Thursday, November 18, 2010

Santa Ana NWR Post-flood pictures - November 7, 2010

Santa Ana National Wildlife Refuge flooded in the summer of 2010 for the first time in over 50 years. Like so many areas in the Lower Rio Grande Valley, the riparian corridor and floodplain forests have been in need of floodwaters to deliver nutrients. With the regular flooding of the Rio Grande curtailed or diminished by dams including Falcon and Amistad dams and other dams in Mexico, the thorn forest has been replaced by thorn scrub as the tall trees die off. This summer's flood may be the first step in a rejuvenation of the thorn forest and riparian corridor on the Lower Rio Grande. The flood also sent huge mats of Arundo or giant cane and water hyacinth - invasive exotic plants - into the Gulf of Mexico. The Refuge is reopening for guided walks, be sure to see the revitalization of the forests for yourself!
This area below on the tour loop was not flooded as deep, but you can still see the impact on the guinea grass.
The view at Cattail Lakes was of one large pond . The levees subdividing the pond into various units were covered with water.
A branch of the river crossed the tour loop road here and cut into the gravel and soil on the right (east) side of the road. The drop off was 2-3 feet deep on the right side of the picture. Cattail Lakes again.
The forest is recovering quickly. The invasive exotic guinea grass was killed and the roots rotted after several weeks under water. Unfortunately, the grass is regenerating from the seed bank, but the refuge staff are making great efforts to control the guinea grass while it is more sensitive to grass-specific herbicides.
The tour road is still underwater from near the Resaca Trailhead to the Mesquite trail. The water was going down but there was still a lot of it.