This research project is a the center of Jon Christensen's dissertation in progress.
A re-examination of the sources used to construct the dominant historical narrative of the sweeping transformation of California's grasslands by overgrazing, invasive annual grasses, and drought in the 19th century reveals spatial and temporal contradictions and complications. The dominant narrative, constructed largely by ecologists and geologists, has argued that the only spaces where native plant communities could survive were limited areas of nutrient poor, chemically harsh soils called serpentine. These relict spaces were conceived as areas where succession had stopped. And in order to preserve California's native grasslands it was argued that these areas had to be protected from disturbance such as grazing and fire.
A new spatial and temporal analysis using a newly digitized database of records from a consortium of 16 academic herbaria in California, along with additional historical observations from the 19th century and early 20th century, suggests the persistence of a more heterogeneous plant community across a wider space over a longer period of time. This analysis focuses on a threatened butterfly, Euphydryas editha editha or the Bay checkerspot, which is currently only found on serpentine soils, and the plants upon which it depends.
The dominant historical narrative of the transformation of California's grasslands has been used to explain the butterfly's demise and shape conservation strategies. It has been argued that the transformation of the grasslands left the butterfly stranded with its host and nectar plants on serpentine soils, and as those areas have been developed or fragmented in the late 20th century, the vulnerable butterfly has been driven toward extinction. This analysis suggests that efforts to protect serpentine soils and plants from disturbance likely contributed to the butterfly's demise, and that conservation efforts now underway should consider the possibilities for recovering species across a broader, more heterogeneous and dynamic landscape.
We are currently investigating a comparative spatial environmental history of 64 Bay checkerspot populations around the Bay Area to test these hypotheses.
This work is part of an interdisciplinary research project studying the feasibility of reintroducing the Bay checkerspot to Jasper Ridge Biological Preserve on the Stanford campus. That research is supported by the Woods Institute for the Environment.
This work is also part of a larger project and a set of collaborations exploring the creation of an Interactive Digital Environmental History of California.