Planting native species promotes biodiversity, says speaker

Incorporating native plants into landscape design can play an important role in promoting biodiversity, according to ecologist Doug Tallamy.

“We need to change our landscaping paradigms,” said Tallamy, a professor of entomology and wildlife ecology at the University of Delaware. “Animal diversity needs native plants.”

Tallamy was the keynote speaker at a day-long symposium on invasive plants held at Rome Ballroom Oct. 1. The event was organized by the Connecticut Invasive Plant Working Group, a coalition of concerned individuals, organizations, and agencies. The group is co-chaired by UConn’s Donna Ellis of the Department of Plant Science and Les Mehrhoff of the Department of Ecology and Evolutionary Biology.

Tallamy said that despite extensive degradation of the environment by humans, individuals can have a positive impact on biodiversity in their own backyards by planting native species.

Biodiversity is needed for a healthy ecosystem, he said, and animal diversity comes from plants.

Tallamy said the destruction of nature by human beings “has happened so many times in so many places, we’re losing the species we share the planet with. … We don’t make the mental connection between how important other living things are and our own well being.”

Plants – because they produce food for other species and their structures offer a place for other species to live – determine the number of species that can live in a space indefinitely without degrading resources. This is known as carrying capacity.

Not all ecosystems have the same carrying capacity, he said. A deciduous forest, for example, has a higher carrying capacity than a lawn.

The carrying capacity of the United States has been depleted, he said. Suburbs and cities make up 54 percent of the country, and these support very little biodiversity.

“The carrying capacity of suburbia is extraordinarily low,” said Tallamy, “because it was not designed for biodiversity, it was designed for convenience.”

Not all plants support wildlife equally, he said. Plants that evolved elsewhere don’t support wildlife as well as native plants.

“In a typical suburban landscape, none of the plants are native,” he said.

Tallamy described an experiment he carried out in his own backyard, comparing the biomass of caterpillars on native plants and on alien species. He found 35 percent more on native than on alien species. “That’s 35 times more bird food,” he said.

On average, an alien plant supported only four species, compared with 71 species on a native plant.