Tuesday, May 29, 2012

Doug Tallamy on "Biological Corridors: Networks for Life"

The first time I heard entomologist Doug Tallamy speak was at a Master Gardener training day. It was, I think, six years ago, and it was a real “aha” moment for me. I hadn’t had a yard of my own for that long, but I was already an enthusiastic grower of native plants.  I understood some of the benefits of growing plants native to the local area: they were less likely to require a lot of maintenance once established, less likely to become invasive, helped establish a sense of place, helped support wildlife, etc. What hadn’t occurred to me, or to a lot of other people, I think, was the critical importance of native plants as a food source for native insects.

In that talk, and in his subsequently published book Bringing Nature Home:How Native Plants Sustain Wildlife in Our Gardens, Tallamy explained that most native insects have evolved to feed on only a small number of native plants. Without these specific plants, the insects can't survive. This in turn impacts the species that depend on insects for food; for example, the vast majority of migratory birds raise their young on insects.

Other animals also rely on insects for some part of their diet. Without native insects, a huge food source disappears; non-native plants are far less productive of insect biomass. These insects, in other words, are a critical part of the food webs on which life depends. The lawns and non-native plants of suburban lawns and gardens do not provide food for native insects – they are basically food deserts. Tallamy thus built a quite compelling case for homeowners and gardeners to incorporate native plants into their yards and as much as possible.

Last week I heard Tallamy speak again at a Master Gardener training day. This time his focus was broader: on the need for biological corridors, which, he said, are not just corridors for animals to pass through, but habitats in themselves. At this point, he maintained, biodiversity cannot be sustained by parks and preserves alone. We must restore land between existing landscape fragments, everywhere. Obvious places to do so are along roadways and power lines. Roadways can be planted with trees; power lines, as they pass through the landscape, are usually mowed and can be good edge habitat. Beyond that, if we turned half of all existing lawn into habitat we would be creating a "Homegrown National Park" of over 20 million acres, which would go a long way toward protecting future biodiversity.

We gardeners are lucky, I think. We can hear and understand the message about loss of biodiversity, which is pretty dire. At the same time, we’re in a position to contribute to a solution, simply by doing something we love, gardening, with  nature instead of in opposition to her. “The landscape challenge of our time,” says Douglas Tallamy, “is, more plants!” That’s something to make any true gardener’s heart beat faster!