RELILIENCE AND HUMAN ACTIVITY

Biodiversity has been reduced more in this century than at any time in history, fossil or human. Human activities have been at least a hundred times more disruptive than any catastrophe we have imagined. At the same time, the human population growth has accelerated at a staggering pace (Table 1).

As humans, we might imagine a local loss of carrying capacity when some disaster destroyed significant watersheds, and insufficient fresh water was available for human use in drinking, irrigation, and industry. Loss of the watershed has been convincingly related to the demise of several human civilizations over the past 5,000 years (Ponting,1991). We remain dependent on rainfall and snowmelt for most of our fresh water in Texas even today. However, rainfall also causes floods, and destroys watersheds, particularly when they are already damaged. Along with the flood damage, valuable topsoil is lost as well, which is a non-renewable resource for practical purposes. In 1993 the US along the Mississippi and Missouri rivers suffered this fate. However, individually we also are much more "hazardous to the ecosystem's health" than most of us realize, simply by living our day-to-day life.

More than 99% of the world's food supply comes from the land, and 97% of the world's liquid fresh water supply is below the surface. Both the productivity of the land and the infiltration of water depends on healthy soils, high in organic matter. Organic matter depends upon high biodiversity above and below the surface.

Most of our lifestyle greatly erodes the carrying capacity of our ecosystem. If we were to write a Lifetime Environmental Impact Statement for each child born in Texas today, it would have the following features:

• production of 2.2 million pounds of solid wastes (14 railway cars)
• production of 2.2 million pounds of atmospheric wastes
• production of 22 million pounds of liquid wastes (~3 million gallons)
• will consume 1.54 million pounds of minerals
• will use 24 billion BTUs of energy, equivalent to 4000 barrels of oil
• will eat 56,000 lbs of animal products, provided by 2000 slaughtered animals (most fed a ration high in grain)

Biodiversity is correlated with ecological stability because the flow of resources from one species to another has many branches, and many feedback regulation modes. Biodiversity implies much more than a collection of species. Resilience is the property of a system to recover from disturbance, which in turn is closely related to natural, co-evolved biodiversity. There are sometimes "keystone" species that fill a central role in the local ecological system, but we often do not recognize these species. We generally know very little of the ecological system. When we find them, we can use this information of how the community is organized to great benefit.

Although we have accomplished many technological miracles, we remain totally dependent upon the ecosystem for our water, air, and food. These essentials of life have been modified, reduced and enhanced by our technology, but never replaced. They have become a part of our background awareness to a large degree, and we fail to realize the threats of our shocking, our disrupting the functionality, of our ecosystem. We are taking advantage of the resiliency of the ecosystem, while we are simultaneously reducing the resiliency. Conservation of the functionality of the ecosystem is essential for maintaining the resource base of life, and our options to experiment with it.

POINTS OF VIEW

We have two points of view of how the ecosystem is organized. The prevalent point of view is that the ecosystem is complex, but with somewhat interchangeable components. Generally speaking, we may find different species or cultural practices to fill some essential role in the system's function when part is absent, such as domesticated animals substituting for wildlife, or tillage substituting for earthworms. In fact, through research and cleverness we perceive that we may improve the original system by substituting improved replacements for existing parts.

For example, we may engineer more efficient cows for producing milk, or chickens to lay more eggs, or plants with increased photosynthesis. If we have an insect pest develop (a species with a tendency for its population to expand to economically harmful levels) we may reduce the size with a pesticide, or with biocontrol through the introduction of a particular "beneficial" insect. We rely on extensive research on particular components of the system to direct our plan of control. However, we disregard the fact that the vast majority of the components are unidentified, and incredibly little is known about the relationships among even the known components.

The second point of view is much less prevalent, but is becoming more respected among many managers of biological resources. It is the view that there are integrated wholes that function as a unit, almost like an organism, and these wholes are functioning parts of larger wholes. The proponents of this point of view have observed the incapability of most models to predict ecological outcomes, even for a short span of time. Also, the expected responses, even when partially realized, are accompanied by many others that were not expected, some with considerable delays. Management of wholes is accomplished by taking cautious action based on ecosystem functions, and watching carefully for the results. Rather than addressing particular problems, the focus is on broader systems in the ecosystem, such as increasing ground cover, recovery of vegetation, infiltration of water, and the presence of beneficial insects. Management is a series of steps, each taken with an expectation of unexpected results. Changes in management plans are frequent, adjusting to the actual results that occur. This is called adaptive management, or holistic management. It requires both skill and good observation.

Both of these points of view may be used effectively, but in different contexts. Our scientific activities require simplicity in the experimental design, or in the theoretical models we use as generalizations. The first perspective is well suited to that activity. However, management always involves a unique situation. (The history of any given parcel of land, or human enterprise has particular unique features that cannot be repeated.) Generalizations of management actions are inappropriate, and only mid-course corrections can be made in the context of particular conditions, with particular options, if the future results are to approach our goal. The second perspective becomes essential for management of wholes, since we are not "playing the odds" as we do in scientific modeling and judging the degree of theory's power. A manager realizes that, while they may apply only one tool, or take only one action, it is impossible for them to have only one effect. They cannot address only one problem at a time. They can only affect the system, which changes many relationships sooner, and many more later.

