Sunday, December 14, 2008

Landscape - Horticultural Ecosystems V

I often recommend that the landscape should be viewed as a horticultural ecosystem where the landscaper's influence is critical and the decisions they make can affect the balance. By understanding the horticultural ecosystem, landscapers can often make better decisions. The goal is to create a sustainable landscape system. This is the fifth in a series of slides on the subject from a presentation I give.

Diversity should be a major goal of any landscape. The diversity in a horticultural ecosystem is selected by you as the landscaper or landscape designer. Large expanses of lawn are not diverse systems. Neither are single species screens or windbreaks. Most of our landscapes have limited diversity with only a handful of mainly non-native species. This can lead to many problems such as increased pest problems, reduced habitat for desired wildlife such as birds, high maintenance requirements, and reduced longevity of plantings.

A common suburban landscape. Diversity is limited to a monoculture of grasses, a few shade trees, and a few foundation plants.

In horticultural ecosystems with limited plant diversity, the diversity of other organisms is also limited from soil microbes to desired wildlife. Food sources for native animals are limited thus limiting their numbers in communities that have low diversity of plants and many non-native plants. Pests are often more of a problem and reduced plant vigor often results. There is a reduction in the benefits from plant synergism. Landscapes can also be very monotonous and of low aesthetic value in these low diversity systems.

Create more horticultural ecosystem diversity by selecting a wide range of plants from many different plant families and using a majority of native plants. You can add diversity to any landscape by replacing existing plants with different species and by converting parts of lawn areas to landscaped areas. When adding plants or designing systems, consider how plants are placed and what effects they will have on each other. Design for complimentary effects. Alter soils to favor the species that you install. Eliminate those plants that have high maintenance requirements from a pest management perspective or that are pest prone.

I will continue these thoughts in additional posts.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County.

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