Vegetation - Great Valley Compilation [ds3231]

Geodatabase feature class containing a map tile of vegetation within the Great Valley Ecoregion. The vegetation tile combines these datasets: Great Valley Ecoregion [ds2632], Central Valley Flood Protection Planning Area Update - 2016 [ds2890], Delta Vegetation and Land Use Update - 2016 [ds2855], Suisun Marsh 2024 [ds3221]. In areas where these datasets overlapped an erase tool was used to ensure the most up to date dataset is displayed. Great Valley Ecoregion [ds2632] The Great Valley Ecoregion vegetation polygons were manually digitized as interpreted using the National Agricultural Inventory Program's (NAIP) 2009 (Central Valley Riparian and Sacramento Valley map), 2012 (Southern San Joaquin Valley map) and 2014 (balance of San Joaquin Valley) 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 Central Valley and Sacramento Valley maps were assessed for Accuracy with an average users’ accuracy of 90.2% and users’ accuracy of 89%. The San Joaquin Valley portion of the map was field verified by the mappers but was not otherwise assessed for accuracy (see Supplemental Information below for details). Suisun Marsh 2024 [ds3221] To create the 2024 Suisun Marsh vegetation map, vegetation was interpreted from a mosaic of the true color imagery that was flown in June 2024. Polygons were delineated using heads-up digitizing (i.e., a photo interpreter manually drew polygons around each stand of vegetation) in Esri's ArcGIS Pro 3.4.3, and polygon attributes were recorded within a file geodatabase. All attributes were interpreted using the Suisun Marsh 2024 imagery as the base imagery. The photo interpreters obtained information primarily from the 2021 map and 2024 reconnaissance points as reference data, which were used during mapping to determine vegetative signatures and the appropriate mapping type for each polygon. Several other imagery sources were used as ancillary data, including 2024 NAIP, 2024 NAIP Color Infrared, all imagery available through Google Earth (including street view), and the 2021 NAIP imagery. Minimum mapping unit (MMU): Typically, the minimum mapping size is 0.25 acres. However, the photo interpreters use their best judgment to determine if a stand below 0.25 acre should be separately delineated. For example, a smaller polygon would be appropriate for any new visible occurrence of a non-native species of concern, such as Phragmites australis, Arundo donax, Carpobrotus edulis, Eucalyptus spp., and Lepidium latifolium. Minimum mapping width: There are many long and narrow polygons within the Suisun Marsh study area, most of which are roads, ditches, levees, and sloughs. The minimum mapping width is typically 10 feet; however, if small sections of a stand fell below the minimum width, the polygon was not split. Central Valley Flood Protection Planning Area Update - 2016 [ds2890] The Department of Water Resources hired the GIC in early 2010 to complete a riparian vegetation map of the Central Valley Flood Protection Plan’s (CVFPP) footprint. The total acreage of the CVFPP footprint is approximately 2,645,600 acres and spans portions of the following 22 counties: Amador, Butte, Calaveras, Colusa, Fresno, Glenn, Kings, Madera, Mariposa, Merced, Placer, Sacramento, San Joaquin, Shasta, Stanislaus, Sutter, Tehama, Tulare, Tuolumne, Yolo, and Yuba. The Central Valley Flood Protection Plan Area was remapped using 2016 National Agricultural Inventory Program aerial imagery. Change detection was performed for the Central Valley Flood Protection Plan area, comparing the years 2009 to 2016, totaling 2,645,999 acres. Each map was clipped to the designated CVFPP area boundary and then each mapping unit was analyzed for change in acreages between the imagery years. The results of this analysis can be found in Table 4. Riparian acres totaled 281,033 in 2009 and 303,823 in 2016, showing an increase of 22,790 acres (8%). Non-riparian acres were 291,582 in 2009 and 264,568 in 2016, showing a decrease of 27,013 acres (9%). Agriculture covered 1,753,706 acres in 2009 and 1,757,906 acres in 2016, showing an increase of 4,200 acres (<1%). Urban areas covered 241,002 acres in 2009 and 244,155 acres in 2016, showing an increase of 3,153 acres (1%). Delta Vegetation and Land Use Update - 2016 [ds2855] Under contract to the California Department of Fish and Wildlife (CDFW) and the Bay-Delta Region for use in conjunction with the Delta Regional Ecosystem Restoration Implementation Plan, CDFW created a fine-scale vegetation map of portions of the Sacramento-San Joaquin River Delta. The mapping study area, consists of approximately 725,600 acres, of Alameda, Contra Costa, Solano, Sacramento, San Joaquin, and Yolo counties. The minimum mapping unit (MMU) is 2 acres for land use and vegetation; exceptions made for isolated land use, water, and critical vegetation types which were mapped to a 1-acre MMU. The floristic classification follows protocols compliant with the Federal Geographic Data Committee (FGDC) and National Vegetation Classification Standards (NVCS). More information can be found in the projects reports, which are bundled with the vegetation tile published for BIOS here: https://filelib.wildlife.ca.gov/Public/BDB/GIS/BIOS/Public_Datasets/3200_3299/ds3231.zip