The value of vernal pools

Upcoming conference explores whether they can be conserved and restored

Mr. Alexander is retired from teaching biology at Chico State University, where he was an expert on vernal pools.

Vernal-pool landscapes are found in few places around the world and threatened where they do exist. We are fortunate in Butte County to have some of the last remaining vernal-pool landscapes in California.

Vernal pools are formed when winter rains fill puddles, temporary creeks and pools atop impermeable, hard-clay soils. The spring (vernal) colors show us that plants blooming across the fields are different from plants in drainage channels and those along drying pool edges that are replacing the last surface water as it evaporates in summer’s heat. Other plants grow only in dry summer basins, long after migrating ducks and geese are only memories.

My students and I studied small animals living in the temporary pools. Many of these animals start growth in the winter and complete development before flowers replace the water. Crustaceans, including fairy and tadpole shrimp, survive the summer in cysts buried in the ground. Snails move into drying sediments and survive because water is sealed inside their shells. Many insects fly to other habitats.

The kinds and numbers of aquatic animals are affected by unpredictable aquatic life as well as the absence of fish, large numbers of water birds, insect and invertebrate predators and, in some pools, the young of frogs, toads and salamanders.

Urbanization and the establishment of orchards and vineyards have destroyed many vernal-pool landscapes. This loss has forced state and federal resource agencies to declare protective status for some vernal-pool organisms and their dwindling habitats. As a result, some development has been stopped and other activities have required compensation.

This compensation has included the establishment of preserves. Unfortunately, these preserves are often small, surrounded by city development, and poorly funded. Although we have lost vernal-pool landscapes in and around Chico, some remaining areas, including parts of Bidwell Park, could become important vernal-pool preserves.

Vina Plains Preserve, managed by The Nature Conservancy, is a large landscape jewel you can enjoy by driving north on Highway 99.

The group AquAlliance is sponsoring “Vernal Pool Conservation: Research, Progress and Problems. Is Recovery Possible?” in The Big Room at Sierra Nevada Brewing Co., on Thursday, March 25, followed by a banquet and a field trip the following day. For anyone interested in vernal pools and their preservation, it will be an invaluable opportunity to learn more and network. Register at