For women’s history month this year, San Diego Canyonlands wanted to highlight an ecologist whose work still influences us today even though her first findings were published in the 1930’s. Not just any Ecologist but the first professional female ecologist in California, Edith A. Purer. An advocate for protecting green spaces and one of the first to identify and study vernal pools, an endangered type of ecosystem home to rare plants and wildlife.
What’s a vernal pool? These systems are found atop a flat mesa or in some chamise chaparral habitat strands. They are basins that can be six inches deep and can stretch from the size of a car tire to the length of a football field.
Edith would spend her summers and off seasons, when she was not teaching at Hoover High School, painting California landscapes and studying and reporting on these small ecosystems that people would step over all the time. The vernal pools that Purer was studying and wrote of in her papers are now deep under concrete and footsteps as the mesas that vernal pools like to be on are prime areas for housing and other developments. San Diego State University for example sits atop what used to be a robust network of vernal pools.
While some vernal pools are surviving and can still be visited today, barred with protection there is nowhere near the same amount of access that Edith had in the past. Going back and reading her work, we may be able to find the best ways to help these few remaining vernal pools survive. Inside Edith’s findings may lie answers to questions we have yet to ask, and we owe a lot to Edith for looking beneath the surface and seeing something that was more than what it seemed.
Written by Edith; conclusion summary “ECOLOGICAL STUDY OF VERNAL POOLS, SAN DIEGO COUNTY”
Vernal pools on mesas in various portions of San Diego County are abundant on the Lindavista mesa in the foggy-desert belt, with scant seasonal winter rains. With exposure to full sun, the daily and seasonal fluctuations in the temperature of the water are high as the pools are small and shallow. Within a few months' period the pool bottoms present a rapid change from hydric to extreme xeric conditions.
The flora of the pools is distinct from that of the surrounding areas. No trees or shrubs (except one decument one) are present; there are few perennials; annuals are most numerous. The plants are mostly fragile and delicate, less than fifteen centimeters in height.
The seasonal aspect is very noticeable. At first Callitriche and green algae are abundant, then Juncus and Eleocharis become conspicuous along with Pilularia and Isoetes which grow in mud or somewhat submerged. Then Downingia, Plagiobothrys and Psilocarplus appear, then Pogogyne followed by Eryngium growing in the caked dry soil.
List quadrat studies show very dense populations in favorable portions of a pool as low as fifty plants per square meter in other portions. Variation depends principally on the amount of water present, on whether the area has been denuded or not, and on the types of plants present. Permanent quadrats show great differences in yearly appearance due to amounts of precipitation and also to grazing.
Zonation is not noticeable. Perennials are present in the deeper portions, while annuals are usually found where it is shallower. Along the margins may be found invaders from the surrounding mesa. Callitriche and green algae frequently cover the surface of the water. Liverworts are abundant on wet soil.
Sources:
https://www.californiachaparral.org/__static/2db737e4e238c0756b4be38b0633ce65/purer-vp.pdf?dl=1
https://www.californiachaparral.org/chaparral/vernal-pools/
https://en.wikipedia.org/wiki/Edith_Abigail_Purer
https://www.askart.com/artist/Edith_Abigail_Purer/11006403/Edith_Abigail_Purer.aspx
https://web.archive.org/web/20190908035908/http://www.naturespeace.org/pureranthology.htm