Interdependency of Land, Climate, and Tree Cover
by Lara on September 16, 2007Cronon describes how people change the land and affect local climate. This might be termed ethno-ecological history.
The author is a Rhodes scholar who earned a doctorate in philosophy from Oxford and taught history of the American West and American urban history at Yale. His clear interdisciplinary approach synthesizes ethnology, ecology, plant and animal husbandry, and climatology.
While the American Indian worked with nature in surprisingly sophisticated ways to increase the productivity of the land, the European man-against-nature approach resulted in a dependence on relatively few plants and animals for a survival level economy.
The book begins with material from Henry David Thoreau’s Walden, in which he records the changes since the 1633 book “New England’s Prospect” talked of a wealth of wild berries, varied forests, profusion of fish and wild game, both mammal and fowl. Thoreau wondered at the disappearance of swans, heath cocks, and turkeys in the intervening two hundred years. Bass had once been caught in batches of two or three thousand at a time.
The native Americans were surprisingly sophisticated in their land management. Not only did they stave off exhaustion of the soil by planting beans with the corn, but they also set fires to the forest twice a year. These fires burned out quickly, cleared out the underbrush, produced a wealth of berry crops as well as ideal fodder for deer, made the forest passable for game and hunter alike, and also produced grasses for grazing.
It also increased the rate at which nutrients were recycled into the soil, so that the grasses, shrubs, and non-woody plants tended to grow more quickly and productively. This is what produced bumper crops of strawberries, blackberries, raspberries and other berries. The thinning of the forest canopy by burning eliminated smaller trees and allowed more light to reach the forest floor. Soil became warmer and drier, and favored oaks above all other species of tree. Trees that were able to resprout from stumps won out over those that would have choked the forest into a scrubby tangle of hemlock, beech, juniper and pine.
The colonist by contrast used fire, not to control underbrush, but to burn out the forest itself for cropland. “Trees that required and maintained moist forest conditions, such as hickories, maples, ashes, and beeches, generally produced a rich black humus beneath their fallen leaves, and settlers interpreted them as indicators of prime agricultural land. Oaks and chestnuts, with their denser undergrowth and more frequent ground fires, had thinner soils which required more work before they would produce favorable European crops.” They avoided acidic or sandy soils or places that thorny bushes grew.
What the colonist did not understand and what even modern farmers did not, was that the trees produced the soil as much as the soil produced the trees. The forest is an effective and complicated machine for regulating evaporation and recycling nutrients. Forest soil was moist because the trees kept it there. When the parent forests were removed, the soils were often exhausted within a generation.
Much more research than I can summarize here is in this modest volume.
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