"The most important characteristic of an organism is that capacity for self-renewal known as health. There are two organisms whose processes of self-renewal have been subjected to human interference and control. One of these is man himself. The other is land."

Aldo Leopold (1949)

This report documents an ecological assessment of forest ecosystem health in the Southwest (Arizona and New Mexico). The assessment focuses at the regional level and mostly pertains to lands administered by the National Forest System in the Southwestern Region. Information is presented for use by forest and district resource managers as well as collaborative partners in the stewardship of these lands and resources. The report establishes a scientific basis for conducting forest health projects, provides a context for planning ecosystem restoration, and contributes to the understanding of the physical, biological, and human dimensions of these forests. Chapters describe Southwestern forest ecosystems of the past, changes since the Colonial Period, and consequences to biodiversity, resilience, biotic integrity, and human use. Opportunities, tools, and research needs for improving ecosystem sustainability are also identified.

The definition of forest health is controversial. The concept of health is well understood as applied to humans but may not be appropriate for ecosystems. Defining health in terms of homeostasis, whereby any change in condition represents a decline in health, fits humans well but not ecosystems. A human is an organism with a highly integrated physiology; survival requires precise regulation of internal temperature. An ecosystem, however, is a dynamic community of competing and evolving populations bound by common energy pathways and nutrient cycles. Although ecosystems display stability, they are not homeostatic organisms. Similarly, human health can be defined by the absence of disease from parasites, bacteria, and viral infections. But in ecosystems, herbivorous insects, parasitic plants, and decay fungi are essential members of the biotic community with important roles determining ecosystem structure and function. It is only when their numbers increase beyond a range of historic variability, persist at chronic high levels, or when exotic species are introduced into the ecosystem that these disturbance agents might be considered indicators of unhealthy forests. The difficulties of defining an optimal condition for ecosystem health, coupled with the lack of universally accepted indicators to measure ecosystem health, have led some scientists to conclude that the concept of ecosystem health is ecologically inappropriate (Wicklum and Davies 1995).

Although the analogy of forest health with human health is invalid, there are general concepts applicable to all complex dynamic systems that can be used to describe and assess their condition. Sustainability–a comprehensive, multiscale measure of system organization, resilience, function, and productivity–is proposed as a more useful concept than stability or absence of disturbance (Costanza et al. 1992). This property accounts for the dynamic nature of ecosystems and their adaptability to disturbance. Expressed in terms of biodiversity, resilience, biotic integrity, and human use, sustainability can be described at different scales of an ecological hierarchy and for biotic communities of any species composition. Although there are no simple and inexpensive methods for assessing ecosystem health, progress has been achieved over the last decade in development of data collection methods, identification of appropriate indicators and indices, and construction of diagnostic models. Defining and assessing the health of complex ecosystems is not easy, but it is not impossible.

For practical reasons, it may be unimportant to define forest health in other than "fuzzy" terms (More 1996). One of the strengths of the forest health metaphor is that people can relate to it (Rapport 1995). A consensus on the need for forest health is sufficient to bring together resource managers, lawmakers, and the public. Most people have an intuitive idea of what constitutes a healthy ecosystem; at least, they believe they can recognize an unhealthy one when they see it. Perhaps more than any other event, the Yellowstone Fire of 1988 drew attention to the health of America's forests. Images of other devastating wildfires were kindled by media exposure of the destructive Dude Fire in 1990 and the fatal Storm King Fire in 1994. After decades of successful fire suppression, did these catastrophic fires indicate something was seriously wrong? In 1994, the Forest Service contracted with Kaset International for an independent poll of U.S. residents to learn what the public valued from its forests and what were their concerns over resource management. Even though no definition of forest health was provided, respondents overwhelmingly identified healthy forests as important and their protection as a high priority.

Although a general concept of forest health may be enough to bring people together over specific issues, resource managers also need the ability to assess overall ecosystem health. Attempts to translate general concepts of ecosystem health into operational standards have resulted in definitions that either focus on ecosystem structures and functions or on the capability to provide for human needs. Kolb et al. (1994) reviews a number of definitions and categorizes these perspectives as ecosystem or utilitarian. Kolb et al. (1994) proposes that healthy forests are distinguished by four qualitative attributes:

1. the physical environment, biotic resources, and trophic networks to support productive forests during at least some seral stages,

2. resistance to catastrophic change and/or the ability to recover from catastrophic change at the landscape level,

3. a functional equilibrium between supply and demand of essential resources (water, nutrients, light, growing space) for major portions of the vegetation, and

4. a diversity of seral stages and stand structures that provide habitat for many native species and all essential ecosystem processes.

