A broad and growing body of scientific literature is documenting the basic ecological services, and associated economic values, provided by urban and rural trees, woodlands and forests. It is becoming increasingly clearer with each passing day that these services are critical to the health and well-being of our expanding population.
In light of these findings, the conservation and restoration of urban and rural forests must now be seen as a fundamental goal of any viable land use planning process. But, land use planning that seeks to sustain forests and trees will need to be based upon a contemporary understanding of the ecological assumptions that underpin our understanding about how forests function.
The prevailing scientific understanding of forests in the 20th century suggested that they were self regulating, and when disturbed moved in a predictable manner toward a state of equilibrium. It was also assumed that humans were not components of forest ecosystems. These assumptions are part of a mechanistic view of the universe that can still be found in textbooks and popular nature-based literature.
The ‘balance of nature’ metaphor is often associated with these assumptions and is still heard in public debates concerning conservation. Missing from this traditional perspective is the concept of ecosystem, which recognizes the reciprocal nature of organisms and their biological and physical environment.
Advances in our ecological understanding of forests has provided us with quite a different perspective. We now recognize that forests and woodlands ecosystems are open and often dependent upon some level of disturbance. They are not self regulating and have probabilistic dynamics with no or multiple equilibria. Humans, their direct and indirect effects, are now recognized as integral components of forest ecosystems. This contemporary scientific understanding is the basis for the holistic approach to forest conservation embodied in ecosystem management.
An ecosystem approach to forest conservation requires consideration of ecological processes such as the movement and interaction of organisms, cycling of nutrients, transformation energy and the reorganization of forest communities following disturbance. Landscape context must be made part of any conservation scheme, since forest ecosystems are open and influenced by their surroundings and spatial connections. No longer can forests, woodlands or urban parks be seen as natural area islands capable of sustaining themselves.
The State of Maryland provides an example of a land use management program which has had some demonstrated successes in taking an ecosystem approach. County comprehensive land use plans are required to lay out projected land use types, patterns and intensities in a manner that seeks to protect the ecological service values of the forest landscape. Maryland’s Forest Conservation Act and Critical Areas Law require the incorporation of targeted forest protection and restoration. Wildlife conservation and the siting of appropriate forms and densities of development based upon landscape context are considered key elements of any land use change decisions.
Maryland’s Open Space Program compliments the efforts of local land use planning. It incorporates the use of a real estate transfer tax to support the purchase of public lands as part of a planned state wide greenway system. The greenway system supports recreation, plant and animal habitat conservation and protection surface water quality. Together these programs address the need to consider the ecological values of existing natural systems (forests), streams and wetlands in making land use decisions within a holistic watershed context.
The history of forest conservation and management in the United States can be seen as a continuous dialogue between societal values and our scientific understanding of forest ecosystems. While changes are afoot, the societal values being expressed through many land use management programs today do not match our ecological understanding of the dynamic nature of forest ecosystems. As a result, we continue to make mistakes that lead to the loss of the forest land base and its intrinsic and societal values.
What is required is the adoption of a conservation ethic that provides analysis and protection of the ecological values of forest land before the preliminary site design phase of the land use change. To accomplish this, planning departments will need to have qualified staff, knowledgeable in ecological processes and land management.
Our contemporary society needs to move beyond the old paradigm of the ‘balance of nature’ and embrace the uncertain reality of natural forest systems that are dynamic and greatly affected by the pattern and intensity of human activity in and around them.