More Than Just a Pretty Place: Landscaping to Provide Ecosystem Services
By Brian Williams, Forest Restoration Manager, Trees Atlanta
Atlanta is in a period of rapid redevelopment and infill, and as the value of property increases, so do the performance demands we need to put on that property. As we densify, we lose the forest fragments, edge trees, undeveloped lots, and other forgotten spaces that previously served valuable (if unnoticed) ecosystem services. These services include visible benefits like stormwater management, erosion control, and wildlife habitat, and invisible ones like air quality improvement, temperature modulation (i.e. shade), and improved overall health and well-being. As we replace the undeveloped with the developed, or even as you look at your decades-old yard landscape, there is room to provide ecosystem services within the fabric of our residential and commercial landscape.
Traditional landscaping practices often limit the ability to provide the majority of ecosystem services. The required care of the turfgrass lawn is such that it requires a significant amount of annual inputs (fertilizer, pesticide, regular mowing, supplemental irrigation) for very little gain. A tree’s root zone absorbs more stormwater per square foot, and its canopy provides many vertical layers of wildlife habitat along with a greater leaf mass for air purification than a lawn occupying the same square footage.
Another landscaping practice that needs reconsidering is our penchant for evergreens. There is a pronounced bias against deciduous shrubs that go bare in the winter (seen as “unsightly”), and a strong desire to plant walls of evergreen hedges (such as privet) or trees (such as Leyland cypress or Chinese holly) to create privacy. As there are very few truly native evergreen shrubs, this invariably leads us into planting introduced, exotic shrubs, many of which prove problematic. Most don’t provide food for the community of native insects that are the foundation of the urban wildlife food web, and some are downright toxic to animals. Nandina berries, as an example, release cyanide compounds when consumed and kill the birds that eat them.
An increasing trend in our urban landscape is yard spraying for mosquito control, and this is an issue charged on both sides. The mosquito plaguing us most in Atlanta is the introduced tiger mosquito, which lives and breeds near human habitation. Yard debris, clogged gutters, and dense beds of foliage near ground level (such as English ivy) can hold enough standing water for this mosquito to reproduce. Commercial mosquito sprayers will target zones of foliage in your yard where mosquitoes congregate and spray them with barrier pesticides. This will kill adult mosquitoes that come into your yard and land on sprayed leaf surfaces; however, it doesn’t address the areas of standing water where mosquitos are reproducing, nor does it address the mosquitos that are born in other yards on your street. Without creating a cooperative mosquito district, in which different types of mosquito control (not just barrier spraying) are practiced in tandem with your neighbors, spraying your yard in isolation is a temporary solution. And as a temporary solution, it will have to be repeated, which builds up pesticide resistance in mosquitoes and causes cumulative, collateral harm to non-target insects that also land on treated leaf surfaces (including fireflies).
There is room to nurture a beautiful landscape while not slowly destroying your local ecosystem. Great strides are being made in the propagation and marketing of native plants for your landscape, plants which support our local food webs and look good doing it—purple coneflower, blueberries, and native deciduous azaleas are three prime examples. Don’t neglect your trees–trees are the pinnacle of plant evolution in their complexity and provide more ecosystem services than any other class of plants. Protect the trees you have, respect their root zones, ameliorate their decline (good pruning and fertilization can help extend the life of an over-mature tree), and plant for future generations of trees (and people). Don’t view your landscape in isolation—what you plant and how you maintain your yard affects your immediate neighbors, your entire neighborhood, and everyone else downhill from you in your particular watershed. Then we can create a healthy place and ecosystem for people and the other living things we both need and love.