Within the Forest Service, the definition of ecosystem health and its integration into goals and activities has evolved since 1988 from three different sources–forest pest management, global change (fire and atmosphere), and ecosystem management. As a consequence of various national strategic plans and programs, the Forest Service mission, and regional assessments (Wickman 1992, Quigley 1992, O'Laughlin et al. 1993, Everett et al. 1994, Campbell and Liegel 1996, Clark and Sampson 1995), a consensus is emerging on how to combine the utilitarian and ecosystem perspectives and what standards to use for judging biodiversity, biotic integrity, resilience, and human use.

An early definition of ecosystem health developed from the forest pest management perspective. Forest health is a condition where biotic and abiotic influences on the forest (i.e., insects, diseases, atmospheric deposition, silvicultural treatments, harvesting practices) do not threaten management objectives for a given forest now or in the future (McIntire 1988). The initial plan of providing forest health through silviculture and integrated pest management (McIntire 1988) was revised and given specific goals in a new strategic plan (USDA Forest Service 1993a). Although the initial definition of forest health was retained, greater weight was given in the revised plan to ecosystem management and maintaining functioning communities of plants and animals, including species formerly considered as "pests". Nonetheless, the goals of planning, prevention, suppression, protection, monitoring, restoration, and exclusion still mostly reflected an entomology and pathology perspective. In a 1994 update (USDA Forest Service 1994c), three key indicators of forest health are identified as change in forest area, tree growth, and mortality. Forest health concerns focused on threatened tree species and damaging agents.

Based on two workshops in 1987 and 1988, the USDA Forest Service (1988) proposed a research program for assessing forest health and productivity in a changing atmospheric environment. This program focused on issues at a global scale, incorporated atmospheric and other ecosystem processes into consideration of forest health, and identified the need for large scale monitoring and ecosystem models. Concerns over atmospheric pollution and climate change, as well as various forest declines and pest outbreaks, spurred participation by the Forest Service in a broad cooperative program (USDA Forest Service 1994a) called Forest Health Monitoring (FHM). The FHM program was designed to estimate the status, changes, and trends in selected indicators of forest ecosystem conditions on a regional basis (statewide and larger). In particular, this program was given responsibility for monitoring and reporting on ecosystem health, including air pollution effects on forests and insect, disease, and other stressor effects on forest ecosystems at the regional scale. Surveys conducted under this program emphasized change in forest area, tree growth, mortality, and crown appearance and tree damage caused by insects, pathogens, and abiotic agents (e.g., see Campbell and Liegel 1996).

Since 1994 the official mission and vision of the Forest Service is described in terms of ecosystem management (USDA Forest Service 1994b, Thomas and Huke 1996). In this context, ecosystem management refers to the integration of ecological, economic, and social factors to maintain and enhance the quality of the environment to best meet current and future needs. The focus priorities for the agency are protection, restoration, sustainability, and organizational effectiveness (USDA Forest Service 1994b, Thomas and Huke 1996). An integration of biophysical and human dimensions is described for each of these priorities. Protection through an understanding of the roles of various disturbance agents ensures the health and diversity of ecosystems while meeting people's needs. Ecological restoration using prescribed fire, thinning, and other management tools improves the likelihood that future options for resource use are maintained. In addition to providing multiple benefits for people within the capabilities of ecosystems on National Forest System lands, the agency supports action that incorporates sustained economic, sociocultural, and community goals consistent with a shared vision of desired ecosystem condition (Interagency Ecosystem Management Task Force 1995). The fourth focus priority, organizational effectiveness is achieved by using appropriate scientific information and involving diverse communities in making resource decisions. With these four priorities included in the meaning of ecosystem management, forest health (as a component of ecosystem management) gains an economic and social context. This context of the human dimension complements the ecological perspective provided by programs focused on vegetation condition and tree damage.

