Wednesday, February 20, 2008

What are we doing out here?

"Forests are the lungs of our land, purifying the air and giving fresh strength to our people."
-Franklin D. Roosevelt

What are we doing out here? We come in with big yellow machinery, excavators and bulldozers and trucks, and lay waste to what we call unnatural and bad, to create a new ecosystem that we call good and natural. The alternative is accepting ecosystem "replacement" AKA ecological succession. Who can weigh all the ramifications of change to decide what is good and bad? How can we attempt to control what we don't understand? Is invasive species removal worth it?

For most of the riparian areas in the Southwest, the invasive species of focus is tamarisk:

"Tamarisk can usually out-compete native plants for water. A single, large tamarisk can transpire up to 300 gallons of water per day. In many areas where watercourses are small or intermittent and tamarisk has taken hold, it can severely limit the available water, or even dry up a water source.

Tamarisk can grow in salty soil because it can eliminate excess salt from the tips of its leaves. When the leaves are shed, this salt increases the salinity of the soil, further reducing the ability of native plants to compete. Because of its ability to spread, its hardiness, its high water consumption, and its tendency to increase the salinity of the soil around it, the tamarisk has often completely displaced native plants in wetland areas.

From a wildlife point of view, the tamarisk has little value and is usually considered detrimental to native animals. The leaves, twigs and seeds are extremely low in nutrients, and, as a result, very few insects or wildlife will use them. In one study along the lower Colorado River, tamarisk stands supported less than 1% of the winter bird life that would be found in a native plant stand. Because of the tamarisk's ability to eliminate competition and form single-species thickets, wildlife populations have dropped dramatically." Source: White Sands National Monument

So is invasive species removal worth it? It seems that, in the case of tamarisk, the best available science says yes. So we come in with the big yellow machinery.

We're not against natural change but we are against destructive change, change that impoverishes rather than re-invigorates. According to David Brower, restoration is the opposite of trying to stop the hands of time; it is an effort to keep the clock running: "The business of making something better, getting something back in shape--helping Nature heal--should make us feel good. And it will probably make our children feel better about us if we spent more time trying." David Brower Wild Earth Interview, Spring 1998.

No comments: