Life Webs


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Disturbances

This is a puzzle – a question, not an answer.

In our quest to heal the land – or our little piece of it, at any rate – my partner and I have been reading about permaculture and taking steps toward putting it into practice. We’ve planted ten fruit and nut trees to date, along with some berry bushes, and lots more are due to arrive this spring. We’re working on developing the “guilds” – assortments of plants to fill the other ecological niches – around them.

Permaculture (please excuse this abbreviated description of a very complex subject) is a way to accelerate the ecosystem succession (bare ground –> annual grasses –> perennials –> shrubs –> savanna –> climax forest) and then hold it at the savanna stage, which is considered the most varied and productive. At the moment, we’re working on hurrying along the bare ground and annual-grass areas and haven’t really dealt with the two-thirds of the land that is forested.

The name “permaculture,” and in fact the whole idea of sustainability, suggest that a balanced, self-equilibrating system is desirable and achievable. (Remember the “balance of nature” we learned about in school?)

But consider these quotes:

“Any level of secondary succession is determined by both those levels which precede and those levels which follow, the total ecosystem being the recurrent and regenerative pattern of youth and maturity. A dynamic balance is achieved through the periodic reestablishment of secondary succession initiated by fire. … It is the unnaturally protected, statically maintained forest, brush,  or grassland climax environment that is nonhomeostatic.” (Henry T. Lewis, “Patterns of Indian Burning in California: Ecology and Ethnohistory”)

“One of the most important recent ecological insights is the critical role of periodic disturbance – fire, flooding, insects, windstorms, to name a few – in maintaining species and habitat diversity. Rather than an anomaly that occasionally disrupts climax communities, disturbance is now viewed as the key recurring factor that keeps a mosaic of habitats in different stages of vegetation development  …. [and] assures the presence of plants and animals that characterize each phase of the change from open land to mature forest.” (Glenn Douglas Dreyer, “Understanding and Managing Vegetation Change”)

“Many wetland ecosystems are not only resilient to periodic disturbances but dependent on them. For example, the floodplains of rivers in the western United States used to support stands of cottonwood trees, which are now declining. The cottonwoods rely on spring flooding for the germination of their seeds. However, once irrigation reservoirs were built to capture the snowmelt, the floods ceased and so did cottonwood generation.” (C. Colston Burrell, “The Natural Water Garden”)

These ideas aren’t new – the quotes above are from the 1970s and 1990s. This is just the first time I’ve grappled with them. If a “stable” system is in fact dangerously unstable, maybe we shouldn’t be striving for a stable, self-perpetuating system but rather for a dynamic system made up of many small parts, in which each part goes through cycles of several hundred years.

Native American tribes seem to have managed this quite well, using fire as the agent of disturbance. But again (see previous post), their success was based on very low population density and a semi-nomadic lifestyle. Trying to apply these ideas to today’s densely populated, settled world is more than a little mind-boggling.

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Changes in the Land

changesinthelandThe brilliant book Changes in the Land, written thirty years ago by the historian William Cronon and said to have launched the field of environmental history (though Cronon modestly demurs), set me thinking about  what we mean by sustainability. Specifically, were Indian practices sustainable?

Cronon describes the land management practices of the New England Indians as of the time the English colonists began to arrive in the early 1600s, as well as the colonists’ practices, and the changes during the colonial period as the Indians dealt with the colonists and the colonists dealt with reality.

The outcome was horrifying. The Indians were largely exterminated, and the once-bountiful region was stripped and depleted of its resources. By the early 1800s, agriculture had moved west and New England was shifting to an industrial economy. Where the Indians had lived off the land for thousands of years, the English made it unproductive in a mere two hundred years. People still lived (and live) there, of course, but only as a part of a complex, global economy that is based on depleting resources in other, once-bountiful regions.

The colonists did not intend these results. The first settlers wanted to improve their own lives a little and not have to work quite so hard as they did in England. Early explorers’ (overstated) reports described the land as fantastically rich. Colonists imagined they could sustain themselves easily and make extra money trading with the Indians for furs and other commodities they could ship back to Europe.

Instead, they killed most of the Indians with germs they didn’t know they carried. (There was no germ theory of disease. Pasteur was not born until the nineteenth century.) They devastated the land because they tragically misunderstood how the Indians had managed it and what effects their own practices would have. In fact, they believed their industrious habits would improve land the Indians had neglected out of sheer laziness. This belief, as Cronon points out, sustained their ideology of conquest.

How the Indians Lived

Saying that the Indians lived off the land is somewhat misleading – it suggests that, as the English believed, the Indians simply feasted at the banquet that nature served up. But New England was not a wilderness. Even the tribes in what is now Maine, who did not practice annual agriculture, managed the land by burning the forest understory in their hunting grounds. (They also managed themselves by moving around in an annual cycle to the places that offered the greatest abundance in each season – something the English, with their fixed habits and household-level property boundaries, could not do.)

Tribes in southern New England, in addition to hunting and gathering, grew the famous Three Sisters – maize, beans, and squash. Contrary to the legend, they did not plant fish to fertilize their crops. They also had no draft animals, which typically fertilized fields in European agriculture. So even with legumes adding nitrogen to the soil, fields were exhausted in eight to ten years. Indian women would simply clear new fields and allow the forest to regrow in the old ones.

Indians throughout the entire area burned vast numbers of trees for warmth, in both winter and summer. Even the colonists were amazed by this – one of them wrote that the Indians used fire the way they used bedclothes. In fact, the Indians assumed that the English had crossed the ocean because they had run out of trees for fuel in their own land (which, as Cronon points out, was not far from the truth).

Sustainable or Not?

In several important senses, Indian practices were sustainable: The tribes had apparently occupied the same land for many years before the English colonists arrived. By late winter, they would be hungry, but outright starvation was rare. They apparently had no historical memories of things having once been better (as they did after the English began despoiling the landscape). Though Indian land management altered the ecology – for example, trees that regrew from their roots after girdling or burning, such as chestnut and oak, were favored, and some areas became deforested altogether – the levels of biomass and biodiversity, the two standards of ecological health, were both high.

Yet Indian practices – though they depended only on living resources, not on fossil resources – were far from energy neutral. If you keep open fires burning year-round, day and night, you take far more energy out of the environment than you can put back in. Exhausting fields every decade works only when you have plenty of land. So what made these practices sustainable is that the Indians kept their population density low (by what mechanism, Cronon is not sure) and didn’t even think of accumulating material goods, which their nomadic habits would have made impractical.

Today, with 7 billion people on the planet and little room to move, sustainability has to meet a higher standard. Humans make up such a large proportion of the ecosystem – and we take so much more than we give – that we can’t simply depend on the land’s ability to heal itself after we move on. We can look to indigenous practices for inspiration, but only for inspiration. We have to be way smarter than anyone had to be in the past.