What is an ecology based landscape? This is the first question I ask students in my Restoration Horticulture course at Oregon State University. It’s always an interesting assessment of how students view the field before delving into the specifics of the subject. So, what is an ecology based landscape, and how is it different than any other kind of landscape?
First, I need to clarify that we’re talking about urban landscapes – residential or commercial – such as a backyard or development site. Some of the impacts typically associated with these sorts of projects include removing most or all of the existing vegetation, affecting soil structure through compaction, chemical alteration, and destruction of the biotic community in soils, changing hydrologic function (water flow), and altering patterns of wind and solar gain. The result is a site that is completely modified and generally unable to recover naturally. Put simply, construction is a severe disturbance to the ecological function of a site.
This is where landscaping comes in. Conventional landscaping practices attempt to mitigate the impacts of development through constructing a replacement plant community based exclusively on the perceived aesthetics of the home owner or neighborhood association (or other organizations overseeing the appearance of a community). The landscape is designed and completed to compliment the architectural character of the structure, and normally includes both hardscape (pavers, sidewalks, patios, etc.) and vegetation. Plants are chosen for morphological characteristics such as size, shape, or flower color, and are frequently planted in arrangements reflecting the vision of the landscape designer.
Most of the plant material planted in these landscapes are cultivars developed for specific qualities such as flower color, plant size, or consistency. The genetic variability inherent in native plants is generally lost during plant breeding or conventional plant production for the landscaping industry. The lack of genetic diversity in plant material is reflected in an overall lack of diversity in soil biota responsible for supporting plants through nutrient cycling and uptake, improvements to soil structure, and plant-water relationships. As a result, most conventional landscapes become dependent on cycles of fertilizing, watering, and pest management. I like to refer to these types of landscapes as “plants on crack.” Plants become highly dependent on chemical inputs (fertilizers) and water, which further suppresses soil biotic communities and results in a landscape that can survive only with active management.
Conversely, ecology based landscaping is a method designed to re-establish the ecologically functional aspect of natural plant associations. Ecology based design emphasizes stimulating growth of soil biotic populations and maximizing above and below-ground biodiversity. Specific methods and materials vary by site, reflecting environmental states or the historic condition of a specific project location. But every design strives to create a fully functional landscape that doesn’t rely on artificial inputs – a landscape that avoids a negative cycle of addiction.
HOW that’s done is a subject for future posts. The first will be dealing with the broad subject of biodiversity; how the term is defined and how the concept can be incorporated in landscape design and construction. Lots of good stuff coming up!