Although the Forest Service has not yet adapted an official definition of forest health, there is an interim definition which reflects the evolving ideas described above. Twery and Gottschalk (1996) propose:

forest health is a condition wherein a forest has the capacity across the landscape for renewal, for recovery from a wide range of disturbances, and for retention of its ecological resiliency, while meeting current and future needs of people for desired levels of values, uses, products, and services.

This is the definition of forest ecosystem health accepted by the Southwest assessment team and used in this report. The philosophy of ecosystem management–looking at ecosystems as interacting systems rather than individual components, incorporating multiple spatial and temporal scales, and recognizing that ecosystem management incorporates the human dimension as well as the biophysical dimension–has profoundly affected the way the Forest Service addresses forest ecosystem health.

ECOSYSTEM MANAGEMENT

Ecosystem management is the overall concept which determines the Forest Service approach to restoring and maintaining forest health (Thomas and Huke 1996). The principles of ecosystem management emerge from both a philosophical land ethic and from various legislative acts. Although other organizations have embraced ecosystem management with their own meaning and context, the Forest Service uses the following definition (Thomas and Huke 1996):

ecosystem management is a concept of natural resources management wherein national forest activities are considered within the context of economic, ecological, and social interactions within a defined area or region over both short and long term.

The land ethic behind ecosystem management traces back to Leopold (1949) and his call for a stewardship that goes beyond treating the land as a commodity. Ecosystem management is a shift in focus from managing outputs of ecosystems to maintaining the structure and function of ecosystems through time and for the benefit of present and future generations. The application of ecosystem management in the Forest Service involves four principles–public involvement, an ecological approach, partnerships, and management based on sound science (Thomas and Huke 1996).

The public is a partner in ecosystem management because people are an inseparable part of ecosystems and ecosystem management itself is a human endeavor (Carr 1995). Leopold's (1949) land ethic is based on the observation that people's beliefs and perceptions about the land influence how they treat it and what they expect from it. An understanding of the human dimension is as significant as the physical and biological dimensions for explaining how current ecosystem conditions (e.g., health) came to be. Forest health issues stem from human activity, are brought to light because of human concerns, and are addressed through human ingenuity (Carr 1995). Aspects of the human dimension include past and present land use, myths and beliefs, socio-economic structure and processes, demographics, lifestyles, and expectations.

The ecological approach to management is based on the observation that ecosystems are organized and behave according to certain physical and biological principles. The biotic members of an ecosystem are connected and interdependent; this includes humans. Ecosystems are dynamic; attempts to maintain them in a static condition can result in violent reaction (e.g., attempts to remove all fires from some ecosystems result in more serious fires). The boundaries of these interdependent and dynamic ecosystems are defined by geology, climate, and biotic history, not by administrative convention. Ecosystems are organized in hierarchical patterns so that actions at one level can have consequences at another (e.g., global warming can induce local extinction of a species). To be successful, management must be adaptive, taking into account the productive capabilities of the ecosystem, its ability to change, and its response to manipulation.

Because ecosystems are nested into larger and larger, interconnected units that cross many administrative boundaries, collaborative partnerships are necessary to make good decisions based on sound science. Stewardship requires the cooperation of multiple, public stakeholders and among managers and scientists of many agencies and disciplines. The elements of collaboration are–jointly develop shared vision and common goals; share responsibilities to obtain common goals where appropriate; and jointly work to achieve common goals using each collaborator's experience (USDA Forest Service 1994d).

Ecosystem management is based on sound science. This requires an understanding of how ecosystems function, how they support and tolerate human use, and how policy and management affects the environment (Thomas and Huke 1996).

Ecosystem management is based on the legislative authority and responsibility of the Forest Service as provided in numerous public laws. Statutes include the Multiple Use-Sustained Yield Act (1960), the National Forest Management Act (1976), National Environmental Policy Act ( NEPA, 1969), Endangered Species Act (ESA, 1973), and pollution control laws such as the Clean Water Act and Clean Air Act. Funding to implement ecosystem management is provided by annual appropriations, partial returns from timber sales as provided in the Knutson–Vandenberg Act (K-V, 1930), and numerous partnership programs.

