An analysis of satellite imagery of the Gulf Coast region of the US shows that Hurricane Katrina destroyed an estimated 320 million trees in Mississippi and Louisiana, an unprecedented loss of forestland that will reshape the region for generations, Louisiana researchers said.

The death of the trees from wind damage and soaking in saltwater will ultimately release about 367 million tons of carbon dioxide as they decompose — about the same amount that is absorbed by all US forests in a year, according to the study published in the journal Science.

Considered on the vast scale of global climate change, Katrina’s impact is small. But as a one-time event, its infusion of carbon is significant, exceeding an entire season’s worth of emissions from US forest fires. Most of the lost trees in the Gulf region stood 70 to 100 feet tall, and others will not grow back for decades, if ever, experts said. Hurricane Katrina damaged 5 million acres of forests in August 2005, 80 per cent of them in Mississippi.

Biologist Jeffrey Q. Chambers of Tulane University and his colleagues said the deforested land, once covered with native species such as longleaf pine, oak and cypress, is being taken over by invasive species that are changing the ecology of the area. One of the most prolific, the Chinese tallow, oozes a milky, toxic sap that creates an inhospitable environment for insects, birds and small animals.

The trees that are growing back represent only a fraction of those destroyed, and they are surrounded by large quantities of decomposing lumber. Combined with the drought now punishing the South, that is the recipe for a devastating forest fire, said James L. Cummins, executive director of the Mississippi Fish and Wildlife Foundation.

... contd.