Home Landscapes for Environmental Sensitivity
American residential landscapes of the last 50 years typically use evergreen shrubs planted against the foundation of the house surrounded by manicured lawn. These landscapes are often environmentally insensitive in a variety of different ways. They generally require more maintenance, chemical fertilizers and pesticides, and supplemental irrigation to achieve the desired aesthetic effect. These practices can contribute to a number of current environmental problems, from air and water pollution to consumption of fossil fuels.
An approach to landscape design that helps to avoid these environmental problems is commonly called "natural landscaping". Natural landscaping follows principles based upon local climate and ecology, and utilizes plant and other materials which are adapted to the local conditions. By utilizing local plant species and arranging them in ways which imitate local ecological communities, natural landscapes usually require less maintenance and are substantially more environmentally sensitive.
Starting an environmentally sensitive landscape
To create a natural landscape, one must first gain an understanding of the type of community which might naturally occur on your site. A good place to start is with an inventory of the important site characteristics and features. These might include: climate, soils, drainage patterns and existing vegetation (if any). Each region can generally support a variety of ecological communities, and by analyzing the specific qualities of your site, you can reasonably select the appropriate community(s) for your site.
Each site has its own "micro" climate. These are conditions created by sun, wind, and moisture. Examples include: low spots which may collect water and are prone to frosts or even the differences from the sunny to shady side of a house or other structure. Plants that are not well adapted to the localized micro-climatic conditions will only survive with added maintenance.
Soils are a product of local geology and climate. Soil is a combination of minerals, air, water and organic matter. Variations in the quantities of these four components determine the types of plants which are likely to adapt to your site. In addition, soil chemistry (measured by pH, or degree of acidity) influences nutrient availability-different plant species are naturally adapted to soils of various pH levels.
Hydrology concerns the presence and movement of water above and below the surface of your site. Hydrologic conditions, i.e. precipitation runoff and soil moisture, are influenced by topography, soil type, and micro climate.
While areas of a site that stay wet for more than a day or two present a planting challenge to the traditional design styles, these conditions offer a unique opportunity for natural landscapes. Streams, ponds and other surface water features present additional opportunities for plantings naturally adapted to these habitats.
All plants are adapted to certain levels of sunlight, and can be categorized by their degree of light dependence. In Central New York landscapes, characterized by woodland ecological communities, this dependence generally corresponds to the location a plant typically occupies in the vertical structure of the forest. Generally speaking the tallest species (canopy trees) require the most sunlight. Shorter species growing in the shade and protection of the taller species (understory trees and shrubs) require less light while most ground layer species grow in somewhat restricted light levels. Meadow and aquatic species are not commonly categorized in this manner, their arrangement depends more on seasonal variations.
An exception is the spring forest wildflower. They require high light levels even though they grow on the woodland floor. They have evolved to take advantage of the sunlight available before the canopy leafs out and shades them.
Regional Plant Communities
Plant communities are described as many, often interdependent, species of plants which grow under similar environmental conditions, i.e., soils, climate, hydrology, etc. Unless there are abrupt changes in environmental conditions, communities are seldom distinct and blend together to some degree. In Central New York, there are three major plant community types: Woodland, Meadow and Aquatic.
Central New York was once covered by woodlands composed primarily of Beech-Maple and Oak-Hickory communities. Beech-Maple woodlands occupy areas of rich, moist soils on slopes and in valleys. Oak-Hickory woodlands, on the other hand, are found where the soils are drier, on upper slopes and upland areas.
Woodlands have an interior (drawing at left) and an edge (drawing below). Woodland interiors are dominated by the canopy layer, with sparse understory and shade tolerant ground layer species. Conversely, woodland edge plants are densely populated in each layer, where they are more exposed to sun and wind.
Meadow plants have evolved where regular disturbances occur or various other factors (i.e., soils, climate, etc.) do not allow woodland growth. In Central New York significant disturbances that prevent trees and shrubs from growing are human intervention, fire, or animal grazing.
Meadows have a diverse and seasonally variable pattern of grasses and forbs (broadleaf flowering species) randomly arranged in a single ground layer. Meadows offer year-round interest through a succession of growing season blooms, followed by colorful fall and winter foliage.
Aquatic communities, whether forested (swamp) or marshy (grasses), have adapted to constant water fluctuations and wide variations in chemical and nutrient compositions. Aquatic species which adapt to these variations can be used in the natural landscape as an alternative to filling or draining "problem" wet areas.
Following the determination of an appropriate community for your site, a natural landscape will take time to install and establish. Two methods are typically considered. One method promotes incremental establishment, adding plants as conditions become appropriate, the second advocates complete installation at one time. These methods differ in both cost and philosophy. Gardens started all at once require significant numbers of mature plants, and a very clear understanding of the likely interaction between species. Often the more vigorous plants out-compete the less vigorous, leaving only the most aggressive. Consequently, this method has variable results. Ideally, the second method is used, and the site is planted in stages, adding plants as site conditions become appropriate for each species' growth.
In each case, care should be taken in the acquisition of plant material. Plants should
come from a reputable nursery that propagates local plant species rather than digging
them from the wild. As a possible alternative to purchasing from nurseries, plants
can be collected from sites similar to your own which are threatened by development
of destruction. In each case, the property owner should be consulted for permission.
A natural landscape takes time to develop but the rewards are many. Along with the potential for decreased maintenance and increased environmental sensitivity, natural landscapes can provide habitat and food for many species of wildlife.
For more information on starting a natural landscape, refer to the following books:
Livable Landscape Design, Marvin Adleman and John Collins, Cornell Extension Publication.
The Natural Habitat Garden and The Natural Shade Garden, Ken Druse, Clarkson Potter Publishers, New York.
Naturalized Landscapes, John Diekelmann and Robert Schuster, McGraw-Hill, New York.
Prepared by Alexandra Morgan and Scott Shannon, Department of Landscape Architecture, and Norman Richards, Department of Forest and Natural Resources Management, SUNY-ESF.