04-15-2006 - Earth

This is Earth and Sky, on using satellites to detect logging in the Amazon rain forest – previously hidden to scientists.

Gregory Asner is a remote sensing expert at the Carnegie Institution of Washington. He said satellites used to lack the precision to see where people cut valuable individual trees – such as mahogany. Asner’s team found a way to refine the satellite images. Their images show that, each year in the rainforest, an area the size of Connecticut was being selectively logged.

Gregory Asner: And what it essentially tells us is that the area of disturbance in the Amazon is double now what we thought it was prior to our study.

That disturbance can take the form of other trees pulled down by those selectively logged. There are also roads built to reach the trees. And selective logging lets more light reach the forest floor, drying out the understory and creating fuel for fire.

Gregory Asner: So when people ask, is selective logging as large a form of damage as deforestation, the answer is no, initially, not nearly the same level of damage. But over the long run, the fact that fire is introduced to a place that really hasn’t had fire, historically, is a cause of great concern to the scientists that work there.

More about the human footprint in Amazon rainforests at earthsky.org. Thanks today to NASA – explore, discover, understand. We’re Block and Byrd for Earth and Sky.

Written by Deborah Byrd