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~ Wednesday, January 11 ~
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weeds

These days, wilderness is found where the weeds are. This is because cityscapes, nature reserves, fisheries - ecosystems generally - are increasingly being managed (farmed?) for the benefit of humans. Wikipedia says that “a weed is a plant in an undesired place”. But who judges desirability? Basically weeds are “unwanted plants in human-controlled settings” that grow and reproduce aggressively. Is there anywhere on the planet that is not human controlled? In his discussion of  how satellites end ‘nature’, McLuhan says no. Nature reserves and national parks are human controlled because they usually involve management of invasive species and predators.

What will happen when people stop weeding out the weeds? Humans don’t have a snowball’s chance of managing a global ecosystem of rampant invasive speciation. The world’s ecosystems have been  permanently altered on a large scale since the introduction of farming about 8,000 years ago, and particularly rapid change has occurred since the industrial revolution in the last couple of centuries. The genie is out of the bottle. Global ecosystems are now on a different trajectory, charting new territory. 

David Quammen has written an awesome article about this called Planet of Weeds. Here is a summary - which states:

"There have been five major extinctions in earth’s history and it appears that we are currently entering a sixth. The difference between the current mass extinction and those that preceeded it is that this one is human-caused; the five major threats to biodiversity being habitat destruction, habitat fragmentation, overharvesting, invasive species, and cascading secondary effects resulting from disruption of ecological connections. At the root of these problems is human population expansion, a problem which is itself complicated by the widening wealth gap between the developed and the developing nations. The biological consequence of this extinction is very likely to be that we will live in a world populated by weedy species. Loss of biodiversity and proliferation of weedy species will degrade ecosystem services and eliminate biological resources; in combination with population pressures, this will result in a far less pleasant, more stressful, and uglier world.”

The struggle between wilderness (uncontrollable nature) and management (appropriation of resources for human use) is leading to a wilderness of weeds. This is the outcome of attempting to dominate ‘nature’ (or wilderness) for 8,000 or so years, because domination has lead to the eradication of what is not wanted, generating a mass extinction which leaves ecosystems incomplete and weak, providing plenty of opportunities for invasive species to spread. We’d better get used to weeds, they will be our bread and butter in the future.

image

Gorse in Aotearoa / New Zealand

The summary of Planet of Weeds omits Quammen’s wonderful way with words as he draws readers into his grim tale. There is a lot in the article, so a number of standout sections have been cut from the original article and pasted below to generate an extended summary of sorts. The idea is that these paragraphs are here, waiting to be discussed further some other day…

"Hope is a duty from which paleontologists are exempt… they’re the coroners of biology"

"Some people will tell you that we as a species, Homo sapiens, the savvy ape, all 5.9 billion of us in our collective impact, are destroying the world. Me, I won’t tell you that, because “the world” is so vague, whereas what we are or aren’t destroying is quite specific.”

"Some people say that the environment will be the paramount political and social concern of the twenty-first century, but what they mean by "the environment" is anyone’s guess. Polluted air? Polluted water? Acid rain? A frayed skein of ozone over Antarctica? Greenhouse gases emitted by smokestacks and cars? Toxic wastes? None of these concerns is the big one, paleontological in scope, though some are more closely entangled with it than others."

[I love what Quammen says here about ‘the environment’. It is a particular bugbear of mine that people in advertising often say that if you buy a particular product you will be ‘helping the environment’. What does that mean? Does ‘the environment’ need help? I don’t think so - it is people that need help.]

"How many protected areas will there be? The present worldwide total is about 9,800, encompassing 6.3 percent of the planet’s land area. Will those parks and reserves retain their full biological diversity? No. Species with large territorial needs will be unable to maintain viable population levels within small reserves, and as those species die away their absence will affect others. The disappearance of big predators, for instance, can release limits on medium-size predators and scavengers, whose overabundance can drive still other species (such as ground-nesting birds) to extinction. This has already happened in some habitat fragments, such as Panama’s Barro Colorado Island, and been well documented in the literature of island biogeography. The lesson of fragmented habitats is Yeatsian: Things fall apart."

"We shouldn’t take comfort in assuming that at least Yellowstone National Park will still harbor grizzly bears in the year 2150, that at least Royal Chitwan in Nepal will still harbor tigers, that at least Serengeti in Tanzania and Gir in India will still harbor lions. Those predator populations, and other species down the cascade, are likely to disappear. "Wildness" will be a word applicable only to urban turmoil. Lions, tigers, and bears will exist in zoos, period. Nature won’t come to and end, but it will look very different."

"What do fire ants, zebra mussels, Asian gypsy moths, tamarisk trees, maleleuca trees, kudzu, Mediterranean fruit flies, boll weevils and water hyacinths have in common with crab-eating macaques or Nile perch? Answer: They’re weedy species, in the sense that animals as well as plants can be weedy. What that implies is a constellation of characteristics: They reproduce quickly, disperse widely when given a chance, tolerate a fairly broad range of habitat conditions, take hold in strange places, succeed especially in disturbed ecosystems, and resist eradication once they’re established. They are scrappers, generalists, opportunists. They tend to thrive in human-dominated terrain because in crucial ways they resemble Homo sapiens: aggressive, versatile, prolific, and ready to travel. The city pigeon, a cosmopolitan creature derived from wild ancestry as a Eurasian rock dove (Columba livia) by way of centuries of pigeon fanciers whose coop-bred birds occasionally went AWOL, is a weed… In gardening usage the word “weed” may be utterly subjective, indicating any plant you don’t happen to like, but in ecological usage it has these firmer meanings. Biologists frequently talk of weedy species, meaning animals as well as plants.”

"Do you see Homo sapiens as a likely survivor, I ask him or as a casualty? “Oh, we’ve got to be one of the most bomb-proof species on the planet,” he says. “We’re geographically widespread, we have a pretty remarkable reproductive rate, we’re incredibly good at co-opting and monopolizing resources. I think it would take really serious, concerted effort to wipe out the human species.” The point he’s making is one that has probably already dawned on you: Homo sapiens itself is the consummate weed. Why shouldn’t we survive, then, on the Planet of Weeds? But there’s a wide range of possible circumstances, Jablonski reminds me, between the extinction of our species and the continued growth of human population, consumption, and comfort. “I think we’ll be one of the survivors,” he says, “sort of picking through the rubble.” Besides losing all the pharmaceutical and genetic resources that lay hidden within those extinguished species, and all the spiritual and aesthetic values they offered, he foresees unpredictable levels of loss in many physical and biochemical functions that ordinarily come as benefits from diverse, robust ecosystems—functions such as cleaning and recirculating air and water, mitigating droughts and floods, decomposing wastes, controlling erosion, creating new soil, pollinating crops, capturing and transporting nutrients, damping short-term temperature extremes and longer-term fluctuations of climate, restraining outbreaks of pestiferous species, and shielding Earth’s surface from the full brunt of ultraviolet radiation. Strip away the ecosystems that perform those services, Jablonski says, and you can expect grievous detriment to the reality we inhabit.”

"Still, evolution never rests. It’s happening right now, in weed patches all over the planet. I’m not presuming to alert you to the end of the world, the end of evolution, or the end of nature. What I’ve tried to describe here is not an absolute end but a very deep dip, a repeat point within a long, violent cycle. Species die, species arise. The relative pace of those two processes is what matters. Even rats and cockroaches are capable—given the requisite conditions; namely, habitat diversity and time—of speciation. And speciation brings new diversity. So we might reasonably imagine an Earth upon which, 10 million years after the extinction (or, alteratively, the drastic transformation) of Homo sapiens, wondrous forests are again filled with wondrous beasts. That’s the good news.”

Tags: david quammen invasive species planet of weeds wilderness urban ecology weeds 2012
38 notes  ()
  1. walkingfern reblogged this from mareephemerae
  2. simplelife62 reblogged this from mareephemerae and added:
    Pretty long but worth reading imo.
  3. mareephemerae posted this