The Health of Forests

Alan Wittbecker

Forest health has become an immediate concern. Health is one of the new buzzwords for ecosystem management. Some timber companies support the Forest Service idea of logging burned forests back to health. Some activists urge the government to set aside more wilderness so that forest health can recover. At several recent meetings, I encountered several different concepts of health. Perhaps they are all correct; but perhaps there is something more to consider.

I attended the Inland Empire Society of American Foresters (SAF) meeting a while ago. The meeting was called Foresters on the Issues. Health was one of the three main issues (along with Certification and Property Rights). The first speaker on Forest Health was John Beuter, Chair on the SAF National Commission on Forest Health. After identifying himself as a forest economist, he admitted he was "troubled by the idea of health." Beuter then made the following statements:

"forest health means different things to different people,"
"forest health is part of management,"
The next speaker was Winston Wiggins, who described himself as a "bureaucrat" with the Idaho Department of Lands. Wiggins said there was a "battle of values," while repeating many of the gems first polished by Beuter. He stated that the guiding principle of state land management was to create "maximum financial return to the state schools." He did take a stab at defining forest health as the ability "to continue to produce products in perpetuity." That is, productivity.

The final speaker, John Marshall, compared the first SAF Forest Health report (by Logan Norris at Oregon State University) with the new report by John Beuter. Then he criticized forest health as a concept as being "unscientific." Marshall said the concept of forest health was "subjective."

After the three talks, the moderator wondered: "If this is not forestry leadership, then what is?" (my first thought was the Girl Scouts they are less arrogant, more willing to spend time in the forest and learn, and willing to sell cookies to raise money, rather than collect government salaries, but I held my tongue). He then asked for questions from the listeners. Since no one else was at the microphone, I asked the first question: "To all three panelists, why can you not define forest health scientifically?"

Marshall answered first: "Because it is not a scientific concept."

Me: "Yes, it is. It may not be completely defined, but it is a legitimate scientific concept."

Marshall: "No, it is not scientific; it is emotional and social. It means different things to different people, as John said."

Me: "Yes, it is scientific. Let us use an analogy. You agree that gravity is a scientific concept [Marshall nods]; it can be measured precisely, etc. But to someone who fell down the stairs, it has emotional meaning that does not make it any less scientific. Forest health is a similar concept."

Marshall: "Precision is the difference."

Me: "But precision is not required for the concept to be valid; another analogy, with less precision: Medicine and mental health, just 30 years ago, were disease-oriented, not health-oriented; then in the 1970s, both became more health-oriented, defining health in positive terms, not just as the absence of disease. Forest health is where mental health was 30 years ago."

Beuter: "Can you define a healthy forest?"

Me: "Yes, I can, maybe not completely at once, but as continuity, functioning, uh<\‹>"

Beuter: "I just bought 200 acres of clearcut land. Is that a healthy forest?"

Me: "No, it does not meet the tests of structural/functional completeness or continuity."

Beuter: "Are you saying I am stupid?"

Me: "No, that is not necessary. But the forest is not healthy<\‹>in fact it is not a forest anymore."

Beuter: "My clearcut is a healthy forest. We planted 155,000 trees, with help from a Mexican cooperative. Why is it not a forest?"

Me: "If I eat the pear I got from the break table, it is not a pear anymore; it has contributed its materials to me. Maybe another pear will appear on the table, but the first one is gone. Cutting, clearcutting, the forest kills it. It does not exist anymore. The land may have the potential for a new forest, if the soil fungi is not dead and the squirrels, owls, bats, driven away. You just said you planted thousands of trees. Would you have had to do that if there was a healthy forest there?"

Beuter: "We planted to advance the succession; there are healthy trees surrounding the cut, the soil is okay."

Marshall: "I wanted to know how you can tell if people are healthy. By their looks right?"

Me: "By their looks as a first impression. Then by whether they are here next year; I would know more with a medical exam."

Marshall: "Can you define human health?"

Me: "Not being a doctor, not very well, but I could give you references to look up [audience laughs]. Well, I suppose I could, in general, um, vitality, uh ..."

Marshall: "My mother is healthy, but not as healthy as me, and I am not as healthy as Dan OBrien. Are we all healthy?"

Me: "Health is a continuum, like gravity. We could define human health, like we can with forest health, as functioning with a minimum of disease organisms always present."