EXAMPLES OF HOLISTIC MANAGEMENT

The Maddox Ranch, near Colorado City, Texas, in 1986 supported 4 people comprising 2 families with great financial insecurity. The ranch supported 1 animal per 29 acres for a year, on the average. The ranch was $4 million in debt. (Figure 1) I met the Maddox family in 1986, and they were desperate to improve their finances, their quality of life, and the productivity of their ranch. They had come to learn about holistic management.

This ranch in 1994 had accomplished the impossible. It now supported 14 people, comprising 5 families with a high quality of life. There were only 15 acres needed to support 1 animal a year, and they were debt free. The change was one of management style, and the perspective was one of functioning wholes in the ecosystem, nested within greater wholes. They monitored carefully how the species complexity increased with respect to vegetation and wildlife, and how the water table rose. They had springs that once again flowed year-round after they had been dry for almost a century.

The Maddox family did not manage for these changes specifically. They did not plant any seed or plow the soil to increase infiltration. Instead they used their animals to create a high concentration of fresh manure in areas with little vegetation, and increased vegetative litter by feeding hay in these areas in the winter. They moved their animals so that they were grazing only a small part of the ranch briefly, but with several months during which each part was rested from grazing. They found that water infiltration increased to an "alarming" rate, when the water level in their ponds failed to increase after rains. However, with great relief they saw their springs return and the perennial flow of water not only supplied the needs for their animals, but brought new habitats for fish and riparian plants and animals. Big bluestem, a high quality grass typically found further east with higher rainfall, began to grow from the water of the riparian area, expanding over the hillside. The seed came from hay fed upstream, and fared well as the quality of the soil improved (Figure 2).

The Mesquite Grove Ranch, near Snyder, Texas, in 1989 began to change the way they managed also. They monitored the amount of exposed soil between grass plants. They grazed their pastures in a similar fashion to the Maddox family. They also measured the changing species composition over the following several years. An interesting combination of changes resulted (Figure 3).

For three years there was little change in the amount of exposed soil, and there were few perennial species of grass. However, in the fourth through sixth years, the exposed soil declined abruptly, and the percentage of perennial species of grass increased around 10-fold. The management was not specifically to accomplish this change, but was to promote growth of any species that provided soil cover, and to promote the root development of these species by their planned grazing, using high animal density applied in short pulses, and careful timing of grazing and recovery matched to the features of the vegetation. Livestock grazing was brief but intense, with extensive periods allowed for plants to recover. It was observed that new seedlings appeared, and then the perennial species began to dominate since they recovered faster from grazing. The biodiversity of the vegetation and soil increased. Earthworms appeared and springs resumed or increased flow as the water table rose. What water did not soak into the ground carried little sediment, indicating rapid infiltration, and slow runoff. Figure 4 shows two bottles of water. The one on the left was at the upstream ranch border, with a load of sediment. The one on the right is clear, and is representative of any sample taken on the ranch.

MANAGING ECOSYSTEM PROCESSES

These ranchers were not managing particular components of their ranch ecosystem as one would do from a common perspective of the ecosystem. They did not assume that they could select the "best" species of vegetation, or that they could increase water infiltration with a mechanical treatment of the soil. Instead, they used the animals differently, and watched what changes occurred in the processes acting in the ecosystem, or watched certain features that they knew would reveal changes in the general nature of the ecosystem. They knew that exposed soil was subject to erosion, and could not transform sunlight and carbon dioxide into living material. So, they did whatever they could to encourage plant growth. Seedlings appeared where the livestock left dung, and passage of the animals planted seed in shallow footprint pockets. However, they were careful to avoid compaction of the soil by timing the animals' presence on a particular part of the land. When they found the results that increased life, they continued. When they found a decrease in life, they changed to new practices.

When one begins to bring life back to degraded grassland, there is a special role that the livestock and dung beetles play. There are several species of dung beetles, some that form a ball of dung about the size of a marble, and roll it away to bury ("tumble bugs") without interference from other beetles. Others dig deep tunnels under the pile of dung, and then take it down to form a ball. In all cases the female beetles lay a single egg in each ball of dung, which hatches and the larvae eats a hole in the ball, pupates a few days later, and emerge as adults after a few days more. Their exit tunnels to the surface leave an avenue for water to run into the soil when it rains, and the dung increases the organic matter deep in the soil. The combination of livestock, appropriately managed, with the dung beetles creates a rapid improvement in water infiltration and retention in the soil, and, eventually leads to the return of springs. Earthworms tend to follow this improved soil condition, and continue the beneficial effects. Livestock and dung beetles together might be considered a keystone combination for this ecosystem.

