Much has been said about Vermonts changing landscape in recent years. Changing land uses, changing population, and changing social mores are some recurring themes of the times. Yet, some aspects of Vermonts environment change very little.
Geology is the stable underpinning of our landscape. It is the foundation for all plant and animal life and supports a large portion of Vermonts economy. The physical form of the landscape we see today is a result of bedrock type and structure and the surficial materials left behind during the retreat of the ice sheet plus erosive forces at work before, during, and after glaciation. Bedrock is the continuous, solid part of the Earths crust that overlies the mantle (a 2,800-kilometer thick dense layer surrounding the Earths core). Atop the bedrock are surficial materials such as sand, gravel, glacial deposits, and soil.
As the ice retreated 10 millennia ago, it left behind surficial materials on the scraped bedrock in the form of till or stratified drift (gravel, sand, silt, and clay). Formation of most soils in Vermont actually began about 13,500 to 10,500 years ago on the surficial materials that fill Vermonts valleys and cover our uplands. These physical features have a profound influence on the flow of water and the biological environment.
Geological research helps Vermonters locate earth materials and drinking water supplies. Providing easy access to current geological information is critical to the continued success of managing Vermonts natural resources and directing growth in a sound manner. This will help to manage our resources and balance the impact of human activity with protection of the environment.
Another measure of the landscape is its biophysical regions. These are areas that share similar soil, climate, and landscape features and tend to produce similar plant communities at given elevations. In recent years, the Agency has worked with the U.S. Forest Service, the University of Vermont, and a number of other interested parties to identify Vermonts biophysical regions for the purpose of making better decisions in managing forests. If we know the physical characteristics (bedrock, soils) of a region, its biological features (vegetation, animals), and its climate, we can better understand what kinds of actions can be taken to work in harmony with the environment. Ultimately, this will lead to a more productive and sustainable environment. A partnership of private and public organizations informally adopted the biophysical regions map in March of 1998 (Figure 1) .
Determining what type of timber to grow on a specific property provides a good example of putting this information to work. If a landowner tries to grow quality northern hardwood trees on a spruce-fir site, disappointment is the likely result. The hardwood will generally be of poorer quality, and the much-needed balance of softwoods will be missing. These conditions will reduce biodiversity, eliminate important wildlife habitat, and reduce the available softwood lumber supply.
For the next, more-detailed, level of mapping, the Agency of Natural Resources has chosen to use a natural communities classification because its simple enough for general use and has been tested and used throughout New England. (Natural communities are defined as an assemblage of plants and animals, recurring across the landscape under similar environmental conditions, where natural processes prevail. A natural community could be less than an acre to thousands of acres in size.) The Nature Conservancy, in concert with other groups, is developing a field guide to help identify these communities.
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