Jeffrey Q. Chambers is the lead author in an article in Science, dated 16 November, reporting findings that Katrina destroyed or seriously damaged
320 million large trees totaling 105 teragrams of carbon, representing 50 to 140% of the net annual U.S. forest tree carbon sink. Changes in disturbance regimes from increased storm activity expected under a warming climate will reduce forest biomass stocks, increase ecosystem respiration, and may represent an important positive feedback mechanism to elevated atmospheric carbon dioxide.
Link to Science abstract of“Hurricane Katrina’s Carbon Footprint on U.S. Gulf Coast Forests” — Chambers et al. 318 (5853): 1107; subscription required for full text.
Thomas H. Maugh II and Karen Kaplan’s coverage in the Los Angeles Times is excellent. Please read to the bottom of this excerpt – they’ve gone far enough to identify what, to my mind, is the most frightening detail in the story. The lost trees are already being replaced by invasive species; the implications are (1) we can’t just let it grow back (2) the longer we wait to reforest, the harder it will be.
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 U.S. 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 U.S. forest fires.
“This is a one-shot massive hit to these systems, where you see this enormous impact,” said Jason Neff, an assistant professor of geoscience at the University of Colorado at Boulder, who was not involved in the study.
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, which made landfall in August 2005 with winds that reached 125 mph, damaged 5 million acres of forests, 80% of them in Mississippi, according to the U.S. Forest Service. By comparison, the 1980 eruption in Washington of Mt. St. Helens wiped out 150,000 acres of forest.
“In some areas of southeast Louisiana and southeast Mississippi, it was 100% damage,” said Wayne Hagan, founder of Timberland Management Services of Louisiana in Clinton. “I had one landowner on 2,000 acres who had basically $4 million worth of trees on his place. One hundred percent of the trees were blown over and broken down. That’s basically what the hurricane did.”
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.