Bringing Nature Home
When people tell me about their gardens, they often talk about their favorite plants. We all choose plants that please us because their flowers strike us as beautiful, because the array of various greens is pleasing and restful to our eye, or because they are attractive and will not require too much work on our part to remain healthy and attractive. These are all perfectly valid reasons for choosing plants for our domestic landscape, but according to Douglas Tallamy, Chair of the Department of Entomology and Wildlife Ecology at the University of Delaware, in his new book from Timber Press, Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens, such choices don’t reflect the need of our gardens for “native plants to support a diverse and balanced food web essential to all sustainable ecosystems.”
This book emphasizes the importance of suburban gardens to the intricate food web that supports the insects, birds, toads and all other animals native to our areas. The book looks very serious and it is full of Latin names, but every page is fascinating. Tallamy starts with very simple facts that seem new. “Nearly every creature on this planet owes its existence to plants, the only organisms capable of capturing the sun’s energy and, through photosynthesis, turning that energy into food for the rest of us.”
I’ve been known to carry on about the interconnectedness of all things, but I have never been given such a clear explanation of the intricacies of the food web as Tallamy gives. To start us off he asks several questions like “What good is biodiversity? And “How does the quality of human life differ in simple and complex ecosystems?” The answers are not simple, but they are presented in an accessible and engaging way. He includes his own experiences and adventures with the landscape.
We may think about our own food, but not spend too much time thinking about
the food that insects, birds and animals need. Nor do we think about why those
creatures need specific plants. Tallamy devotes a whole chapter to the question
Why Can’t Insects
Eat Alien Plants? The first answer is that landscapers have understandably
been drawn to plant that are unattractive to insects. Secondly, it takes a
long time for an insect to “adapt to the specific chemical mix that characterizes
different plants.” The third reason is related. Many insects can only eat
plants that developed with them in evolutionary time and some are extremely
specialized.
Since alien plants that escape into the wild are often vigorous growers they overtake and kill native plants. Thus, those aliens can destroy nesting and shelter sites and interrupt the food web.
Tallamy explains that when alien plants are brought into this country as ornamentals they can bring with them serious pests. He gives the example of the Chinese and Japanese buckthorns which arrived carrying the soybean aphid. Since 2000 this pest has caused hundreds of millions of dollars of soybean crop reductions.
Another threat of escaped alien ornamentals is that they can hybridize with our native plants and this can “alter the frequency of wildfires and the availability of surface or groundwater, decrease the diversity of soil biota, deplete soil nutrients, degrade aquatic habitats through soil erosion. . ..”
The goal we have to work towards is a balanced community and ecosystem in our own gardens. This requires complexity, a “food web with many levels and much redundancy, just as we would find in nature.” It is with plants that we can start to build this balanced system with its redundancies that provide support.
He says that he often finds it a hard sell to promote native plantings by saying that they will attract more insects, but the point is that with a greater variety of insects you get more predators that will keep pest populations under control without the use of pesticides.
Tallamy includes wonderful chapters on supporting butterflies which means supplying host plants for larvae as well as nectar plants for the adults. He even gives very specific information about what kinds of host plants will attract specific butterflies.
Another chapter is given over to feeding the birds, with special emphasis on the insects that birds eat. Did I know that all birds, even seed and berry eaters, feed their nestlings insects? No.
There is lots of attention paid to various endangered species of animals, but endangered plants and insects don’t get the high profile publicity of cougars and gray wolves. Tallamy paints a gloomy picture of how quickly all native wildlife in the United States could disappear forever, but he also says that since the destruction of food, shelter and nesting sites needed by animals has been removed because of a lack of thought, not because we need to, we can create sustainable ecosystems that will increase the diversity of species right in our own backyards.
Does this mean our backyards need to look like an unattractive weedy wilderness? Absolutely not.
Tallamy gives lists of native plants that are attractive and suitable for our gardens and reminds us that groundcovers, shrubs and trees together can make for a beautiful arrangement as well as a more complex and useful arrangement than lots of lawn with a specimen tree or two.
I garden without pesticides on a mixed landscape of woodland and meadow. I fight invasives like multiflora roses and Russian olive and will continue with renewed energy.
Tallamy sounds the alarm, but he is optimistic. Hr reminds us that biodiversity is a renewable resource. Biodiversity needs to be managed like any resource, clean air and water. The suburban landscape is a huge percentage of the developed landscape and the suburban gardener has an important responsibility and opportunity to protect and increase the biodiversity of his own domestic landscape. It will be beautiful and healthy.
November 2007