By Joan Herskowitz. Article reprinted in Let’s Talk Plants! January 2023, from "The Lagoon Flyer" newsletter by permission of the Buena Vista Audubon Society.
A Homegrown National Park
How do we address the ongoing decline of wildlife populations and biodiversity?
Doug Tallamy, a professor and researcher in the Department of Entomology and Wildlife Ecology at the University of Delaware, believes that it’s not enough to depend on our national and state parks and nature preserves to sustain wildlife into the future and prevent species extinctions.
His message is that we need to take environmental action into our own hands by growing native plants where we live and work.
Whether you have a small or large property in a town, city, or suburb, he believes you can be part of the solution to increase biodiversity by expanding native habitat corridors throughout your region.
You may have heard this before; but his book, Nature’s Best Hope: A new approach to conservation that starts in your yard (Timber Press, 2019) is an eye-opener to the specialized relationships between insects, plants, and animals and how important they are to local ecosystem functioning.
Tallamy and his graduate students study insect feeding patterns on plants and trees, showing that native plants support much larger and more diverse populations of insects. He attributes this to the fact that native species have a common evolutionary history. When native plants disappear, the insects disappear, impoverishing the food source for birds and other animals. Their research has also shown that a few genera of native plants, or keystone genera, form the backbone of local ecosystems, particularly in terms of producing the food that fuels insects in most of the country. These include the native woody producers (oaks, the superstars; cherries; willows; birches; cottonwoods; elms) and the native herbaceous plants (goldenrods, asters, sunflowers). They discovered that these plants enhance populations of caterpillars, the nutritious mainstay of most bird diets, as well as populations of butterflies, sawflies, and bees - insects that are responsible for most of the pollination required by plants.
If native landscaping were established in yards, millions of acres across the country could be converted into habitat. However, it’s not all or nothing.
So, if only part of a property were converted, that would still be a large area. This scheme would create the country’s largest park system at our homes, and therefore Tallamy calls it a Homegrown National Park. It’s an intriguing idea and Tallamy’s books are full of fascinating stories to gain your interest. There’s something to learn in all of Tallamy’s books. But another that I especially recommend is The Nature of Oaks (Timber Press, 2021) - his call to understand, protect, and increase the population of oak trees, which he considers the most significant tree for sustaining wildlife.
Because the Tallamy recommendations refer to the country as a whole, the author recommends The National Wildlife Federation website to find out keystone plant species in San Diego. There is a list there of keystone native plants for our ecoregion (Ecoregion 11 - Mediterranean California) and the numbers of insect species that use each as a food source.