Bringing Nature Home

One of my children's most watched films is 'The Lorax', based on the book of the same name by the famous author, Dr. Seuss.  It is a fable chronicling the plight of the environment as the 'Oncer-ler', a character representing corporate greed, strips the land of natural resources for production of a 'Thneed'.

It highlights the dangers of unsustainable growth as the last 'Truffula' tree (the Once-ler's major raw material), is cut down forcing the Once'lers factory to close. In the mean time, all the wildlife that coexisted with the Truffula trees becomes displaced as their environment is filled with toxic pollution.

This past weekend, I jumped at the chance of taking my daughter to meet a real life Lorax, who like Dr Seuss was 'giving voice to the trees for they have no tongue'.   Doug Tallamy, who I featured in a post entitled America's Top Gardeners is a Professor of  Entomology and Wildlife Ecology for the University of Delaware. He was in town to talk about award winning book, 'Bringing Nature Home', and to address the plight of our own environment. What I discovered during the presentation was a revelation, that my own gardening philosophy was causing more harm than good.

Bluebird with caterpiller

Flickr.com - kansasphoto

Tallamy discussed that 96% of bird life relied heavily on insects, mostly caterpillars, to feed their young. These protein rich morsels contains pound for pound more protein of beef that allows chicks to develop quickly. However, this food supply has been declining, adversely effecting everything within the food-web. So frightening is the rate of decline that since 1966 we've seen a drop of 1% per year of migratory birds who over winter in Central and South America. That is a 50% reduction in 50 years! Habitat loss is one area of concern but failing food-webs are the other.

As we all know, most insects feed on the foliage of plants. Plants are able to capture the energy of the sun, while insects are very good at converting this plant tissue into other types of energy, in the form of themselves. But, plants are smart. Many plants produce toxins to prevent being striped of foliage, which would lead to their demise. As a result, selected insects have co-evolved with selected plants to become exclusive consumers, resistant to the toxin that would otherwise kill them. The down side to this specialism is that when food plants become endangered, then the insect can't adapted to new sources and declines in numbers. This limiting factor then effects the next level up that relies on the insect for food, triggering a collapse of the  food-web.

Monarch Caterpiller
Flickr.com - mean and pinchy

One example Tallamy used was the demise of the Monarch butterfly. The Monarch caterpillar only feeds from the foliage of milkweeds, Asclepias sp. For a long time, both milkweeds and monarch could be found in mass numbers among crops grown for agriculture. However with hybridizing, many of our crops have been bred to resist damage from herbicide spraying, funneling more nutrients to the intended crops but eliminating the population of milkweeds that would have grown wild in our fields.  96.4% of migrating Monarchs have gone, leaving only 3.6% of what that number was. Apart from Monarchs, 11 other butterfly species are known to reproduce on Milkweeds.

The last stand of the Monarchs
Flickr.com - Henry McLin

New sanctuaries have to be found if change is going to occur and Tallamy's answer is our gardens. Plants are the lifeblood of earth but our gardens have always been designed as status symbols. In America, nearly 45 million square acres (3 times more than irrigated corn crops) of lawns are grown, fed and watered for purely aesthetic reasoning. However, lawns don't filter water, don't provide clean air and don't support wildlife. We also fill are gardens with exotic, non native plants that are impervious to insect damage or spray harmful chemicals to ward off attacks.  In theory are gardens have becoming food deserts, unable to support live. Tallamy's suggestion was to take some of this area and convert it back.

"If half of American lawns were replaced with native plants, we would create the equivalent of a 20 million acre national park – nine times bigger than Yellowstone, or 100 times bigger than Shenandoah National Park."

Doug Tallamy

One example Tallamy used was of a courtyard garden (15ft x 15ft) found growing at the Department of Agriculture in Delaware. The garden contained just four plants of milkweeds but were found to be supporting over 150 monarch caterpillars. With such a small area set aside for native plants, it had become an island where a threaten population could find a haven.

'Native plants support native insects' was Tallamy's clear message. If you want birds you have to have a food source for them. In turn, to provide a food source for birds you need plants that are hosts to insects. The dilemma for a gardener is to except that your prized plant will at some point be nibbled on but the payoff is greater than the worth. An oak can support up to 550 different species of butterflies and moths which in turn provides food for birds, while an invasive Norway Maple is food for none.

I've learnt that by filling my garden with exotic, non-native plants that insect don't feed on, I have produced an environment of little value with green statues everywhere. This coming year I will be changing some of my planting to include more wildlife friendly, native plants. It would be a sad day if a stroll in the garden didn't include the song of a bird or the fluttering colors of butterfly wings, Unless.....

“But now," says the Once-ler, "now that you're here, the word of the Lorax seems perfectly clear. UNLESS someone like you cares a whole awful lot, nothing is going to get better. It's not.” 

― Dr. Seuss, The Lorax

Check out Doug Tallamy website by clicking here