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Doug Tallamy

Dr. Douglas Talamy is Professor and Chair of Entomology and Wildlife Ecology at the University of Delaware where he has studied insects and their role in the environment for over twenty years. Among his research areas are the impact of alien plants on native ecosystems, the interactions between plants and insects, and the conservation of biodiversity. He is the author of Bringing Nature Home: How You Can Sustain Wildlife with Native Plants (2007) published by Timber Press.

In his keynote address, Friday evening after the banquet at the 2013 Private Forest Conference, Dr. Talamy shared a very meaningful perspective on why, as caretakers of the forest community, we should commit to bringing back nature. To even the casual observer, alien invasive plants increasingly dominate parts of our forested landscape. Many of these alien plants came from distant shores and took up residence in our urban landscapes because they added new colors or textures, and were often “immune” to native insects and disease – they are easier to maintain. Others plants were touted for their conservation value – mast bearing or providing wonderful habitat. Sometimes, these aliens introduced other unwanted guests (e.g., chestnut blight, Dutch elm disease, emerald ash borer, hemlock wooly adelgid). Unknowingly, when we bring alien plants (even, plants from other parts of our own country) to new places, we may unwittingly set into motion new competitive situations where truly native species begin to lose. 

Dr. Talamy’s interests, as an entomologist, allowed him to spin an engaging story about the intersection of plants and insects. In his message, he explained how alien plants affect forest health, biodiversity, and can lead to local extinctions. In his major thesis, he explained how ecological community structure shifts as invasive or alien plants begin to infiltrate the landscape. Because many of these plants do not host native insects, they do not provide habitat for them – the insects do not feed or reproduce. From the perspective of wildlife, particularly birds, declining insect populations and diversity are especially problematic. Many bird species are very dependent on insect protein during the breeding season. This was an enlightening point. Most often foresters and landowners express concerns for retaining mast-producing plants. These are important, but are most important in late summer, fall, or winter, not during the spring when birds need high protein food.

In his presentation, he illuminated his point of how alien plants affect native birds by describing a field of autumn olive. He spoke of a chickadee foraging for insects and returning to the nest every three minutes with insect larvae. If the foraging time increased, only slightly by the bird’s inability to find the next “meal,” what would be the cost to its brood success? In a landscape dominated by alien plants, this is often the case. A bird nesting in a habitat dominated by autumn olive would have to forage over a much wider area to find critical insect protein for its nestlings. In a sense, this patch of autumn olive (or bush honeysuckle, privet, or many other species) is a food desert and forces nesting birds to change their feeding patterns and greatly increases their energy expenditure when foraging.

Dr. Talamy argued that we need to consider carefully how we landscape our property. He suggested that adding native species is not that difficult and that often the insects we wish to discourage by insistently planting non-native, easier to care for, alien species tend to impoverish our landscapes. The healthier mix of native species will support a wider diversity of species – fungi, plants, insects, and wildlife – than a sanitized landscape of alien species. It takes work to bring back the native species, but, in his opinion, it is worth the effort, even in our urbanizing environment, one house lot at a time. You can also learn more about Doug’s work by visiting his website at http://www.plantanative.com/.