Reconstructing the conservation history of California over the last 80 years

Background/Question/Methods

Exceptionally rapid human-caused changes in climate and habitats threaten the persistence of biodiversity. Learning from conservation history can help us strategically define future conservation goals. Conservation history describes the process through which current day conservation came to place. Documenting this process entails a spatial and temporal depiction of historical conservation activities, implementation, and achievements. Using historical (1930-1940's - Wieslander Vegetation Type Maps) and current (2006-2008 - CalVeg) land cover maps, we conducted a change detection analysis to assess the amount and locations of change in the San Francisco Bay Area region.

Results/Conclusions

In the overlapping area of the historical and current land cover maps (8800km2), 85% has changed over the last 80 years. Of the historical extent, grasslands and urban areas were the land cover classes that transitioned the least, and oak woodlands and agriculture transitioned the most. The greatest transition went into urban areas (from 386km2 to 2144km2), and greatest loss from agriculture (3205 km2 to 515 km2). Using the map of Open Space areas, we linked the chronology of protection, conservation targets, with historical landmarks. Since 1850, 3723 Open Space properties have been "acquired" (2960 km2) in the overlapping area of the historical map. To date we have been able to track the acquisition dates of 1737 of these properties (2116 km2; ca. 70% area). Of those Open space areas with acquisition dates, we observe that the greatest boom of acquisition occurred after 1960, with 1575km2 after 1960 and 541km2 before 1960. This matches the funds provided by the 1955 funding for State Park acquisition, and some of the funds of the 1945 Omnibus Parks Acquisition Act (to acquire coastal areas). There was high variability on which land cover classes were protected and when. After 1960, there was a major increase in agricultural lands, grasslands and redwood forests (after an initial effort in 1920's) in Open Space properties. We expect to expand and apply this same framework to California's network of Open Space areas to further our understanding of the history of the region's protection.