Biologists are pioneering new approaches in the field of revegetation that are leading to faster growth rates, greater plant survivability and higher yields. The developments are proving useful in the mitigation of areas where large parts of the natural habitat have been disturbed.

A revegetation project currently being conducted by Woodard-Clyde Consultants provides a good example of how these new approaches are being employed. WCC is a nationwide firm of engineering, environmental and earth science consultants.

The project involves the Chula Vista Wildlife Reserve located in south San Diego Bay, California. It was established as a mitigation site to offset the loss of habitat resulting from the dredging of a small boat basin.

The reserve was created from dredge spoils. First, a series of dikes were built to form two adjacent basins. Then dredged material was pumped in and allowed to dewater for several years. Next, the basins were opened to tidal action and biologists began a series of plantings to develop a cordgrass marsh at the proper intertidal elevation. The plan was to create a marsh that could provide habitat for numerous water fowl, shore birds and song birds?EUR??,,????'??+including two endangered species?EUR??,,????'??+the light-footed clapper rail and Belding’s savannah sparrow.

Biologists designed a phased experimental approach. The first year’s planting was designed to establish areas in the two basins which would support cordgrass growth. The results of the initial transplant effort would then be utilized to design the final one.

Revegetation began with a comprehensive field survey. Soil salinity was measured at selected locations using a refractometer and the sediment was qualitatively characterized as to grain size and consistency. The information developed during this initial reconnaissance was then used along with data on soil nitrogen, pH and redox potential to develop the planting design

The initial planting design established four transects and one large nursery area in the western-most basin and five transects in the eastern basin. Plants taken from a nearby donor site were transplanted along the transects. Using plants from south San Diego Bay helped insure a greater survivability rate.

Several different combinations of planting techniques were used during the initial phase. Plants were assessed periodically through two growing seasons. By monitoring them closely, biologists were able to determine the most appropriate locations for establishing cordgrass. Slightly over 99 percent of the plants planted in March 1984 survived after the end of one growing season. And the plants established four years ago continue to exhibit a remarkable success.

What was once a barren mound of mud is now a thriving plant community and vital marsh, home to hundreds of birds, including dozens of great blue herons.

“It is a living laboratory,” said Ted Winfield, WCC project scientist. “The information that we’ve gained is proving invaluable, allowing us to gain knowledge.”