Archive for January, 2012

A toucan is a toucan, right? And if a toucan landed on a nearby fence post, it would not be particularly hard to identify. “There’s a toucan!” you would shout giddily. No need to go running for the bird book.

By Elena Newmark, age 16

However, if you happen to be in Costa Rica when this toucan appears, you’ll find that when you smugly paw through the bird book to confirm your sighting (“Ha! Toucan! I knew it!”) there are, in fact, six different kinds of toucans. Unless you have an excellent memory for details, you have little chance of correctly identifying the critter.

I know this to be true because it happened to me last spring on a trip to the aforementioned tropical country.

Here in New England, if you see a small blue bird, flitting about like a chip of sapphire, there’s no messing around: it’s an Indigo Bunting. In Costa Rica, there are piles of brilliant blue birds to confuse you. Here, every hummingbird is a Ruby-throated. In Costa Rica, a hummingbird could sit on top of your binoculars laughing its head off and you still might not be able to identify it. This also happened to me. Costa Rica is home to 50 different species of hummingbirds.

A Costa Rican jungle is biodiversity in action. The biodiversity of a region refers to the number of different types of life forms it contains, from the smallest microbes and insects to the tallest trees and biggest predators.

The tiny country of Costa Rica, at approximately half the size of Maine, is one of the world’s biodiversity hotspots. Fully 10% of all existing bird species live there or pass through on migratory routes. The forests and surrounding oceans brim with an astounding variety of plants, fish, mammals, amphibians and reptiles.

On the country’s Pacific coast, the lowland rainforest of Corcovado has one of the densest concentrations of different species on the planet. We spent three days trekking through this jungle and indeed the place was crawling, creeping, and exploding with life. Snakes slithered from our footsteps, peccaries snorted in the underbrush, monkeys threw sticks, tapirs roamed the beaches, scarlet macaws screamed through the dawn, ticks chomped, and plants dripped into our path.

Despite the apparent health of ecosystems such as this, the planet today is losing species at an astounding rate. The International Union for the Conservation of Nature, a collaboration between hundreds of governmental and non-governmental organizations worldwide, estimates the current rate of extinctions to be 1,000-10,000 times more than it would be naturally. Human activities such as habitat destruction, agricultural practices, introduction of invasive species, and over-harvesting of resources, are the primary driving forces.

Renowned Pulitzer-Prize winning biologist E.O. Wilson has written that significant loss of biodiversity poses threats to the fabric of life which equal or surpass even those posed by climate change. Many scientists believe we are standing on the brink of the sixth great mass extinction in the history of the planet Earth. The last mass extinction, probably caused by a meteorite strike, occurred 65 million years ago and wiped out the dinosaurs. Rebuilding biodiversity after such an event can take millions of years.

Why does biodiversity have such profound implications for the ability of life to survive? Change is inevitable in any living system: climate patterns shift, diseases appear, new species turn up while others drop out. Ecosystems rely on biodiversity to remain productive and healthy throughout these changes.

When I was a teenager a freak wind storm caused major damage to every one of the line of gorgeous cherry trees planted along my city street. My mother wondered why they picked a variety so prone to wind damage. In actuality, the problem was the planting of a large number of the same tree. One year there may be ferocious wind, the next year terrible drought or a beetle that eats only ash trees. A mix of plantings increases the odds that some trees will survive and thrive.

When Dutch Elm Disease struck the United States around the middle of the last century, many communities lost more than half of their urban street trees. In part because of this legacy foresters now recommend planting a large variety of species to prevent losses of the same magnitude from unforeseen future stressors.

It is also true that the greater the variety within each species, the greater the chance that some individuals of that species will be able to weather adversities and pass their strengths along to their children. The fewer individuals left of a given species, the less health and vigor is seen in the entire population.

The planet’s environment is being altered at a staggering rate at the same time that our actions are dramatically diminishing the variety of lifeforms, thereby also reducing the ability of plants and animals to adapt to change.

This loss of diversity isn’t just a problem for peccaries in the rainforest: it poses threats to the health of the agricultural crops that we depend on for food, our ability to discover new treatments for disease, and the functioning of the natural systems that regulate carbon, oxygen and water.

Many cutting-edge techniques such as genetic engineering, in which desirable traits from one organism are transferred into another organism, rely on nature to invent the desirable traits in the first place. Modern science draws constantly from the vast pool of chemicals manufactured by the world’s plant and animal life to devise new medicines.

Even at the horizons of human inventiveness, we still depend on the natural variability that comes from a rich and diverse pool of species with many individuals flitting through the trees, creeping along the ground, and growing out of the cracks.

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