by MrBean » Tue 24 Jun 2008, 19:35:13
$this->bbcode_second_pass_quote('AlterEgo', '')$this->bbcode_second_pass_quote('MrBean', '')$this->bbcode_second_pass_quote('', '
')Unfortunately, that evolutionary technique of many seeds is not as successful in a climax culture with limited resources.
Huh? Please explain.
Sorry, Mr. Bean. I was using shorthand speech, and did not explain myself fully. I like how the Archdruid explains successional communities below.
$this->bbcode_second_pass_quote('', '"')One ecological pattern that deserves especially close attention as we begin the long slide down the back end of Hubbert’s peak is the process called succession. Any of my readers who were unwise enough to buy a home in one of the huge and mostly unsold housing developments cranked out at the top of the late real estate bubble will be learning quite a bit about succession over the next few years, so it may be useful for more than one reason to summarize it here.
Imagine an area of bare bulldozed soil someplace where the annual rainfall is high enough to support woodland. Long before the forlorn sign saying “Coming Soon Luxury Homes Only $450K” falls to the ground, seeds blown in by the wind send up a first crop of invasive weeds. Those pave the way for other weeds and grasses, which eventually choke out the firstcomers. After a few years, shrubs and pioneer trees begin rising, and become anchor species for a young woodland, which shades out the last of the weeds and the grass. In the shade of the pioneer trees, saplings of other species sprout. If nothing interferes with the process, the abandoned lot can pass through anything up to a dozen different stages before it finally settles down as an old growth forest community a couple of centuries later.
This is what ecologists call succession. Each step along the way from bare dirt to mature forest is a sere or a seral stage. The same process shapes the animal population of the vacant lot, as one species after another moves into the area for a time, until it’s supplanted by another better adapted to the changing environment and food supply. It also proceeds underground, as the dizzyingly complex fabric of life that makes up healthy soil reestablishes itself and then cycles through its own changes. Watch a vacant lot in a different ecosystem, and you’ll see it go through its own sequence of seres, ending in its own climax community — that’s the term for the final, relatively stable sere in a mature ecosystem, like the old growth forest in our example. The details change, but the basic pattern remains the same.
Essential to the pattern is a difference in the way that earlier and later seres deal with energy and other resources. Species common in early seres – R-selected species, in ecologists’ jargon – usually maximize their control over resources and their production of biomass, even at the cost of inefficient use of resources and energy. Weeds are a classic example of R-selected species: they grow fast, spread rapidly, and get choked out when slower-growing plants get established, or the abundant resources that make their fast growth possible run short. Species common in later seres – K-selected species – maximize efficiency in using resources and energy, even when this means accepting limits on biomass production and expansion into available niches. Temperate zone hardwood trees are a classic example of K-selected species: they grow slowly, take years to reach maturity, and endure for centuries when left undisturbed.
Apply the model of succession to human ecology and a remarkably useful way of looking at the predicament of industrial society emerges. In successional terms, we are in the early stages of the transition between an R-selected sere and the K-selected sere that will replace it. The industrial economies of the present, like any other R-selected sere, maximizes production at the expense of sustainability; the successful economies of the future, emerging in a world without today’s cheap abundant energy, will need to maximize sustainability at the expense of production, like any other K-selected sere.
To put this into the broader picture it’s necessary to factor in the processes of evolutionary change, because climax communities are stable only from the perspective of a human lifetime. Environmental shifts change them; so, often on a much faster timescale, does the arrival of new species on the scene. Sometimes this latter process makes succession move in reverse for a while. For example, when an invasive sere of R-selected species outcompetes the dominant species of a K-selected climax community; eventually the succession process starts moving forward again, but the new climax community may not look much like the old one.
Apply this to the human ecology of North America, say, and it’s easy to trace the pattern. A climax community of K-selected Native American horticulturalists and hunter-gatherers was disrupted and largely replaced by an invasive sere of European farmers with a much more R-selected ecology. Not long after the new community established itself, and before succession could push it in the direction of a more K-selected ecology, a second invasive sere – the industrial economy – emerged, using resources the first two seres could not access. This second invasive sere, the first of its kind on the planet, was on the far end of the R-selected spectrum; its ability to access and use extravagant amounts of energy enabled it to dominate the farming sere that preceded it, and push the remnants of the old climax community to the brink of extinction.
Like all R-selected seres, though, the industrial economy was vulnerable on two fronts. Like all early seres in succession, it faced the risk that a more efficent K-selected sere would eventually outcompete it, and its ability to use resources at unsustainable rates made it vulnerable to disruptive cycles of boom and bust that would sooner or later guarantee that a more efficient sere would replace it. Both those processes are well under way. The industrial economy is well into overshoot at this point, and at this point a crash of some kind is pretty much inevitable. At the same time, the more efficient K-selected human ecologies of the future have been sending up visible shoots since the 1970s, in the form of a rapidly spreading network of small organic farms, local farmer’s markets, appropriate technology, and alternative ways of thinking about the world, among many other things."