As families in three states continue to rebuild their homes and lives more than two years after Hurricane Katrina, comes word that Gulf Coast forests were also hard hit. Pictures taken from space by NASA satellites tell the story of how the monster storm damaged 320 million large trees across five million acres. Forest lands in Mississippi, Louisiana and Alabama, suffered damage ranging from downed trees, snapped trunks and broken limbs to stripped leaves.

The big concern in all of this is that the damage weakened the role the forests play in storing carbon from the atmosphere, leading to these forests releasing large quantities of carbon dioxide into the atmosphere. Young growing forests play a vital role in removing carbon dioxide, a greenhouse gas, from the atmosphere by photosynthesis, and are thus important in slowing a warming climate. More importantly, all the dead wood will be consumed by decomposers, resulting in a large carbon dioxide release to the atmosphere as the ecosystem exhales it as forest waste product.

Image above: Damaged forests in the Pearl River Basin along the Louisiana-Mississippi border were photographed from the air in late 2005. Resistant cypress and tupelo trees surround downed and dead hardwood forest trees such as oak, sweetgum and maple.

Photo Credit: Louisiana State University Hurricane Katrina & Rita Cooperative Clearinghouse.

“The loss of so many trees will cause these forests to be a net source of carbon dioxide to the atmosphere for years to come,” said the study’s lead author Jeffrey Chambers, a biologist at Tulane University in New Orleans, La. “If, as many believe, a warming climate causes a rise in the intensity of extreme events like Hurricane Katrina, we’re likely to see an increase in tree mortality, resulting in an elevated release of carbon by impacted forest ecosystems.”

Chambers and colleagues from the University of New Hampshire in Durham, N.H., studied Landsat 5 satellite data captured before and after Hurricane Katrina to pull together a reliable field sampling of tree deaths across the entire range of forests affected by Katrina. They found that some forests were heavily damaged while others like the cypress-tupelo swamp forests fared remarkably well.