Completion of the Vierra Restoration Project at the San Joaquin River NWR
By Tom Griggs, Ph.D., Senior Restoration Ecologist
The Vierra project was the first time that River Partners designed and implemented a riparian restoration that involved a wetland—311 acres of woody vegetation with understory surrounding 200 acres of seasonal wetland. This is exciting to the planner because of the opportunity to design two very different plant communities in the same project.
When we got the green light to begin field work, we were just about finished with planting the first half of the acres when the flood of 2006 occurred. This flood started in March and eventually covered most of the San Joaquin River Refuge for five months, finally draining away in early August. The aftermath was very interesting if you are a scientist: some plant species fared very well (Oregon ash, black and sandbar willow, valley oak, Fremont cottonwood), while other species completely died out as a result of the long duration flooding (Coyote brush, elderberry, box-elder).
As a result we re-designed the Vierra planting to add more flood-tolerant species, as this type of flood will likely happen again. (The last time the Refuge flooded in the spring and summer was 1998.) The Refuge realized that this type of long duration flooding would be a problem for riparian brush rabbit survival. As a result the Refuge funded the construction of high mound flood-refugia for the riparian brush rabbit and other terrestrial animals. River Partners planted the mounds with a dense planting of rose and blackberry to protect the animals. River Partners also secured funding to plant the sides of the soon-to-be decommissioned levees surrounding the project as additional flood refugia for wildlife.
At this writing (Nov 2008) the Vierra project has developed into a healthy young riparian planting. Near future activities include the final breaching of levees as part of the U.S. Army Corps of Engineers non-structural flood control project that will help reduce flood depths in the region. This flooding will benefit the Vierra plantings in the future, allowing them to develop into a complex riparian habitat for many species of wildlife.