Ecosystem management is also embraced outside the Forest Service. In 1993, the Society of American Foresters appointed a task force to produce a report on sustaining long-term forest health and productivity. The report contained 26 recommendations within four broad areas–;advocating ecosystem management, integrating ecosystem management into educational programs, promoting ecosystem management research, and coordination among landowners and with the public. Although the report represented an evolution of thinking among some prominent Society members, it failed to adequately address differences in a number of regional issues. In 1996, a broader task force reported to the Society on these regional issues and the connection of forest health to landowner objectives.

ADAPTIVE MANAGEMENT

The proactive approach of the Forest Service to restore and maintain healthy forests is adaptive management. The theory and practice of adaptive management has evolved over the last two decades through the works of Walters (1986), Holling (1978), and Lee (1993). One of the fundamental tenets of adaptive management is that ecosystems and people are unpredictable as they evolve together. Ecosystems change as do the people that attempt to understand and manage them. In addition, the understanding of ecosystem behavior is imperfect, and managers will never be able to completely predict responses to management activities. Adaptive management encompasses both deliberate experimentation to gain new knowledge (active adaptive management) as well as the ongoing process of using monitoring and inventory information to assess the effects of management actions on ecosystem health (passive adaptive management). Active adaptive management is a departure from traditional management in that it views management actions as experiments from which to learn. Implementing adaptive management experiments involves being explicit about expected outcomes, designing methods to measure responses, collecting and analyzing information to compare expectations to actual outcomes, learning from the comparisons, and changing actions and plans accordingly (USDA Forest Service 1995). Collaboration with research is essential to provide the expertise on designing adaptive management programs so that they can be monitored and evaluated. Passive adaptive management may seem a misnomer because it requires a very active program for monitoring and evaluation of project activities, as well as some aspects of management experiments. Particularly for effectiveness and validation monitoring, the monitoring must be designed as statistically sound and scientifically credible.

With adaptive management, specific treatment actions are determined using an ecological approach to implement land management plans on each national forest. Project-level analyses are done in the context of broader scale assessments that identified desired conditions for healthy, sustainable ecosystems. Desired conditions for sustainable forest management are identified using public participation and collaboration in consideration of local management objectives and local conditions. Desired conditions provide descriptions of the desired human dimensions and physical, biological characteristics to be achieved in an area over short and long time frames.

RISE OF THE FOREST ECOSYSTEM HEALTH ISSUE IN THE SOUTHWEST

In many respects, the Forest Service, Southwestern Region was a pioneer in adopting a broad perspective of forest ecosystem health. The emphasis on ecosystem health at the regional level began in 1992 with the adoption of a series of initiatives to address forest health in specific, threatened, biotic communities, namely pinyon–juniper, riparian, and aspen. In 1993, initiatives for these communities were combined with those for the remaining forest communities as the Forest Health Restoration Initiative (USDA Forest Service 1993b). The goal of this program was to increase public awareness in forest ecosystem health, gain agency and public support, and begin the work of ecosystem restoration.

In 1994, the Southwestern Region developed a report on the human dimension of ecosystem management (USDA Forest Service 1994d). The report states that ecosystem management must include consideration of the physical, emotional, mental, spiritual, social, cultural, and economic well-being of people and communities within ecosystem capabilities. The report further observes that managerial decisions are in reality moral rather than technical judgements because they accommodate some people's values and not others. This underscores Carr's (1995) characterization of the complexity of these decisions and recognizes that there is rarely one correct solution for natural resource issues, only more or less useful solutions. The Southwestern Region and Rocky Mountain Forest and Range Experiment Station have several excellent collaborative projects. The Keystone Center (1996) highlights the Malpais Borderlands Group as a laboratory for demonstrating public involvement and collaborative techniques in the spirit of ecosystem management. The Yavapai Ecosystem Project received the Chief's Ecosystem Management Award for their innovative private-public cooperative strategy to sustain ecological integrity while still allowing economically viable ranching operations.

The Southwestern Region Leadership Team in partnership with the Rocky Mountain Station requested a detailed assessment of forest ecosystem health as an extension of the Forest Health Restoration Initiative. The Western Forest Health Initiative, announced in 1994, recommended development of regional assessments to describe the existing health of all Western Forests. This document details ecosystem health in forests of the Southwest.