Beuter: "Would you say Steven Hawking is healthy? [ed. shakes head and says no]. Let me make an analogy. Let us say I am God and Hawking is the land [audience laughs]. Then Hawking is doing what I want him to do<\‹>producing, ideas, despite his situation."

Wiggins: "We could say productivity is health."

Me: "Hawking has admitted being rather unhealthy. Ill health is not death, however. He can do what he does only with immense support from others. Another analogy: Badly stressed trees produce heavy seed crops in case they do not make it. Productivity and health have a complex relationship."

Beuter: "Productivity is doable. That is all we can define."

Me: "If I died, became a ghost, and was able to haunt you productively, would I still be healthy by your definition?" [audience laughs]

Moderator: "We have other people who want to ask questions. We should move on now."

This whole exchange was tape-recorded by several people<\‹>yes, Beuter did say "my clearcut is a healthy forest." What he was talking about was forestry as deforestation, which was, in fact, its original definition: the removal of all trees. When does clearcutting increase the health of a forest, if at all?

Definition: Health as Productivity and Growth
One thing I forgot to say was that forest productivity has an exact scientific definition (in terms of Gross Primary Productivity, Net Primary Productivity, and Net Ecosystem Productivity--although these are rarely all measured) and therefore, by their own arguments, forest health could be defined scientifically. But forest health is not related only to productivity. The forests they were talking about were plantations, with high GPP and NEP, that is, young growing trees. Old growth, with good GPP and NPP, and an NEP of almost zero, would not be considered healthy by these SAF scions yet, it would be very healthy by ecoforestry definitions.

In the organic world, growth is healthy only when the rate of change is decelerative in the long run; cancer and population are constant or accelerative. Industrial forestry tries to maintain then cut plantations after the rapid juvenile growth.

To relate health to growth and productivity, we could say that the capital of an ecosystem would be its physical environment and its gross primary productivity; interest would be the net ecosystem productivity. The production percentage would be the amount necessary to keep the ecosystem healthy.

Problems with Definitions
Our measurements of productivity, however, are not adequate. We are measuring over a year or two only to establish a growth rate or productivity. We should be measuring over centuries. A forest is a long-term, dynamically-changing being. We cannot use a short-term industrial approach to measure a few parameters and then pretend we know enough about a forest to cut a large percentage of it. Forests are created by slow processes that take hundreds or thousands of years. In their 36-year study of a 450-year old conifer forest in Washington, Jerry Franklin projected that it would take the shade-intolerant Douglas fir 750 years to drop out of the forest. Chris Maser points out how long it takes for coarse woody debris to decay (200-460 years). Soil formation takes millennia; rates can range from 50-100 years per centimeter.

The problem with health is that it is such a general concept, as OLaughlin says, a judgment "without an operational definition." Since ecosystems exist at all scales, it is hard to determine their health. Stress and pathology are normal parts of living systems; an outbreak in a small ecosystem may be part of a larger healthier system. Furthermore, not enough data exists about what levels of stress or pathology threaten the health of ecosystems--there is not enough data on ecosystems, not enough reference points or control groups.

Often foresters assess stand health rather than forest landscape health. Both are important, since stand health is a way of evaluating forest health over time. We do need baseline data, but it has to be from a comprehensive set of indicators, some of which may be qualitative and other quantitative. The data has to be collected religiously.

Assuming that forests are limited by the real biological constraints of ecosystems and biogeochemical cycles, a deductive, synthetic, conceptual model of forest health could be created, based on data generated from research on net primary (NPP) and net community (NCP) productivity. A deductive approach is necessary because accurate measurements of trophic level productivities (especially underground) in most ecosystems are lacking. A synthetic approach is necessary to integrate quantitative and qualitative data. The model must be conceptual because of the inherent fuzziness of the systems.

Redefinition: Health as Absence of Disease
A useful metaphor for forest health is human health, which has been studied for thousands of years. Our first clue to unhealthy people is abnormal behavior<\‹>not moving or breathing, for instance. The first thing we do is classify the symptoms. Then we measure vital signs: heart, blood pressure, temperature, and maybe white blood cell count. After a diagnosis is made, it is verified usually by more measurements. Doctors, who often rely on their long experience and learning, then discuss a prognosis and prescribe a treatment. So, health is considered the continuity of normal behavior.

