Hurricanes Katrina and Rita added to Global Greenhouse Gas Buildup

New satellite imaging has revealed that Hurricanes Katrina and Rita produced the largest single forestry disaster on record in the nation -- an essentially unreported ecological catastrophe that killed or severely damaged about 320 million trees in Mississippi and Louisiana.

The die-off, caused initially by wind and later by weeks-long pooling of stagnant water, was so massive that researchers say it will add significantly to the global greenhouse gas buildup -- ultimately putting as much carbon from dying vegetation into the air as the rest of the nation's forests take out in a year of photosynthesis.

In addition, the downing of so many trees has opened vast and sometimes fragile tracts to several aggressive and fast-growing exotic species that are already squeezing out more environmentally productive native species.

Efforts to limit the damage have been handicapped by the ineffectiveness of a $504 million federal program to help Gulf Coast landowners replant and fight the invasive species. Congress appropriated the money in 2005 -- the year the hurricanes hit -- and added to it in 2007. But officials acknowledge that the program got off to a slow start and only about $70 million has been promised or dispensed so far. Local advocates said onerous bureaucratic hurdles and low compensation rates are major reasons why.