You’d never guess it from the utter lack of publicity it’s received, but 2010 is officially the United Nations International Year of Biodiversity. The term “biodiversity” gets bandied around a lot these days (including in Secret Garden!), but what does it actually mean?
Simply put, biodiversity is short for “biological diversity”. It describes the total range of life-forms within a given ecosystem or biome, and suggests that the more biodiverse an ecosystem, the more resilient it is to disruption. In geographical terms, tropical biomes along the equator tend to be the most biodiverse on earth, while the poles tend to be the least biodiverse.
From my point of view as a passionate home gardener, biodiversity has three main implications – habitat creation/preservation, resistance to pests and disease, and conservation of genetic diversity. Let’s look at each of them in turn.
Habitat Creation/Preservation
We share our gardens with all kinds of life forms, from soil dwelling micro-organisms to native animals. As such, I believe we have a moral responsibility to preserve habitat for native species where it already exists, and where it doesn’t exist, to create new habitat.
Habitat creation isn’t too difficult. Mostly it involves a change of attitude that is more tolerant and inclusive of species other than Homo sapiens. Beyond that, it is largely about providing water, shelter and food for native animals by planting a diversity of species that are either indigenous to your area, or well suited to your particular climate. I’m not a native plant fanatic, favouring instead an eclectic garden full of plants from all over the world, but I do think it’s important to set aside at least part of the garden for “the birds”.
Resistance to Pests and Disease
The internationally renowned garden designer Paul Bangay, who was in Toowoomba last year, is famous for using a plant palette consisting of just a handful of species. In one of his books, he says that “I love those occasions when a site gives me the opportunity to use only two kinds of plant or even one, but lots of that one or two.” While Bangay’s gardens are undeniably elegant, his statements from a biodiversity point of view are way off the mark.
Let’s cut to the chase: the fewer the number of plant species within a garden, the more vulnerable it is to attack from every pest and disease under the sun. And as a consequence of limited diversity, the more necessary it is to drench the garden in chemicals to keep it healthy. If you want to reduce, or eliminate your use of toxic chemicals in the garden, the quickest way to shoot yourself in the foot is to “use only two kinds of plant or even one”. In agriculture, this would be called a monoculture. Biodiverse gardens comprised of many plant species are more likely to be healthy gardens.
Conserving Genetic Diversity
Consider, if you will, the humble spud. For centuries it has been one of the most important, and reliable, foodstuffs eaten by human beings, to the point that the International Potato Centre in Peru maintains a collection of about 5,000 individual varieties.
Now consider the Irish Potato Famine. By the mid 1800’s, the Irish had been growing the potato for more than 200 years. But due to a range of social and political factors, the lower classes of the population had become almost entirely dependant on the plant for food, with a single variety in particular dominating plantings across the country.
The Lumper tasted awful, but was nutritious and had the virtue of producing very heavy yields per acre. It’s major vice was that it was disease prone, and in the autumn of 1845, the fungal disease “late blight” wiped out the nations entire crop. Approximately one million people died from starvation and disease, a quarter of the population.
The moral of the story is simple, yet profound. Reduce genetic diversity far enough, and there’s a very real risk of starvation. Conversely, increase and preserve genetic diversity and food becomes more secure. It also becomes more democratic. The seed of heirloom varieties can be saved, and distributed to friends, increasing the gene pool even further.
I’d encourage each of you to celebrate the International Year of Biodiversity in your own backyard. Set aside a part of the garden where you can plant Australian natives to provide habitat. Rethink the minimalist approach to garden design in the light that the shelves in your garden shed will inevitably groan with poisons. Grow old fashioned fruit and vegetable varieties. Do your bit to preserve the genetic diversity of our food producing plants, and enjoy the myriad of flavours, colours, textures and origins as part of the bargain.
First published in the Toowoomba Chronicle 19th June 2010. Photo by Justin Russell – Roberta’s Garden, Pittsworth.