Health was also defined generally as the absence of disease. By this traditional way, via negativa, health is not having cancer, infections, high blood pressure, diabetes, or other ailments. The opposite of health is disease. But, what is a disease? Many diseases, at some stage or concentration, obviously compromise health. But some human diseases, such as sickle cell anemia, make one healthier in the sense of being able to resist another worse disease, G-6-PD deficiency (glucose-6-phosphate dehydrogenase), a genetic disease that causes red blood cells to dissolve.

A definition of health is the condition of being sound in body or being well. The World Health Organization (WHO) defines health as a total physical, psychological, spiritual well-being of an individual. In forests this may be related to diversity. Diversity means species richness, different age and size classes in a population, and genetic differences in a species, as well as kinds of habitats present in an ecosystem and the kinds of communities occupying the habitats; and the kinds of ecological processes that maintain habitats; and the variety and richness of the planets genetic heritage in general. Forest ecosystems that have diversity are usually healthy.

Aldo Leopold started to describe a science of land health; "Health is the capacity of the land for self-renewal. ... A science of land health needs, first of all, a base datum of normality, a picture of how healthy land maintains itself as an organism." Notice that Leopold anchored this concept in a theory of organism rather than an ecological theory of community. Interestingly, the Buddha also gave an organismic definition of forest: "a peculiar organism of unlimited kindness and benevolence that makes no demands for its sustenance and extends generously the products of its life activity; it affords protection to all beings, offering shade even to the axeman who destroys it."

Problems with Redefinitions
Forests are not organisms in the strict sense, so the analogy is not perfect. The problem with the health of forests is that we do not have the same huge compendium of diseases and symptoms. In fact, we are just starting to compile the stresses and causes of forest illness. Furthermore, we tend to use our human values to judge health in forests; for example, we tend to think that forests should exhibit regularity, but many forests, such as boreal forests, are arrhythmic, that is they are punctuated by surprise events (as Holling suggests).

Human medicine itself is changing from being disease-driven to wellness oriented, from focusing on symptoms to describing the properties of health, such as interconnectedness and self-realization. Some ecologists or foresters, Rapport or Kimmins for example, define health as the potential for recovery after perturbations (such as logging); this definition still reflects human values. Forest health has to be defined without undue emphasis on human needs.

Forests are not just simple organisms; there are other differences. Forests live longer than humans. The difference in life-times makes discussions of health more problematic. Health can only be evaluated over time. The conditions of forests change over decades or millennia. When do we know if the change is succession or symptoms? Have we ever studied a forest for even one forest lifetime?

However, concepts of health applied to organisms can also be extended to communities and ecosystems. Both are complex whole systems with parts and functions. Of course forests are more complex than humans, which is also why we have trouble measuring social or cultural health (there is no standard society or standard forest as there is a "standard human"). That means we should be measuring a large number of variables, starting with soil depth (richness, compaction), then annual nitrogen uptake (often related to leaf litter), trophic flows, species counts, and patterns of activity. In forests, foresters usually measure the number and ages of trees, as well as canopy. Some foresters relate health directly to crown density and foliage loss as a percentage. But, assessing the loss has an element of subjectivity and there is disagreement about how much foliage loss is acceptable. Possibly, the presence of too many pests or diseases is the best indicator of the health of the system.

Redefinition: Health asVigor and Resilience
To be considered healthy, an ecosystem has to maintain its structure and metabolism (rate of energy use) despite occasional stresses. Robert Costanza proposes an operating index of system health that relates these components: HI = V*O*R, where HI is health, V is vigor, O is organization, and R is resilience (a form of stability).

Health is a dynamic measure of ecosystem organization, vigor, and resilience. Organization is described by diversity and connectivity; vigor is related to the amount and speed of productivity; and resilience is a measure of reaction to stress. Too much stress, for example, leads to unsustainable patterns of behavior; continuous stress leads to a breakdown of processes that becomes irreversible<\‹>the system dies. Quantifying this to be meaningful might be somewhat subjective, although measures already exist for Vigor (NPP, NCP) and Organization (diversity indices). Since resilience is only one form of stability, that component should be an additive function.

