BergerWorld: 2nd Quarter 2006

Vernal pools, seasonally filled ponds or shallow lakes that flood in the spring and dry up in late summer and winter, are no less significant ecologically than other types of wetland habitats. In fact, it is the very intermittent nature of these pools that make them so important ecologically, providing a unique niche for many species, particularly amphibians. Frogs and salamanders find vernal pools a fishless paradise-an ideal habitat for laying eggs and a safe haven for developing tadpoles. After pioneering successes in vernal pool construction as mitigation sites for Interchange 1 of the New Jersey Turnpike, a U.S. Penitentiary in California and Stewart Airport in New York State, Berger continues to be at the forefront of this important new approach to habitat restoration.

For the New Jersey Department of Transportation (NJDOT) improvements along NJ Route 183, Sussex County, Berger proposed an extensive wetland mitigation program. Following a detailed study of the Musconetcong River watershed, the Berger team identified one on-site and one off-site location that met the required mitigation acreage, and prepared designs and contract documents for the construction of both areas. The forested on-site area included vernal pools and a restored trout stream, while the off-site area included three wetland plant communities-seasonally saturated forest, scrub/shrub and emergent marsh supporting amphibian breeding. Since the off-site area was situated near Byram Township Intermediate School, a unique educational opportunity presented itself. At NJDOT's request, Berger incorporated suggestions from the school faculty and the NJDEP's Bureau of Parks and Forestry into the design of a nature trail with kiosks, interpretive signs, benches, picnic tables and bird blinds. Berger subsequently monitored the wetland construction.

The biology department at Davidson College proposed the installation of six vernal pools to provide an outdoor classroom allowing students and researchers to observe firsthand this fascinating type of wetland. The North Carolina Department of Environmental and Natural Resources selected Berger to design the pools at the Davidson College Ecological Preserve. The Berger team assessed and evaluated site hydrology, land use issues, possible hazardous waste contamination, the presence of endangered and threatened species on the site, and prepared final plans for the pools.

During the preparation of an Environmental Impact Statement for the construction of a U.S. Penitentiary in Southern California, federal and state wildlife agencies expressed concerns regarding the presence of the federally endangered California tiger salamander.

In response, Berger conducted habitat assessments and population surveys. Growing to 4.5 inches and only breeding in vernal pools below 600-meter elevations, the California tiger salamander is one of the seven recognized subspecies of tiger salamander found throughout the western United States, and the only one found natively in California. It is thought that imported subspecies compete and breed with native California tiger salamander. Following U.S. Fish and Wildlife Service (USFWS) protocols, visual nighttime and aquatic sampling were conducted to determine if native California tiger salamanders were present on the site, including three pools suitable for breeding. Although tiger salamanders were not observed during the nighttime surveys, they were found within two of the wetlands during the aquatic survey.

Since the larval form of tiger salamanders could not be distinguished, the larvae were sent to the University of California-Davis for genetic testing showing conclusively that the specimens were neither tiger salamanders nor hybrids. The findings suggest that California tiger salamanders were never at the site or have been extirpated. Assisted by Berger, the USFWS subsequently collected non-native salamanders to reduce the chance of interbreeding between the two species.