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Ecology for Gardeners: Introduction
Ecology: The science of the relationships among living organisms and between organisms and their environments.
Ecosystem: A functioning unit of nature that combines biological communities and the environments with which they interact. Ecosystems vary greatly in size and characteristics.
The science of ecology had been developing for over a century, yet most people never heard the word until the 1960s and the publication of Rachel Carson's book, Silent Spring, which documented how chemical pesticides were spreading insidiously through the food chain and threatening the survival of many bird species. The book brought into sharp focus the ease with which the natural balance of plants, animals, and the environment that comprise life as we know it on this planet can be tipped. From the oil crises of the 1970s to the nuclear fallout from the Chernobyl reactor in the 1980s to the more recent evidence of ozone depletion and climate change on a global scale, we continue to be reminded of the need to protect the biosphere.
Gardeners are mainly concerned with plants, specifically the ones we grow in our gardens. But our gardens, as Rachel Carson showed us, are inextricably linked with the larger landscape. As cities and suburbs spread, gardens and other human-influenced environments predominate. It is our task as tenders of the Earth to assure that the role our gardens play is a positive one. This requires an understanding of ecological relationships.
The first step in understanding ecological relationships in the garden is understanding those in plant communities in the wild. Have you ever wondered why oaks grow in some woods and not others? Why the East is covered largely with deciduous trees, while in the West conifers dominate? For decades, scientists have been studying vegetation associations, the distinctive mixes of species that predominate in different areas of different regions. Over the past century or so, ecologists have learned that such natural systems are defined by two major kinds of order: structural and functional. A terrestrial ecosystem's structure, or form, depends primarily on its vegetation: the structure of a grassland is very different from that of a forest, for example, because of the form of the predominant plant life. By the same token, the functions of these two plant communities - how they respond to fire, wind damage, and other types of disturbance, how they use and recycle water, nutrients, organic matter, and so on - also differ because the physical environment, the soils, climate, and other conditions that give rise to them, are different.
What follows is a basic introduction to the structure and function of the major vegetation associations of North America, and how gardeners in these various regions can use them as models for transforming the garden landscapes that sustain us, without destroying the creatures and natural communities with whom we share the Earth.