The basic medical definition of health used to be freedom from disease. Part of a new definition is resilience to stress<\‹>of course, there is good stress (eu-stress) as well as bad stress. Ecosystems respond to stresses in different ways, but usually through a decrease in productivity and material uptakes. Stress may be related to the rate of change for the system, in addition to loss or gain of components or changes in structure.

Jay OLaughlin et al. defined forest health as the capacity for self-renewal, the ability to recover from stress and disturbance, natural and human-caused. He also defined it a year later (1994) as a "condition of forest ecosystems that sustains their complexity while providing for human needs." Or, in an expanded definition: "the vigor or vitality of interacting biotic and abiotic elements of a system characterized by extensive tree cover that function together to sustain life and are isolated mentally for human purposes."

Vitality can include pests and thinning. As a forest ages, it thins itself naturally. The number of trees decrease as the stand ages; the remaining trees are typically bigger. As the frequency of disturbance increases, the forest becomes adapted to the disturbance<\‹>even pine plantations in the southeastern US that are managed with controlled burns are less damaged by cool wildfires; after long periods without disturbance, a catastrophic disturbance is more likely<\‹>where wind and fire are absent, the probability of insect and disease outbreaks increases. Yet, even catastrophic disturbances like hurricanes rarely damage more than 5 percent of a forest. More than being agents of mortality, insects, diseases, and animals are native components of complex food webs in ecosystems that contribute to the selection of certain kinds (including healthy) and ages of trees (that determines the composition of the forest, which changes over time). Mammals and birds disseminate seeds. Insects pollinate some trees and overwhelm others (rarely more than 1 percent of a forest). Diseases remove stressed trees (also probably a low percentage on the order of 1 percent). Their effect on the long-term health of a forest can only be regarded as positive.

A healthy forest is flexible in its response to diseases and pests. Most healthy ecosystems have high degrees of flexibility. As Gregory Bateson interprets Ross Ashby, any biological system can be describable in terms of interlinked variables, each of which has an upper and lower threshold of tolerance, beyond which the system acts pathologically. Within the limits the variables can be moved for the system to be adapted to the environment. Under stress, some variables move to maximum values near the upper or lower limits--the system loses flexibility, that is the "uncommitted potential for change" (Batesons definition), and can be destroyed by further stress. The danger in each case is working near the maximum of the system. In the case of forestry, we and our civilizations are part of the system. If an overpopulated society wants more forest products for houses, furniture, and fuel to be more comfortable in an overpopulated state, then more trees must be cut, and this, because the variables are interlinked, means that the stress spreads to more forests. To keep ecological flexibility in the forests, for forest health, wood resources would have to be budgeted in appropriate ways, or demand would have to be reduced--or forests would have to be expanded.

Signs of ecosystem health include the homeorhesis of the system (a similarity of flow, rather than the stable state of homeostasis, after Waddington), the stability of the system (that is, its resilience after stress, such as floods), the diversity of its components, the continuous recycling of elements, and flourishing. Health is the overall ability of a system to maintain itself under a normal range of environmental conditions (which may include hurricanes, volcanic eruptions, or fires). Obviously, a pioneer community may change the conditions to favor a new level of the system with new components.

Using a concept of forest health as persisting within certain boundaries, but varying periodically or aperiodically within those boundaries, management is concerned with actions that might kick the system out of bounds. Furthermore, as an historical process the forest can be considered as having a trajectory

In a living system, nothing keeps growing forever; things die and are reborn in cycles. The continuation of the system depends on these cycles. The cycles are bound by limits. Both individuals and communities are usually bound by one or two specific limits. Ecosystem health occurs within those limits.

It is quite likely that harvesting a limited number of trees in a predominantly natural forest could reduce the probability of disturbance as well as stimulate new growth, although it may equally possible that the regular removal of trees for human use may result in the gradual and long-term decline of a forest. One task of ecoforestry is to allow natural agents to average out and to minimize human disturbance that could destroy the health of a forest.

Reconsiderations of Redefinitions
With a focus on the size and growth rate of stems as log units, many other forest measurements are ignored: shrubs, forbs, ratios of shrubs and forbs to trees, biodiversity, soil depth and dynamics, direction of succession, very-long-term biological processes, carbon loss or gain, biomass (R. Margalef suggests that an objective of an ecosystem is to maximize biomass), and the role of forests in the biosphere cycles.

