Authors: Maria Santos1, James H. Thorne2, Zephyr Frank1, and Jon Christensen3
1 Spatial History Project; 2 Information Center for the Environment, University of California Davis; 3 The Bill Lane Center for the American West, Stanford University
Abstract: The landscape of the nine-county Bay Area has experienced great land cover conversion over the last two centuries, and only since the beginning of the last century has conservation of land been an option. Conservation in the Bay Area is probably one of the best documented conservation histories. Understanding the historical pathway through which conservation came into being (both when and what) can provide an added perspective to inform future conservation implementation strategies and challenges in the region. Using historical (1930-1940's) and current (2006-2008) land cover maps, we conducted a change detection analysis to assess what and how much has the land cover in the region changed. Using the map of Open Space areas, we linked the chronology of protection, conservation targets, with historical land marks. 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 (both tilled and working landscapes, 3205 km2 to 515 km2). Since 1850, 3723 open space properties have been "acquired" (2960 km2). To date we have been able to track the acquisition dates of 1009 of these properties (1450 km2; ca. 50% area). Of those open space areas with acquisition dates, we observe that the greatest boom of acquisition occurred after 1960, with 1064km2 after 1960 and 387km2 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 got protected when. After 1960 there was a major increase in agricultural, grasslands and redwood (after an initial effort in 1920's) in open space properties. Since, this is an ongoing project, we expect that the completion of the acquisition dates will further our understanding of the history of the region's protected network.