historical range of variability, or, where that is judged not possible or desirable, to strive for another sustainable condition.

Without the application of needed silvicultural treatments within a fairly short time (15-30 years), there is great danger that over the next century this region's forest legacy will be a series of large, uniform landscapes recovering from wildfires and other widespread ecosystem setbacks. These landscapes will present future societies with a set of limited options and needlessly high costs that, in many ways, will mirror today's situation. Both now and in the future, the preferred situation is a more diverse, heterogeneous landscape that is more consistent with the historical range of variability, less susceptible to wide-area disturbances, and thus more easily sustainable.

FORESTS AT RISK

The forests at greatest risk are composed of an unsustainable combination of tree species, densities, and age structures that are susceptible to the fire and drought regimes common to the region. This is a particular problem in forests where the species mix has shifted dramatically away from ponderosa and other long-needled pines and toward firs. This species shift, attributable to a combination of logging, grazing, fire suppression, and related activities over the past century, has been well documented.

In a review of Idaho forest data for the period 1952 to 1987, Jay O'Laughlin of the University of Idaho found that western white pine and ponderosa pine components in Idaho forests had declined 60 percent and 40 percent respectively, while true firs, Douglas-fir, and lodgepole pine had increased 60, 39, and 15 percent. In Arizona's Coconino National Forest, Wallace Covington and Margaret Moore estimated that stem counts on basalt-derived soils had shifted from a pre-settlement average of 23 trees per acre to 851 today. On the Kaibab National Forest, presettlement tree densities on limestone soils averaged 56 per acre, compared to 276 today.

Under these altered conditions, competition for moisture and nutrients creates stress that exacts a significant toll in reduced growth, while opening the way for epidemic outbreaks of insects, disease, and wildfire. Wildfires in these ecosystems have gone from the high-frequency, low-intensity patterns that historically shaped and sustained the system to numerous high-intensity fires that require enormously costly suppression attempts, which often prove futile in the face of overpowering fire intensity. High fuel loads, related to the long-time absence of fire, and dead and dying trees, resulting from insects and diseases, have fed fire intensities, resulting in the destruction of soils, watersheds, fisheries, and other ecosystem components.

WILDFIRE THREATS HAVE CHANGED

Change agents and processes such as drought, pests, and wildfires are normal components of forest environments. Unfortunately, the current conditions in many Inland West forests allow these normal situations to become catastrophic events. Unless the land conditions themselves can be improved, these catastrophic changes seem certain to continue. On the Boise National Forest, for example, wildfire burned an average of 3,000 acres per year from 1955 to 1985. From 1985 to 1992, the average annual wildfire acreage jumped to 56,000. These include intense, stand-replacing wildfires in ponderosa pine forests, indicating a major shift away from the type of fire regime these forests experienced in the pre-settlement era.

The 1992 Foothills Fire provides an example of the type of events that seem certain to continue. This wildfire, which started on public rangelands east of Boise, Idaho, on August 19, 1992, burned more than 259,000 acres, including about 160,000 acres of national forest land. Trees, including isolated pines and small timbered pockets, were uniformly killed throughout the fire's area. The largest ponderosa pine in Idaho--a veteran of dozens of previous fires over its centuries of life--was killed, indicating that this wildfire was more intense than any the tree had previously experienced. Trees containing an estimated 300 million board-feet of merchantable timber were killed, along with young tree growth across the fire's area. One population of rare bull trout was wiped out, and another seriously threatened, as intense heat denuded the riparian-zone vegetation and heated small streams. Watershed functions were altered through vegetative change and the occurrence of water-repellent soils resulting from intense heat.

Federal costs for fire suppression and emergency restoration on the fire-damaged national forest land totaled approximately $24 million. The need for additional management and investment is far from over; the young ponderosa pine regeneration must be thinned and protected from future fires that could kill the seedlings before they mature sufficiently to produce new seed sources. An intense reburn in the next few years could cause a widespread change to grassland or shrub and brush fields over wide areas that have been forested for many decades or longer.

Situations similar to what existed on the land impacted by the Foothills Fire are common in many regions of the Inland West. Because these situations reflect conditions outside the historical range of variability characteristic of these sites, we believe natural forces are unlikely to correct them in ways that will satisfy the public's expectations for healthy forests. Change will continue, that is certain, but the result of that change is far from known. The changed forest may be what people consider to be healthy and productive, or it may not. The choice we face is whether to leave the outcome to chance, or to try to guide it toward desirable conditions through what Aldo Leopold described as "intelligent tinkering" with the forest ecosystem.

THE RISK OF INACTION 

Though it is readily recognized that scientific knowledge is incomplete, modern ecosystem theory provides a basis for corrective actions that can mitigate current levels of risk and potential damage, and facilitate improved forest health. Through corrective actions and ecosystem management, a balance of forest structures can be achieved across landscapes that will increase the opportunity for maintaining biological diversity and reduce the impact and scale of inevitable disturbances.

The question of risk is at the heart of the options facing society in the inland western forests. Any management action--including the option of taking no action at all--has certain costs and uncertain outcomes. It takes courage and leadership, in the face of uncertainty and public cynicism, to take actions that are inconsistent with past practices. This is, however, what is demanded in the current situation facing Inland West forests and forest managers.

