Tuesday, January 22, 2013

Why should I care about biodiversity?

How to simplify a prairie, and why we shouldn't

In the last post, I just touched on the astounding diversity of life on Earth. As humans manipulate natural environments, we tend to simplify them – reducing the complexity of the vegetation and number of species of everything to such a degree that, in some places, only a few living things survive.

in the cornfield. photo: Lars Ploughman

Robert Krulwich’s review of Craig Childs’ book, “Apocalyptic planet; field guide to the everending earth” describes how Childs found “almost nothing” living in a cornfield in Iowa. Krulwich writes: “Cornfields...are not like national parks or virgin forests. Corn farmers champion corn. Anything that might eat corn, hurt corn, bother corn, is killed....” In and around the corn stalks, sitting on what was one of the world’s richest soils, was a denuded landscape with no birds, no bees, no buzzing insects, just a single plant species (corn), 1 small mushroom, 1 ant, and 1 red mite (just 2 arthropods!!).

The downgrading is pretty depressing. This loss of biological diversity eliminates or decreases pretty essential ecological interactions and processes (aka ecosystem services), such as providing food, energy and minerals, filtering water, capturing and storing carbon dioxide, dispersing seeds, and pollinating crops.

bees pollinating basil
photo: Matt Mets

bee pollinating onion
photo: Gary Halvorson, Oregon State Archives

For example, as native forest, shrub, and prairie is cleared, fewer wild bees survive, which cuts pollination not only of wild plants but also of many key human crops (note the bees in these 2 photos). Similarly, as different earthworm species disappear with the loss of forest, soil formation does too.

But how valuable is pollination or soil formation?  Read on!

More valuable than you might think

Since we humans think mainly in economic terms, these ecosystem services and their providers are generally unappreciated.

But picture paying a private company to perform the same cleaning and provisioning services -- e.g. waste decomposition, water filtration, food production, air conditioning -- that our biosphere currently does without charging a penny. It would cost roughly US $33 trillion, assuming we could actually recreate all the ecosystem services we have grown to know and expect (seriously, take a look at all the benefits our environment provides if you aren't familiar with this term).

economic value of the services provided by 13 ecosystems
(think water flow & filtration, timber, production of fish and other food, among other benefits)
image: Riccardo Pravettoni, UNEP/GRID-Arendal

But ecological systems are complex and interconnected. Trees that provide us with shade or fruit need their flowers pollinated and their seeds dispersed, while many of the bees, birds, and bats that pollinate our crops need trees and other native vegetation for breeding and survival during non-feeding hours.

image: sboisvert, Flickr
Think of an ecosystem as a brick building: you might be able to pull out a number of individual bricks here or there, but lose too many, or lose certain bricks in key locations, and you might bring down the whole structure.

Could we reproduce seed dispersal, nutrient cycling through plants and soil, carbon dioxide storage, and natural pest control quickly and at a large enough scale if these natural services disappeared?

We already manufacture seawalls and other coastal storm protections, water purifiers, genetically modified crops, and other products meant to do the job of some of the services provided naturally by the diversity of organisms around us. Perhaps some of you know of strategies being developed to emulate other ecological processes?

By helping to maintain functioning systems, biological diversity improves our collective global fitness. Any thoughts on other ways diversity contributes to higher collective biological fitness?

No comments:

Post a Comment