This picture shows a dung beetle "farm" made of plastic sheets about 1cm apart. On top of the soil is placed a generous supply of cow dung, known to be free of pesticides. Two pair of dung beetles were placed in the "farm" and began to dig their holes, plant their egg-bearing dungballs. In this picture there are over 70 dungballs, and each contains a larva. Note that the passage-ways extend the full depth of the soil, and one or more dungballs are found in each passageway. The beetles fill in the passageways, but after pupation the emerging beetles will dig out. From the surface we observe only the disappearance of the dung, but below the surface there are miraculous changes in soil porosity and organic matter. Imagine how the soil would be changed if there were 100 dung beetles or more – which is the ordinary situation for each pile of dung left by a cow when the weather is warm, and the beetles have not been poisoned.

IMPLICATIONS ABOUT RESILIENCEY, AND SUSTAINABILITY

Removal of bison in the areas of these two ranches caused a cascade of ecologically detrimental effects. The dung was gone, and the organic matter deep in the soil slowly began to decline. Cattle had been introduced, and during WW-I there was severe overgrazing, which changed the community of plants of deep-rooted perennial grasses supplemented by scattered wood perennial plants and seasonal annual plants. The new community became mostly seasonal annual plants with an increase in the woody perennials. The soil organic matter declined dramatically, and erosion began to increase. Infiltration to the water table (vadose zone) was reduced to almost nothing in most years. Although the cattle left dung, they were increasingly treated for internal and external parasites, some of which had part of their life cycle in the dung. Pesticides were introduced to control these parasites, and also reduced what dung beetles there were to marginal numbers. They were an "endangered species" without the label. The cost of these "treatments" to manage the ecosystem increased, and the productivity declined. Both economic health and ecological health suffered, while the entire time the managers were feverishly trying harder and harder to reverse the trends.

However, the knowledge of the system was inadequate, and the best of efforts tended to make matters mostly worse. Confidence in the degree of knowledge faltered, and, in desperation, a new perspective was tried.

Fortunately, the environmental resilience was great enough to offer responses with a change in management. The changes became the source of primary education in ecosystem dynamics. The management was more trial and error than using detailed scientific knowledge. The threat of bankruptcy forced a reduction in the reliance on purchased tools, so the degree of well meant but inappropriate ecosystem shocks was reduced. Because of the resilience in the ecosystem, the management changes manifested as improvements. Had there been insufficient resilience, the ecosystem may have continued it path to form a desert with little or no vegetation, leaving primarily bare rock on the surface.

Without reaching the stage of desperation quite as extreme as the Maddox family, the families at the Mesquite Grove Ranch also changed their form of management. Their profitability has steadily improved, while the ecosystem functions on their ranch improved. While information on the properties of "tools" from research tests is used and valued, the research focus of using a tool that is oriented to the solving of "a problem" is not part of their decision process. They view a tool as something that creates a general change in the relationships in the ecosystem system, and, when they decide to try a tool, the particular results that it produces are observed directly. These results may be similar to the research results, or those that are often seen on another ranch. However, there will be important unique results that were not found elsewhere, and would not even be expected on this ranch at another time or place. The guiding principle is that a promising tool may be tried, but it is realized that the "promise" is not the whole story. The guiding principle is to see if all of the effects are beneficial. Of course, this is never true, but each result is evaluated, and new action taken when the results are not beneficial. As a business, economics is a consideration. When an alternative tool is available without having to purchase it, it is selected first. This criterion also keeps the costs of operation low, and the production increases as the ecosystem functions more effectively. As dependency on resources from beyond the boundaries of the ranch is reduced, and as the use of native and renewable tools increases, the ranch becomes more profitable, more sustainable. They achieve a natural insurance from the increased resilience also.

We have much to learn from these examples, but more to learn from the concept of managing from a holistic perspective with the results dictating the changes in what we do. Theories, culture, and research must begin to play a subordinate role in management decisions, although they are never absent, nor should they be. As in the ecosystem, a balance is established in the management system between direct observation of what "works" and what we expect and wish to do. Anything which increases the resilience is insurance for a future, and thereby contributes to sustainability.

There are a number of examples in human history whereby cultures over-exploited their resources, and the society was lost in short order. The vegetation of much of the Mediterranean region once was mixed evergreen and deciduous forest. As it was cleared, overgrazing destroyed both the forest regrowth and quality grasses. This resulted in large scale erosion, forming large deltas and marshes in river mouths. Olive trees were introduced, since they were one of the few that could grow on such badly eroded lands. The deserts of North Africa once were fertile lands, destroyed by the demands for food in the Roman Empire (Ponting, 1991).

The more endangered species we have, the more striking the evidence that we are eroding resilience. We have other indicators as well, and all that I know have the same message. We are over- consuming our resources, whether by many mouths or by over-stuffed stomachs! Our environmental resilience is similarly declining, and our freedom to "experiment" is subtly being reduced. Will we become the global equivalent of North Africa?

Ponting, Clive. A green history of the world : the environment and the collapse of great civilizations. New York, 1991.

Pimentel, D., X. Huang, A. Cardova, M. Pimentel. 1996. Impact of population growth on food supplies and environment. Paper presented at the AAAS Annual Meeting, Baltimore, MD, 9 February 1996.

Published April 27, 1996.
File converted to HTML by SLC.