Rare S1-S4 Alliances: Vegetation Southern San Joaquin Valley [ds1021]

Vegetation polygons were manually digitized as interpreted using the National Agricultural Inventory Program's 2012 (NAIP 2012) aerial imagery at a scale of 1:2000. The minimum mapping unit (mmu) for natural vegetation is 1.0 acre, with a minimum average width of 10 meters. The mmu for agricultural and urban polygons is 10 acres. Vegetation is attributed to the Group and Alliance level of the state and national vegetation hierarchy. In some cases, polygons were attributed only to Group or Macrogroup level when the Alliance could not be determined from photointerpretation. The map classification is based on the key to vegetation types in Buck-Diaz et al. 2012. * The MapClass Schoenoplectus (acutus, californicus) is a mapping unit which includes two seperate alliances which are within two seperate groups. To retain the finest level of detail we crosswalked everything that was mapped to this mapping unit to the Schoenoplectus californicusSchoenoplectus acutus association in Schoenoplectus californicus alliance. Mapping standards are the same as are specified in Fine-Scale Riparian Vegetation Mapping of the Central Valley Flood Protection Plan Area (CDFW and GIC 2013) and are summarized here. Please refer to that document for more information. Polygons are attributed with absolute percent cover of hardwood tree, conifer tree, total tree, and shrub life forms in 1% increments. Herb cover is attributed in one of five cover classes. Cover of all of the life forms were estimated using "Birdseye Total Cover" i.e., what can be seen on the aerial photo excluding understory layers when covered by an overstory layer. Cover estimates consider the porosity of the canopy (i.e., holes in the canopies of individual trees or shrubs). Tree type alliances were mapped when trees were >5% of the polygon. If there was a change in canopy overstory density or size class within the same alliance, the polygon was segregated if it was >5 acres. If the understory layer cover changed but the alliance remained the same, the polygon was segregated if it was >10 acres. Shrub vegetation alliances were mapped when tree cover was <5%, and the shrub cover was >10%. The percent of absolute shrub cover was estimated taking into account the porosity of the shrub layer. Heterotheca oregona, Allenrolfea occidentalis, Suaeda moquinii, Atriplex lentiformis, and Frankenia salina are the exceptions to this rule and are classified as shrub types with cover as low as 2%. A total of 772 (6%) of the polygons were viewed in the field by the mappers. Due to funding limitations, accuracy of this map was not tested but is assumed to be consistent with the 88% users and 87% producers accuracy of the map of the Sacramento Valley based on the same classification and mapping standards produced by GIC. Edgematching this map to the Carrizo National Monument map will occur as funding allows. References: Buck-Diaz, J., S. Batiuk and J. Evens. 2012. Vegetation Alliances and Associations of the Great Valley Ecoregion, California. California Native Plant Society. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=64011 California Department of Fish and Wildlife (CDFW) and Geographical Information Center (GIC). 2013. Fine-Scale Riparian Vegetation Mapping of the Central Valley Flood Protection Plan Area, Final Report https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=74420 Miles, S.R., and C.B. Goudey. 1997. Ecological subregions of California. Technical Report R5-EM-TP-005. USDA Forest Service, Pacific Southwest Research Station, San Francisco, CA. Carrizo National Monument Vegetation Map: ftp://ftp.dfg.ca.gov/BDB/GIS/BIOS/Public_Datasets/800_899/ds891.zip Conservation Opportunities-San Joaquin Valley Map: ftp://ftp.dfg.ca.gov/BDB/GIS/BIOS/Public_Datasets/400_499/ds422.zip