Contributed by Len McKenzie —
Generous rains this winter have spawned a luxuriant rebirth of plant life in the Sierra foothills and Central Valley, greening up the landscape and bringing renewed vigor to its ecosystems. Beneficiaries of this largesse include the picturesque and biologically rich vernal pools that are a distinctive hallmark of this remarkable setting.
The Yosemite Area Audubon Society will showcase the biodiversity within and around these rare seasonal ponds in a slide presentation, “Vernal Pools: Not Just Puddles,” by Monique Kolster, director of the UC Merced Vernal Pools and Grassland Reserve, at 7 p.m. on Thursday, February 9, at the Mariposa Methodist Church parish hall on 6th Street in downtown Mariposa.
Vernal pools are shallow, seasonally flooded depressions in soil with an impermeable hardpan layer beneath the surface that allows the pools to hold water longer than the adjacent uplands during the rainy season. They are shallow enough that they dry up after the rains stop, and only plants and animals adapted to this seasonal wet/dry cycle, including a number of endangered species, can survive over time.
The ecological cycle of these pools is extraordinary. According to the California Natural Resources Agency, “These specialized plants and animals are what make vernal pools unique. As winter rains fill the pools, freshwater invertebrates, crustaceans, and amphibians emerge. Vernal pool plants sprout underwater, some using special floating leaves and air-filled stems to stay afloat. Some of these plants even flower underwater! Birds arrive to feed on the vernal pool plants and animals.
“In spring, flowering plants produce the brightly-colored concentric rings of flowers that vernal pools are famous for. Native bees nest in vernal pools and pollinate pool flowers. Insects and crustaceans produce cysts and eggs, and plants produce seeds that are buried in the muddy pool bottom. The mud protects cysts, eggs, and seeds from the hot, dry Central Valley summer.
By late summer, amphibians have dug deep into the soils and gone dormant, awaiting the next rainy season. Vernal pools have completely dried out and most of the plant and animal species have either disappeared into the soils or set seed and died.”
Kolster will provide an ecological overview of vernal pools with an emphasis on their importance as habitat, their significance in California and the value of the UCM Reserve in protecting them given that many have been lost to development. Her presentation will highlight some of the animals attracted to the ponds, some easily seen but others inconspicuous.
Kolster has worked as a naturalist lecturer at the UCM Vernal Pools and Grassland Reserve for the last year and a half, offering various naturalist classes to the UCM community and the public. For the last year, she also served as the interim director of the reserve, and as of December, as the director. She has taught as an adjunct biology instructor at community colleges for more than 13 years and has extensive background in ecological field work.
Like all Yosemite Area Audubon programs, Kolster’s presentation is open and free to the public, although donations to defray program costs and to support the chapter’s local activities are welcome. Call (209) 742-5579 for more information about the program.
Yosemite Area Audubon will also offer a field trip to Millerton Lake Saturday, Feb. 11, beginning at 7:30 a.m. Contact Vern Johnson, firstname.lastname@example.org, for more information.
The mission of the National Audubon Society, the namesake of noted 19th-century naturalist and bird painter John James Audubon; its state affiliate, Audubon California; and local chapters such as the Yosemite Area Audubon Society is to conserve and restore natural ecosystems, focusing on birds, other wildlife and their habitats for the benefit of humanity and the earth’s biological diversity.