Upon inspection of the assembled Yolo County vegetation/landcover GIS layer it was determined that significant portions of the County lacked spatial and floristic detail that is necessary for use by regional conservation planning efforts. Focusing on these problem areas, airphoto interpretation in conjunction with field validation were used to add mapping units (polygons) and enhance the floristic detail (change the vegtation/land use category to a more detailed one). Upon completing these tasks, the GIS vegetation/landcover layer was reviewed by independent scientific advisors for its completeness and adequacy for use in regional conservation planning. The review recommended that additional work be undertaken to supplement spatial and floristic detail.
In the second phase, additional data sources were obtained, evaluated, and added to the vegetation/landcover layer that was compiled thus far. As with the first original data sources, these data had differing mapping and categorical detail. Portions of these data sources (a selected set of polygons) were extracted from these data sources and added into the compiled Yolo County vegetation/landcover GIS layer. This was done to capture the greatest spatial or categorical detail, with the intended use for regional conservation planning in mind. Additionally, airphoto interpretation was used with the focus on mapping additional riparian areas, as recommended by the independent science advisors. This was performed systematically across the entire County. Following this, with the purpose to correctly classify these newly added riparian areas, and to review the polygons and classifications that came from the new data sources obtained in phase two, the data was reviewed and edited using field verification and airphoto interpretation.
During the spring and summer 2007 Jim Estep conducted systematic surveys and mapped all of the agricultural lands in the valley floor of Yolo County as a part of the Swainson's Hawk research project being conducted for the Yolo Natural Heritage Program (Estep 2008). During November 2007 this agriculture mapping was used to update the agriculture categories in the Yolo Natural Heritage Program Land Cover/Vegetation Data Layer described above. The DWR detailed agriculture classification was also incorporated and updated as a part of this process and the Estep data was cross-walked to this DWR detailed classification. Specific crop types in the detailed agricultural information (e.g., tomatoes or alfalfa specifically, but not all truck and berry or pasture generally) was required for some species models that use specific agriculture types as a part of their life cycle. The resulting update to the Land Cover/Vegetation Data Layer provides a current map of land cover, crop types, and natural habitats across the entire County.
In the spring of 2008 the 2004 orthophoto was used to update the vegetation layer. The orthophoto was reviewed in detail to identify any additional ponds that were not captured by the previous mapping efforts. At the same time, areas that were seen as developed on the orthophoto were updated.
It is very important to note that although the Yolo County vegetation/landcover layer is a seamless layer, the mapping is a product from data sources that had different mapping methods, these being driven by their unique purpose of conducting the mapping. While this effort to compile the Yolo County vegetation/landcover GIS layer worked to standardize this through classification crosswalks and supplemental mapping, some areas will still appear inconsistent compared to other areas. Additionally, the mapping precision (how precicely placed boundaries are) will vary considerably. That being the case, all spatial or categorical assessments of this GIS layer should be conducted with an understanding of the intended purpose of this data: conservation planning at a Regional level.
UC Davis (UCD), California Department of Fish and Game (CDFG), and Aerial Information Systems (AIS) jointly mapped habitats in Napa County that extended into the Blue Ridge and Little Blue Ridge region of Yolo County. That map was created using the Manual of California Vegetation (MCV) classification system, aerial photo interpretation, and limited field verification. Habitats that could be formally assigned to a defined type in the MCV classification system were classified at the alliance level (floristic-based), although a few associations comprising several vegetation types were also included. All grass types, many shrub types, and low-density stands of foothill pine were not identifiable in the aerial photos. Therefore, these vegetation types were aggregated into a "super alliance." Vegetation types that could not be formally assigned because the type had not been formally defined, or because the type could not be distinguished in the aerial photographs, were assigned a provisional classification consistent with MCV and were identified as Not Formally Defined (NFD).
The NCVM effort used limited field reconnaissance to collect data on dominant species composition and environmental features. These data were used to create a photo-interpretation key that was used to extrapolate the classification to other areas with similar photographic signatures. The photo interpreters then digitized and labeled each polygon on U. S. Geological Service (USGS) digital orthophotos flown in 1993. The general minimum mapping unit was 2.5 acres, although units as small as 0.63 acre were delineated around important features such as agricultural ponds. Photo interpreters used the polygons with known vegetation and extended the labeling process to nearby polygons with similar photo interpretation characteristics. Incorrect labeling of polygons was noted and corrected in similar polygons using an automated process. The verification process also was used to refine the species-environment relationship models, which permitted areas within unvisited polygons to be classified as super associations.
California Department of Water Resources Land Use Map DWR periodically (generally every 5 to 10 years) surveys the agricultural sections of counties to quantify agricultural land use by crop type, crop rotation group, water supply, urban development, and wetlands. The latest survey describing the Capay Valley, alluvial plains of Yolo County, and Colusa and Yolo Basins was conducted by DWR in 1997. DWR's crop classifications are classified as nine types of structurally similar crop types or groups and three land use designations.
Yolo County Draft HCP (EIP Associates) The classification effort and other data compiled for the initial HCP (EIP 2001) provided useful information on select habitats in the eastern and valley portions of the YNHP area. EIP Associates prepared GIS-based habitat maps of the 2001 draft HCP area by evaluating ecological data, including the physical and biological descriptions of the locations where proposed covered species were known to occur (EIP 2001). The initial HCP effort identified and mapped the following primary habitat types: riparian, wetland, woodland, grassland, and agricultural. In addition, 16 specific habitat subtypes were classified based on habitat associations of the species proposed for coverage under that HCP.
