The final version of the Coarse Filter Vegetation Map is a 30m grid GIS <>dataset with 61 cover types, 51 of which are natural or semi-natural land cover. More detail about the creation of the map can be found below and in Chapter 4: Coarse Filter: Vegetation of the full report. Figure 4.5 in Chapter 4 describes the species composition for each vegetation type shown on the Coarse Filter Vegetation Map.
Creating the Coarse Filter Vegetation Map
The first challenge faced by the Vegetation Focus Team was the lack of a consistent vegetation map covering the region. The team’s preferred vegetation classification system was A Manual of California Vegetation (MCV; Sawyer et al. 2009) because of the detail it provides. However, only a few areas within the Upland Habitat Goals study area are mapped using MCV, and the project’s conservation planning software, Marxan, is more effective with consistent vegetation classifications. An alternative vegetation classification system developed by the US Forest Service, CalVeg, covers almost the entire region but has some spatial inaccuracies and lacks sufficient detail for annual grasslands, shrub communities, riparian corridors, and isolated wetlands.
The Vegetation Focus Team agreed to use a modified version of CalVeg, referred to as the Upland Habitat Goals Coarse Filter Vegetation Map, which provided adequate and consistent coverage for the full study area. The Coarse Filter Vegetation Map is a composite of several data sources described below and shown on the map that follows:
Sources used to develop the Coarse Filter Vegetation Map
Two primary enhancements were made to this composite vegetation map. First, a serpentine geology layer from the USDA Natural Resources Conservation Service State Soil Geographic (STATSGO) Database was added to capture the unique vegetation types found on serpentine soils. Second, a climatic stratification was developed to differentiate the approximately one million acres identified as Annual Grasslands in CalVeg. These grasslands were separated into Cool, Moderate, Warm, and Hot Grasslands based on July maximum temperatures established by PRISM (800m-scale Parameter-elevation Regressions on Independent Slopes Model), a climate mapping system developed at Oregon State University. The figure below illustrates these temperature stratifications.
Riparian areas pose special challenges at the regional scale of the Upland Habitat Goals Project. While the Coarse Filter Vegetation Map captures the larger patches of riparian forests as mapped by CalVeg, it misses the many narrow ribbons of remnant riparian habitat. To capture these smaller riparian areas, the USGS National Hydrologic Database (NHD) was used in the fine filter process to define stream corridors; streams are included as conservation targets in the final version of the Conservation Lands Network.
The last step in the development of the Coarse Filter Vegetation Map added the Farmland Mapping and Monitoring Program (FMMP) Urban and Cultivated Agricultural data, along with rural residential areas with parcels less than 10 acres – areas collectively referred to as Converted Lands and shown in the figure below. The FMMP data were more current (2008) than similar land use types in CalVeg, and thus provided an important update. Rural residential parcels, typically found on the urban fringe, are of lower conservation suitability. Appendix B: Data and Methods, Chapter 4 describes how the Rural Residential data layer was created.
Marxan occasionally selected Converted Lands for inclusion in the Conservation Lands Network if they contained conservation targets needed to meet the 90%, 75%, or 50% goals, or if the 247-acre hexagon included 10% or more of protected lands. As noted in Chapter 3: Approach and Methodology, Converted Lands over-selected by Marxan were removed from the CLN (see Figure 3.9 in Chapter 3 of the full report).