"Bird watching and hunting are also huge economically," he noted, "and marshes also filter runoff from the mainland to provide cleaner water to the bays."
Feagin said the marshes also play a role in building new land because the plants slow down rising tide water, causing suspended sediment to settle, resulting in layers of land over time.
"Prior to Ike, we tested this near Galveston by killing the marsh plants in one area to compare surface elevation change with a nearby marsh where we left the plants alone," he said. "We found that the plants did help build land elevation prior to the hurricane."
However, when studying post-Ike surface erosion at the site, Feagin said, "we found the plants did not prevent sediment erosion by waves during Ike and in fact enhanced erosion because their roots wiggled, stirring up sediment to be washed out to sea.
"Some would say that plants directly protect the land and thus protect people from storms," Feagin said. "But that's not so in terms of the big storms. But the waves are not what does the damage and cause death, it's the water depth. If you get a 12-foot wall of water, it doesn't matter if you have a front yard full of oak trees.
"We need to rely on 'ecological engineering' and good policy that requires people to build homes in the correct locations," he said. "If we covered a barrier island such as Galveston with concrete, you could say it was stabilized. But without the natural process of building elevation through by plants, the whole thing will eventually drown from the rising sea level."
|Contact: Kathleen Phillips|
Texas A&M AgriLife Communications