Monitoring is crucial to understanding forests. Until we understand how forests change and move around the landscapes, we will not know which changes are important and inevitable and which are the unhealthy result of human interference. Until we understand the changes, we will not be able to adjust our needs to the limits of forests.

Richard Harts approach to monitoring is based on his observations: "The actual substance of which the forest environment is made consists of patterns rather than things or individual species. The forest environment is generated by a patterning of ecological ebb and flow of energy, substances, individuals and species across a suitable landscape. The distinction between growing and declining patterns is not arbitrary, and can be arrived at objectively."

Hart suggests comparing current patterns with historic patterns. Monitoring for elements of the patterns will reflect their changes in distribution and abundance. A list of the most important variables or indicators is made, including compaction, stream chemistry, landscape morphology, and atmospheric.

Descriptions of each indicator outline the specific attributes which can be measured, as well as an explanation of why they contribute to our understanding of forest health. It is anticipated that as understanding of ecological processes increases the number and type of indicators may change.

Before monitoring can begin the objectives and data collection methods have to be nailed down. The purpose of the monitoring program has to be stated; the objectives have to be identified, e.g., the health of the forest. Health will probably be the first objective, followed by production or aesthetics. Health can be "defined" by a set of indicators of health, such as species, or patterns of health, such as stability or productivity. None of the indices that are measured are really adequate to define the health of the forest because they cannot account for the complexity, richness, and cycling that goes on in the forest. For that reason health indices are data that need to be resolved on the ground in person by someone who knows the history of the forest and has a feel for it.

Descriptions of historic landscape disturbance regimes (e.g., fire magnitude and frequency) and the ecosystem component patterns they maintained (e.g., vegetation composition) provide an initial template for descriptions of ecosystem health. The procedural consequences of these facts involve practical changes in the ecosystems collective patterning of shared needs and governance which can be defined as its health or soundness.

Monitoring facts and connections is important because it references the ultimate intent of ecosystem management: To discover and describe the structural correspondence between a species and its environment. A healthy species not only fits its environment well but also defines or clarifies the collective life it adapts to. We perceive this clarity to be the richness and wholeness of ecosystem structure. An unhealthy or absent species confuses the collective life, and we perceive this as static, fragmented or degenerating environment. There is a correspondence between the holistic behavior of a species and how it can be seen to relate to other elements of the ecosystem.

The trees and other plants and animals evolve into a community of thousands of different species. The "checks and balances" of a complex number of predators, prey, and decomposers tends to dampen any one species from getting out of control (and becoming a pest). This is not to say that everyone lives in a disneyesque fantasy of good will. Organisms survive by defending themselves or attacking others. But, the defensive and attack strategies "coevolve" (Ehrlich and Ravens term) over time. Organisms specialize to avoid competing. Relationships become more intimate, as organisms cooperate for survival advantage and strive for efficiency.

Efficiency has real social and ecological limits. Mechanical efficiency is a small subset of the kinds of efficiency that need to be cultivated. Noss and others have noted that maintaining a healthy forest ecosystem is more efficient in the long-run than having to duplicate the forest functions to keep it healthy. Furthermore, it is dangerous to take maximum yields out of a system unless all factors are known--a virtual impossibility. Therefore, we must aim for optimum yields and calculate (and hope) that the forest has sufficient flexibility to recover from our "take."

Data sorts itself into description by patterns and rules--this is the essence of fuzzy systems. More data results in more patterns and more rules, up to a point, then the rules sort of "max out." A washing machine may only need 30 rules to deal with load size, water cleanliness, but rules for forest management may number 500; maybe 300 or 8000, we will not know until we try. It would require monitoring thousands of parameters and then creating rules to deal with them. Parameters could include canopy cover, stream flow, number of fungus species, number of food webs, or age. The rules would then dictate how much to cut or not cut or whether to cut at all. Cutting would be adjusted based on canopy, water retention (date of snow melt), floor temperature, humidity, and other factors. The rules could also track and evaluate the health of the forest. We could relate patterns in general using a fuzzy model.

Redefinition: Health as Harmony and Wholeness
Health is the coherence of the pattern of living in other words. If the pattern is disrupted, the local entity dies. Many local patterns flow together through time interdependently, sharing materials. The death of one pattern sometimes leads to the death of other patterns. The body of a human or forest or any entity is a dynamic pattern supported by dynamic processes that include other entities.

