Gardening Nature’s Way: Native plant! The ecology of the peri-urban landscape | The Harvard Press | Features | Feature Articles

Imagine being mysteriously transported, without your smartphone, to an undisclosed suburban yard somewhere in the United States, like Salt Lake City, Boston, or Phoenix, and having to search for clues as to where you are. What could you do to find your bearings?

You may be looking for the presence of native plants such as trees and shrubs. You can also check the structure and combination of plants, terrain, rock formations or even soil. For example, if you saw white pines and red oaks growing together at low elevations, a forest in Massachusetts would come to mind, but the same combination would be much rarer in Virginia and unlikely to occur at low elevations.

However, chances are that your instincts about what a regional ecosystem should look like wouldn’t help you much in this scenario: you’re probably looking at grass (perhaps Kentucky bluegrass), plants with non-native flowers, a few large specimen trees, a walkway, containers full of annuals and other lawn accessories. you’ll either have to look in the fringe areas of the yard or scout the wider neighborhood for undeveloped plots.

This thought experiment illustrates a fascinating question that a group of ecologists and data scientists have been working on: how strange is it that urban and suburban residential land use is so similar across the United States – and what does it do to our environment from a scientific point of view? measurable point of view?

Over the past two decades, a growing body of research on this topic, with results published in journals related to ecology, landscape, and environmental issues, breaks these questions down into measurable components. Ecologists Peter Groffman and Christopher Neill, in several studies, have calculated that homeowners dump the same amounts of fertilizer and water on their yards nationwide despite vastly different soil types and annual rainfall patterns. Homeowners’ tastes for ornamental plants and the uniformity of species available in the garden section of big box stores nationwide result in the same types of plants – often from a few plant families such as the Fabaceae (the family legumes), Rosaceae (the rose family), and Solanaceae (the nightshade family) – filling borders and containers from Arizona to Massachusetts.

Besides the flowers and shrubs that people like to grow in their gardens, there are other similarities: people create very uniform structures and growing conditions, which in turn promote uniformity of functional characteristics. Homeowners often cut back the natural layers of the landscape, isolate a few large specimen trees, and create a lawn that looks like a displaced savannah.

A study of suburban yards in Minneapolis-Saint Paul by Sonja Knapp published in Ecology in 2012 highlights the unique changes brought about by typical landscaping and maintenance practices in terms of ecological structure, function and composition: higher relative humidity, higher disturbance rates, and higher specific leaf area provided the configuration of an environment that functioned quite differently from the local natural area used as a control in the experiment. “Specific leaf area” measures the leaf area produced by the plant in relation to its dry mass. Basically, it tells you how a plant allocates its resources as it grows, which in turn affects how it recycles carbon and water, and how it behaves. in the plant cover.

Specific leaf area is an interesting metric to look at in suburban lawns because it shows that a lot is happening when we remove and thin out layers of our landscape, including effects on leaf size and shape. , nutrient cycling and reproductive patterns of species. . Consider what it entails to clear the “brush” along the edges of the yard – a task that typically involves removing much of the understory shrub and tree layers to create a cleaner look or thinner in the wooded margins of the yard, but which will also affect the growth patterns of the remaining flora and create a ripe setup for invasive species.

Changes in courtship structure, according to Knapp’s 2012 study, favor species that can reproduce and spread quickly. Annuals and self-pollinated species survive and spread much faster than perennials and pollinator-dependent species. This means that the petri dish of the urban-suburban court is ready to go forward and multiply beyond the palisade. It’s no coincidence that many invasive species come from nursery stock that people once planted in their backyards.

From an ecological gardening perspective, it would therefore make sense not only to plant native plants, but also to think about how these plants might occur naturally. Creating a managed landscape that is more like the less disturbed areas of the neighborhood will help our natural environments, as well as anyone stuck in a random thought experiment trying to find their location without GPS.

For a discussion of how to use layers in landscaping, see “The Living Landscape: Designing for Beauty and Biodiversity in the Home Garden” by Rick Darke and Doug Tallamy, 2014.


Catherine Warner is an enthusiastic home gardener, freelance writer, and educational consultant who lives at Harvard with her family and their beloved dog Moe.

White pine, eastern red cedar and red oak growing at low elevations are a clue that you are viewing a New England landscape. (Photo by Lisa Aciukewicz)

Terri S. Tomasini