From: All Relationships Are Self-Reinforcing Feedback Loops
By Chris Maser | March 14, 2011
Everything in the universe is connected to everything else in a web of interactive feedback loops, all found in self-reinforcing relationships that create new, never-ending stories of cause and effect. Everything, from a microbe to a galaxy, is defined by its shifting relationship to every other component of its environment. Every relationship illustrates the flow of energy and cycling of matter—the dynamic that moves all systems.
A feedback loop is a relationship between energy moving through matter that causes an outcome. 1 Humans often have definite desires where outcomes are involved and value some outcomes more than others. A simple example might be the response of North American elk in the Pacific Northwestern United States to changes in their habitat. In this case, the competing values are: elk as an economically important game animal versus timber as an economically important commodity.
In the 1940s and 1950s in western Oregon, the timber industry often used the adage: good timber management is good wildlife management. At the time, that claim seemed plausible because elk populations were growing in response to forests being clear-cut. By the mid-to-late 1960s and throughout the 1970s, however, elk populations began to exhibit significant declines. Although predation was presented as the obvious reason, it did not hold up under scrutiny since the large predators, such as wolves and grizzly bears, had long been removed and the mountain lion population had been decimated because of the bounties placed on the big cats.
As it turned out, the cause of the decline in elk numbers was subtler and far more complicated than originally thought. The drop in elk numbers was in direct response to habitat alteration by the timber industry. This is not surprising since elk, like all wildlife, have specific habitat requirements that consist of food, water, shelter, space, privacy, and the overall health of the habitat. When any one of these elements is in short supply, it acts as a limiting factor or constraint to the ability of a species’ population to maintain equilibrium.
In the early days before extensive logging began, the land was well clothed in trees, making food the factor that limited the number of elk in an area. As logging cleared large areas of forest, grasses grew abundantly. Elk, being primarily grazers, became increasingly numerous. This relationship continued for some years, until—for an instant in time—the perfect balance between the requirements of food and shelter was reached. The proximity to water did not play as important a role in this balance because of the relative abundance of forest streams and because elk can travel vast distances to find water. Thus, hunters and loggers initially thought clear-cut logging as the proverbial win-win situation (a positive, self-reinforcing feedback loop).
But as it turned out, the conflict for the elk was between food and shelter. At first, food was the limiting factor because elk were constrained in finding their preferred forage by the vast acres of continuous forest. Logging started to shift the habitat in a way that proved detrimental to the elk because, while the amount of food increased, the amount of shelter declined disproportionately. The shelter once provided by the forest became the factor that increasingly reversed the elk’s growth in numbers. Here, it must be understood that shelter for elk consists of two categories—one for hiding in the face of potential danger (simply called hiding cover) and one for regulating the animal’s body temperature (called thermal cover).
Thermal cover often consists of a combination of forest thickets or stands of old trees coupled with topographical features that block the flow of air. Thermal cover allows the elk to cool their bodies in dense shade in summer and get into areas of calm, out of the bitter winds in winter, that reduces the wind-chill factor and thus conserves their body heat.2 Hunters began to see the systematic, widespread clear-cutting of the forest as a losing situation for huntable populations of elk (a negative, self-reinforcing feedback loop), although they did not equate the loss of thermal cover as the cause.
http://www.greenconduct.com/blog/2011/03/14/principle-6-all-relationships-are-self-reinforcing-feedback-loops/
ENDNOTES
1. Chris Maser. Earth in Our Care: Ecology, Economy, and Sustainability. Rutgers University Press, Piscataway, New Jersey. (2009) 262 pp.
2. The discussion of elk is based in part on Jack Ward Thomas, Hugh Black, Jr., Richard J. Scherzinger, and Richard J. Pederson. Chapter 8, Deer and Elk. Pp. 104-127. In: Wildlife Habitats in Managed Forests: The Blue Mountains of Oregon and Washington. Jack Ward Thomas (Technical Editor). U.S. Department of Agriculture, Forest Service, Pacific Northwest Range and Experiment Station, Portland, Oregon. Agricultural Handbook No. 553. 1979.
3. David Archer. Carbon Cycle: Checking the Thermostat. Nature Geoscience, 1 (2008):289-290
4. Richard E. Zeebe and Ken Caldeira. Close Mass Balance of Long-Term Carbon Fluxes From Ice-Core CO2 and Ocean Chemistry Records. Nature Geoscience, 1 (2008):312-315
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