Saturday, February 7, 2015

Odds 'N Ends - A Broader View of Sustainability

The Food Chain Starts with Plants
Only plants are capable of converting the sun's energy into food (photosynthesis). Plant-eating insects and animals -- herbivores (with minor input from omnivores) -- convert plant tissue into animal tissue.  Without plants and plant-eaters, there would be no higher forms of life, including humans.  Unfortunately, many plants, insects and animals at the lower end of the food chain are on the road to extinction due to habitat loss and degradation.

In my opinion, anyone interested in a broader view of sustainability should read the eye-opening "Bringing Nature Home - How You Can Sustain Wildlife with Native Plants" by Douglas W. Tallamy, professor and chair of the Department of Entomology and Wildlife Ecology at the University of Delaware in Newark, Delaware.

Three Problems
The gist of the book is that plants capable of supporting the essential herbivores are under assault on three fronts.  First, habitat for natives has been replaced by agriculture, lumbering and urban sprawl (think herbicidal control of milkweed, the sole food for monarch butterflies, and loss of their winter habitat in Mexico due to illegal lumbering). Second, pests that hitch a ride on imported ornamentals cause extinction of natives (think chestnut blight, Dutch elm disease and Emerald Ash borer).  And finally, alien plants, with no natural enemies, out-compete natives (think Russian olive, Japanese honeysuckle and kudzu).

To make matters even worse, alien plants hog resources (nutrients, water and sunshine) but, since they are rarely eaten by native herbivores, contribute nothing to the food chain. The ubiquitous foundation plants, ornamental trees and shrubs, as well as cool weather grasses, are all problematic in this regard.

Habitat Fragmentation - Habitat Islands
Instead of the original thousands of acres of contiguous native habitat, the habitat remaining today is in the form of isolated islands that are usually degraded by alien invasives, foul air and chemical run-off.  "Bringing Nature Home" means gardening and landscaping with enough native plants to support wildlife.  Native trees, shrubs and prairie plants bridge between isolated islands and provide sustenance at the bottom of the food chain that may actually be better than that provided by the islands themselves, particularly in heavily populated areas.  

Native plants support native herbivores because the plants and insects/animals evolved together over millenia.  The native herbivores do not recognize alien plants as food and, if they were to be tempted, likely do not have the ability, bestowed by co-evolution, to overcome the plants' defense mechanisms.  A white oak tree, for example, supports 534 species of lepidoptera (moths and butterflies) while a Bradford pear tree or Japanese honeysuckle bush support practically none (Tallamy).

About half of Tallamy's book is advocative and half is helpful hints for getting started with natives and guidance on region-specific plant selection.  

Wild Ones ( is an organization that promotes landscaping with native plants and, of course, the eradication of non-natives.  As members for several years, Dorothy and I have visited many beautiful private and institutional native landscapes. And we have mingled with the choir -- a unique subset of interesting environmentalists who are only too happy to share, not only their knowledge, but plant seeds as well.

Our Progress
Although we are at least two years away from completion of our home, we have already eliminated most of the alien plants that overran the property initially. Our new natives are beginning to flourish in areas that will not be disturbed by the construction and their progeny will dominate after construction.

Fortunately, here in the hilly bluffs of the Mississippi River, the habitat fragmentation is less intense than in the surrounding countryside--more like peninsulas than islands. Our hope is that someday our 4+ acres of mostly natives will be a bridge between two adjacent (struggling) peninsulas.

Oh, by the way, did I mention that native gardens and grasses slow global warming? Yep, in two ways--by storing far more carbon than foreigners like fescue, zoysia or Japanese yews and by avoiding the carbon inputs of watering, fertilizing and mowing (Native plants and global warming).

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