Over the years, I have heard about a professor at the University of Delaware named Doug Tallamy and his thesis that we need to use more native plants in our landscapes. Two days ago, while attending the Ohio Nursery and Landscape Association Short Courses, I had the opportunity to actually hear him speak.
We all realize how development has destroyed many of our ecosystems. Although it will not be easy to counter this destruction, Tallamy believes that we can act individually to achieve positive affects.
First, we need to be aware that many insects and birds rely on native plants, particularly woody plants but also perennials and grasses, for food and shelter and that the extinction of each species will lead to the extinction of others elsewhere in the food chain. We can nurture ecosystems by planting native trees that host a multiplicity of caterpillars. I was astounded to learn that the majority of food that birds bring to their offspring in the nest is composed of caterpillars. His photos of a variety of caterpillars captured their amazing diversity and beauty.
Second, I learned that the roots of trees form a matrix that helps keep them from being uprooted by high winds and heavy snows unlike the roots of specimen trees that are much more susceptible to such conditions. Therefore, we need to change our design approach to planting trees. Let’s plant groves rather than single specimens in sites that are large enough.
I’ve written in the past about the size of lawns which Tallamy calls default landscaping. He also pointed out that turf does not supply habitat or food. If we diminish the size of our lawns, keeping enough for play and as contrast to beds, we can build biological corridors to help counter the fragmentation of habitat and the destruction of ecological function.
Tallamy believes that native plants are more productive, e.g they support food webs better, than non-native plants, because 90% of the insects that drive those food webs are only adapted to local native plants. What we don’t know yet is whether cultivars of native plants provide the same function. This research is now underway but it will be at least a few more years before we know the answers. Interestingly, Tallamy had statistics that show not all natives are productive in the food web.
I have never been and will never be a purist, planting both natives and non-invasive “exotics” in my gardens but I will start planting more natives in my own gardens and trying to design with them more.