Conservation and restoration practices require a clear expectation about how the undisturbed landscape was organized in order to be effective and successful. In the Central Valley of California, much of the at-contact landscape was converted to agriculture by settlers in the 1850s, well before the native vegetation was explicitly mapped. In the absence of a comprehensive spatial record of vegetation distribution, I have inventoried various and disparate historical data sources with which to reconstruct the potential distribution of native vegetation for the region surrounding the Cache and Putah Creek distributaries in the southwestern portion of the Sacramento Valley, in northern California. Upon investigating the historical ecology of the region I have found evidence for wetland, grassland, vernal pools, and valley oak trees in varying densities from forest to savanna, in addition to riparian forest of varying width and composition along the waterways.
In the first chapter, a suite of resources that describe the historical vegetation in different ways are introduced. Records for this region include written accounts, various maps, photographs, newspaper articles as well as early aerial photographs from the late 1930s. The process is described by which these written and pictorial descriptions are ingested into a Geographic Information System (GIS). In addition, a series of maps that spatially delimit and describe the geology, physiography, soils, topography, and hydrology of the region are presented.
The Public Land Survey data of the General Land Office is the substance of the second chapter. There are several different types of survey descriptions that are recorded and made accessible within a geographic framework. The information collected in these surveys is then used to investigate the relationships to the series of environmental variables introduced in the first chapter.
The third chapter maps the locations and showcases a subset of early drawings and lithographs that represent the agricultural development of this floodplain region. Each of these representations is classified based on the content, and geo-located, so that they may be considered along with the other resources in the domain of spatial coincidence.
In the fourth chapter, an integrative interpretation of these resources culminates in a vegetation reconstruction consisting of vegetation mosaics of woody vegetation, grassland and wetland regions. Of direct relevance to conservation and restoration planning, these results establish a potential baseline of historical vegetation distributions, which can be used to identify and prioritize conservation targets as well as identify the restoration potential in the region. Finally, in the last chapter a brief vision on conservation and restoration for this region is described.
|Advisor:||Ustin, Susan L.|
|Commitee:||Dahlke, Helen E., Hijmans, Robert J.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-A 80/11(E), Dissertation Abstracts International|
|Keywords:||Alluvial plain, Cache and Putah creeks, Historical ecology, Lithographs, Public land survey, Valley Oak (Quercus lobata)|
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