Katrina rated largest U.S. ecodisaster
The hurricane destroyed or damaged about 320 million trees across the South.
By Patrik Jonsson | Staff writer of The Christian Science Monitorfrom the November 19, 2007 edition
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ATLANTA - No surprise: They love trees in Poplarville, Miss.
So when hurricane Katrina ripped out tulip poplars, bent black gum to the ground, and scattered loblolly pines like pick-up sticks, local tree enthusiasts such as Julia Anderson not only had a rude aesthetic shock, but many also sensed that the destruction had shaken the very roots of the region's ecological balance.
Now, scientists using NASA satellite imagery have at least partly confirmed those suspicions. From vast slash pine plantations to river-bottom hardwood stands, hurricane Katrina killed or damaged about 320 million trees across Florida, Mississippi, Louisiana, Alabama, and Texas – the largest ecological disaster in US history, new estimates reveal. Confronting a potential 100 million metric tons of greenhouse gases seeping from rotting logs and leaves, the proliferation of nonnative plants, and a spike in wildfire risks, scientists and residents alike are raising new questions about the storm's environmental legacy.
Perhaps the most critical one: Can Katrina-like storms contribute to an ecological "feedback loop," in which carbon being released from fallen, decaying forests raises the occurrences of storms and, in turn, intensifies the effects of global warming? The good news is that resilient and fast-growing Southern forests, with the help of humans, may be able to temper the phenomenon.
"The problem with feedback is that it'll make climate change worse than the current scenarios are envisioning," says George Hurtt, a natural-resources professor at the University of New Hampshire in Durham and coauthor of a new damage assessment published Friday in the journal Science. "Katrina left a huge carbon footprint, and there are going to be constant reminders of that."
The storm killed or damaged nearly one big tree for every American, and the total load of carbon dioxide produced by their decay surpasses the amount of CO2 that all healthy forests in the US could photosynthesize back into oxygen in a year's time. Moreover, a recent Louisiana State University study showed that, across history, wildfires have consumed hurricane-wrecked areas on the Gulf Coast. Such fires, too, can play into the carbon feedback loop, says Professor Hurtt.
At the same time, escaped Asian ornamentals – including Chinese tallow, the pesky privet bush, and congongrass (a forest-floor bully that swamps all competitors) – will probably complicate or delay regrowth in some parts of the forest.
"It actually is hard to find a silver lining," says Jim Shephard, a forestry professor at Mississippi State University (MSU) in Starkville.
Some critics, however, say that in their reach to connect Katrina's damage to global warming, researchers from UNH and Tulane University in New Orleans may have done better by employing forestry techniques such as on-site surveys.
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