Saturday, December 13, 2008

Landscape - Horticultural Ecosystems IV

This post is a continuation of the series on understanding horticultural ecosystems as a part of sustainable landscaping practices. Slides are from a presentation that I give on the subject.

After a site is disturbed, a new ecosystem must be established. The function of this new horticultural ecosystem is dependent upon the choices you make as a landscaper. It is important to consider plant interactions with the specific environment. Planning should take into consideration ecological factors, what is the desired ecosystem, what do you need to take into account in the site environment to arrive at the desired horticultural ecosystem, expected interactions in the new landscape, how the landscape will be used, and of course aesthetics. Consider more naturalized areas if possible and use native plants as much as possible.

This landscape has achieved a balance between having areas that function for the needs of the homeowner (a lawn area for children to play) and landscaped areas that build a sustainable horticultural ecosystem. One negative would be that not enough native plants are used.

One way to view the initial stage of landscaping is as a healing process. You need to understand the soil changes that need to take place to quickly develop the new horticultural ecosystem and add amendments to help that process along. As plants root into the new landscape, a new ecological community starts to develop.

Over time, as the landscape matures, changes take place and the ecosystem evolves. Understanding this process is key to landscape maintenance needs.

Landscaping is in essence a controlled succession of species. Young landscapes will favor certain species and more mature landscapes will favor other species. Trying to force species to grow in this succession out of their natural adaptation will result in failures or excessive maintenance needs.

In your landscape design, one of the most important set of decisions that you have in establishing a new horticultural ecosystem is species selection. Once the selections you make are installed, natural processes will act upon those species. As the horticultural ecosystem evolves, other selections are made naturally including plant invaders (weeds, invasive plants), animal selections (both pests and beneficial animals, for example you can have insect pests and beneficial insects), and microbial selections (again both beneficial such as mycorrhizal associations with roots and detrimental such as plant pathogens).

Your species selection is very critical for the new horticultural ecosystem. Diversity should be sought. Think of short term and long term effects of your selections. Native species offer significant advantages in adaptability and in support of desired wildlife (habitat). Poor selection can result in problems such as invasive plants and pest buildup.

I will have more on this subject in future posts.

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

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