Monthly Archives: April 2017

Death by Urban Landscaping: How popular landscape plants are destroying local forests

by Beverley Rivera.

As the weather warms, Northern Virginia appears to come alive almost overnight, trees leaf out and unique wildflowers blossom beneath the awakening canopy; but this greening of everything around us actually belies a chilling outlook: much of the striking new foliage is not supposed to be here. Plants that are not native to America are rapidly outcompeting local forest growth for resources: growing space, sunlight, water. In many areas, not only are the invasive plants winning the battle for these resources, they are annihilating the local competition.

Chinese wisteria (Wisteria sinensis) can displace native vegetation and kill trees and shrubs by girdling them. Photo by Matt jones/NatureServe/cc.

Chinese wisteria (Wisteria sinensis) can displace native vegetation and kill trees and shrubs by girdling them. Photo by Matt Jones/NatureServe/cc.

And it’s a problem without a solution because many of the plants that are steadily destroying Virginia’s forests are spreading from people’s gardens and from landscaping at shopping centers and businesses. There are breathtaking areas in Northern Virginia where invasive vines so thick that they require a saw to hack through are suffocating native trees that withstood Civil War battles. Homeowners and landscapers plant these vines in urban settings, the seeds get into the forest via birds, and the non-native plants quickly take over, entangling, suffocating, stunting and displacing everything natural. Invasives such as Chinese wisteria send out vast networks of thick vines that spread above and beneath the ground, quickly engulfing massive areas of natural forest.

Another frightening prospect is that in the normal cycle of things, young trees which are just now getting established would, hundreds of years from now, replace the massive canopy trees as they end their life cycles. If left untainted, the forest rejuvenates itself as it has for thousands of years. But with invasive plants taking over, the young growth that is destined to be our forest of the future is being entangled, smothered and displaced by invasive plants. Adding to the problem is overbrowsing by deer. Deer won’t eat many of the invasive plants, and the natural predators that once kept deer numbers in check are no longer roaming the east.

In fact, the Fairfax County Park Authority’s Invasive ID and Control booklet looks more like a guide to urban landscaping in Northern Virginia.

Equally destructive to our new forest growth are Japanese honeysuckle and English ivy. But these plants are ubiquitous in local landscaping, meaning that even if an army of volunteers managed to remove all the invasives from an area, the seeds from urban landscaping would quickly reinfest the forest. Invasive butterfly bush is another staple in Northern Virginian landscaping, as are Japanese barberry, Pachysandra, Miscanthus, Bradford pear, privet, Norway maple, burning bush; the lists of plants that become invasive once they leave the suburban landscape is ongoing. In fact, the Fairfax County Park Authority’s Invasive ID and Control booklet looks more like a guide to urban landscaping in Northern Virginia.

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English ivy before and after: for sale at a local garden center and its escape into the wild.

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