In Chinese medical tradition, the highest good is harmony, especially social harmony, or good relations. A good person is one who creates and maintains harmony. Perhaps this is the best working definition of health.

Furthermore harmony is related to wholeness. The word "whole" comes from the Indo-European root kailo, which is also the root for the words health and holy. The concept of the whole forest. A forest that has very complete complement of interacting beings. A whole forest can renew itself without replanting and pesticides.

David Bohm, in his theory of the implicate universe, proposes that health is a result of a harmonious interaction of all the analyzable parts that comprise the extricate order--cells, tissues, organs, the body--with the surrounding larger environment. Health is a quality that is grounded in the total order of the environment (or implicate order). Health is a dynamic quality of the entire movement of the environment (holoverse) as it flows. As organisms sometimes interfere with others or with the flow of change, the harmony breaks down--we call that disease. Health is the dance of bodies that interpenetrate (in Paul Shepards image).

None of the bodies are completely independent or completely bounded; they are interdependent and open systems. A body is only maintained by a flow of energy and materials from its environment--much of this flow is in the form of other entities, usually much smaller, such as prey, insects, bacteria, viruses.

Now we can address health in forests, which are larger entities made up of other beings--large patterns made up of smaller ones. The forest is a constant where every component changes, disappears and appears. It is a pattern like a whirlpool. The pattern forms from a torrent of light, energy, molecules, air, water, and even bigger things.

Comprehending patterns is necessary to protect the scale of the forests that is too large to see (watersheds, except by satellite), the parts of the forest that are too small to see (fungi and viruses), the parts that are too-long-lived for us to observe (long successional changes or evolutions), and the parts that we are ignorant about. Without special effort, we are aware only of what we see working in the forest during a very short time. We trust that our plans will ensure that the forest will remain as a healthy entity for a very long time so that many generations of us can gather our needs from it.

Summary
At an SAF meeting last month in California, the body of foresters indicated that the regional group should pursue developing a definition of a healthy forest, which they could use to evaluate certification programs.

Historically, we have used forests without regard to their continuity or to their health. Partial knowledge and technology has allowed us to exploit our environment beyond what is desirable for us or for other species. While continued, moderate exploitation is necessary to live, too much exploitation is unwise. A wise use of resources would not make the world less habitable. We are part of the system and must protect its health as a whole.

More than being just a crisis science, ecoforestry is a medical discipline, aimed at restoring forests to health. As with any medicine, the patient actually does most of the work to become healthy, although the doctor gets the credit and the payment. This would also lead to more respect for the practitioners, but also to more responsibility and more rules. The first rule, which we might take to be basic, is identical to the first vow of the Hippocratic oath, "Do no harm" (see Ecoforesters Oath). Noninterference is a basic ecoforestry principle--do not interfere with the health and stability of the forest--the health, diversity, and stability of the forest are a first consideration.

Ecoforestry is a maturing stage that bases forestry in a community context and limits the use of the forest to that which the forest can afford to provide and remain healthy. Ecoforestry undertakes the responsibility to preserve the healthy functioning of the forests under its domain. Ecoforestry has a responsibility for the ecological production of goods from a forest. The health of ecosystems and human institutions should be measured with a holistic index. We have not developed qualitative indicators of ecological health or quantitative measures of social health, much less an ecocentric view that would value preserves of nature for themselves.

To address the health of forests by ecoforestry would be a temporary medicine, not a constant intervention or even a continuous diet. We have already tried to gain complete control over forests through scientific methods and technological applications. We regard medicine as a foolproof system that tried to eliminate weakness, disease, and mistakes.

Rather than telling the forests what to do, rather than controlling their growth, we need to watch forests to see what they do (this used to be the function of natural history), and we need to let them do it (this requires patience and temperance). Abraham Maslow regards this attitude as "taoistic," and the way to forest health is letting the forest do most of the choosing and working.

Our response to the forest, being concerned with its health (as forest doctors or nurses perhaps), is not benign neglect or complete anticipatory stewardship, it is participation in the process of the forest as a harmonious system, with mutually restrained conflicts and constrained influences. The goodness of our lives reflects an imperfect balance of love and selfishness, reason and passion, sensuous materiality and spirituality. We have the responsibility to be healthy, to contribute to the health of our community, and to contribute to the health of natural forest communities.

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