The authors conclude that in many of the Inland West forests, the costs and risks of inaction are greater than the costs and risks of remedial action. Inaction in the face of current forest conditions will likely prove to be the most costly and environmentally destructive option. The judicious control of tree density and species composition through prescribed fire, thinning, and other silvicultural methods is critical to reducing risk and restoring and maintaining forest health. These conclusions may be inconsistent with what citizens, scientists, and policymakers have learned in other forest regions where ecosystem management is perceived to require less intensive human intervention in the forest.

The current ecological conditions in the forests of the Inland West, however, lead to the conclusion that successful ecosystem management will demand increased management that is more intense but different from what has historically been done. In most cases it will be a more adaptive form of management, more responsive to local conditions and needs, with results more closely monitored to study effects and continuing changes. The challenge to managers on these threatened forests is to provide preventative treatment as a means both of protecting valuable resources and reducing the effort and cost of such current management activities as fire suppression and emergency restoration.

DETERRENTS TO TIMELY RESPONSE

A concern remains about the capacity of federal land-managing agencies to respond rapidly and adaptively to take actions necessary in high-risk situations. Federal forest-management and environmental laws charge the land-managing agencies (primarily the Forest Service and Bureau of Land Management) with assuring continued ecosystem health and sustainability. Unfortunately, the procedural, regulatory, and judicial framework that has developed in response to that complex array of federal laws imposes time delays that, in many cases, prevent the agencies from taking timely action to address fast-changing situations in the forests. This is compounded by a lack of public trust that results in appeals and litigation on most proposed actions involving tree removal or logging. The public is also generally unaware of the extreme risks to the forest and adjacent private property inherent in the current situation, so they fail to see the potential price of "doing nothing."

Public understanding, acceptance, and support for management intervention in unhealthy forest situations is unlikely to result, however, from attempts simply to "educate" people. Instead, research needs to provide analytic and illustrative tools that will help concerned citizens and agencies understand forest conditions and related risks. People will need to see the forest with their own eyes, and be able to see how risk ratings and other decision tools have been calculated. They will need to understand not only the likelihood of undesirable forest changes, but what those changes will mean in terms of altered values such as visual quality, wildlife habitat and numbers, fisheries, water quantity and quality, and recreational opportunity. They will have to come to a personal acceptance of the fact that while all ecosystems undergo constant change, there are ecologically sound methods by which human intervention can guide change in ways that are ecologically, economically, and socially sound.

As scientists, land managers, and concerned conservationists, the authors believe it is imperative for national policymakers to recognize the unique and critical situation that currently threatens the forests of the Inland West. Immediate action is needed to encourage and support forest-management programs that maintain healthy forest areas, treat unsustainable conditions, restore forest health where needed, and prevent the widespread ecological setbacks and enormous public and private values that are currently at extreme risk.

ON VARIABILITY

Throughout the accompanying article, and increasingly in forest literature, the terms "historical range of variability," current range of variability," and "desired range of variability" appear. A word of explanation is in order.

Increasingly, ecologists have noted that forest systems seldom, if ever, reach a "steady state," whether they are managed by people or affected primarily by natural forces. What is constant is that forests are in a constant state of change. It appears, in fact, that many species have developed or adapted in response to these changes, and that slowing or halting the change process can threaten them.

As managers attempt to successfully manage a forest, they need some kind of model toward which to work. In many cases, the forest that grew on the site before management began is a good place to begin. But if the only model available is the one that someone found growing on the site when they arrived there, that may or may not be the best representation of what had happened over the prior forest generations.

The term "historical range of variability" is an attempt to explain the kinds, amounts, and speed of the changes that tended to occur on the forest before European settlement. Obviously, the history may be fairly obscure or, for that matter, fairly brief. In many forest areas (Alaska today is a good example), the current generation of forests may be the first since the last ice age. As these forests begin to be afflicted by widespread death and decline, there's very little basis upon which to predict what is likely to happen next. In contrast, many forests have a fairly long history, written in fire scars, old trees, tree remains, bogs, and fossils.

For each forest, then, ecologists today seek to understand what kinds of fluctuations seemed to be normal for the site. These historical variations can then be compared to today's conditions, as one guideline on the health and well-being of today's forests. For managers looking to the future, the concept of "range of variability" offers the chance to set a realistic, achievable range of targets toward which their current management can aim.

R. Neil Sampson is executive vice president for AMERICAN FORESTS, Washington, DC. David L. Adams is professor of forestry, College of Forestry, Wildlife, and Range Sciences, University of Idaho. Stanley Hamilton is director, Idaho Department of Lands. Stephen P. Mealey is supervisor, Boise National Forest, Boise, ID. Robert Steele is forest ecologist, Intermountain Forest and Range Experiment Station, U.S. Forest Service, Boise, ID. Dave Van De Graaff is regional timberlands manager, Boise Cascade, Emmett, ID. This article is excerpted from the summary of Assessing Forest Ecosystem Health in the Inland West, available this summer as Volume 2 of the Journal of Sustainable Forestry, 1994 in press, Haworth Press, Binghamton, NY.