A description of the new data sources that were combined with the Phase 1 data to form the vegetation layer for the YNHP are described below.
Bay/Delta Vegetation Mapping This dataset was created by Aerial Information Systems, Inc. for the CDFG using the CDFG's vegetation classification and mapping program in order to assess existing vegetation and land use conditions in the Delta region. Vegetation was mapped for the approximately 725,000 acres constituting the Legal Delta portion of the Sacramento and San Joaquin River Delta area. The map classification is based on field data collected during the summer and fall of 2005. Vegetation was mapped from the sub-alliance to super-alliance level using the National Vegetation Classification Standard (<http://biology.usgs.gov/npsveg/nvcs.html>). Maps were at 1:12,000 scale, vegetation was mapped at a 2 acre minimum mapping unit, and critical vegetation types such as wetlands were mapped at a 1 acre minimum mapping unit. Features that were very distinct or important were mapped below the minimum mapping unit.
Sacramento River and Major Tributaries Riparian Zone Mapping This mapping effort was completed by Chico State University in order to inventory and map riparian lands along the Sacramento River and its major tributaries. The study area was confined to streams in the Sacramento Valley, and mapping ended in the foothill canyons on both sides of the valley. The Sacramento River mainstem was mapped in 1996, Cache Creek in 1998, and from Putah Creek in 1998. All mapping areas were at the 1:12,000 mapping scale. The Chico State mapping effort identified, mapped, and used the following vegetation classification types: Blackberry Scrub Great Valley Cottonwood Riparian Forest Disturbed Disturbed Riparian Eucalyptus Gravel And Sand Bars Giant Reed Herbland Cover Valley Freshwater Marsh Great Valley Mixed Riparian Forest Non-Riparian Open Water Great Valley Riparian Scrub Tamarisk Valley Oak
Jones and Stokes Riparian Zone Mapping Jones and Stokes, Associates completed field level riparian mapping for a significant portion of the valley bottoms and lower slopes of Yolo County during the winter 1989 and spring 1990 for the Yolo County Community Development Agency. The final product was a set of hard copy maps (no digital data layers were created). The hard copy maps were obtained by the consultant team, reviewed, and compared with the 2004 digital orthophotos. New polygons were digitized on the 2004 aerial photos to correspond to the hard copy mapped polygons and the vegetation classification assigned on the hard copy maps was correlated with these newly digitized polygons. The Jones and Stokes mapping effort identified, mapped, and used the following vegetation classification types: Valley Oak Cottonwood Forest Mixed Riparian Willow Scrub Non-woody Freshwater Marsh Perennial Moist Meadow Ruderal Wetlands Gravel Wash Alkali Sink Vernal Pools Mudflats Seasonally Vegetated Wetlands Lakes Ponds Tidal Sloughs Streams and Creeks Rice Paddies Flood Control Basin Other
Yolo MSCP The first phase of developing the Yolo County Regional Vegetation dataset was to determine the data sources that had the greatest spatial and floristic detail available. After making this determination and compiling them into one dataset TAIC and HT Harvey added spatial and categorical detail in areas that warranted it given the intended use for the Yolo County MSCP. This review process involved spatial changes and attribute editing where necessary.
Associates, Technology, Unpublished Material, YoloCounty_RegionalVegetation_July08.
This is a Vector data set. It contains the following vector data types (SDTS terminology):
The map projection used is Lambert Conformal Conic.
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest 0.000000
Ordinates (y-coordinates) are specified to the nearest 0.000000
Planar coordinates are specified in survey feet
The horizontal datum used is North American Datum of
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257222.
Sequential unique whole numbers that are automatically generated.
Coordinates defining the features.
Positive real numbers that are automatically generated.
(858) 300-2346 (voice)
The land cover map shows the distribution of natural habitats, agricultural lands, and developed areas. Understanding the distribution of these land cover types is crucial to the development of the conservation plan for the Yolo Natural Heritage Program (YNHP).
This vegetation dataset is intended for regional planning purposes. It is not intended for site specific planning. Agricultural data has been included in this dataset to assist in the decision making process. The agricultural use depicted in the dataset may vary from current ground conditions due to the dynamic nature of agriculture. Agriculture use may change from year to year and season to season; therefore, the agricultural use depicted in this dataset shows the condition at the time of mapping.
Data sources used in this process:
Data sources used in this process:
Data sources used in this process:
Data sources used in this process:
It is very important to note that although the Yolo County vegetation/landcover layer is a seamless layer, the mapping is a product from data sources that had different mapping methods, these being driven by their unique purpose of conducting the mapping. While this effort to compile the Yolo County vegetation/landcover GIS layer worked to standardize this through classificaiton crosswalks and supplemental mapping, some areas will still appear inconsistent compared to other areas. Additionally, the mapping precision (how precicely placed boundaries are) will vary considerably. That being the case, all spatial or categorical assessments of this GIS layer should be conducted with an understanding of the intended purpose of this data: conservation planning at a Regional level.
|Data format:||Size: 43.073|
The Yolo County Regional Vegetation dataset can be downloaded at <http://www.yoloconservationplan.org/maps-and-documents.html>
(858) 300-2346 (voice)