Background
In 1999, the Partnership began development of a geographic information system (GIS).  The GIS provides a scientific basis for the Conservation Framework and demonstrates how accurate spatial information and scientific principles can be used in support of developing a common conservation vision.  A GIS allows layers of spatial information to be viewed together and analyzed quantitatively, leading to a greater understanding of the resource characteristics of a given study area. The BRBNA GIS combines many layers of spatial information that pertain to three distinct areas (domains) of conservation: 1) Biodiversity, 2) Working Ranches and 3) Recreation. The results of this mapping effort allow the Partnership and its members to evaluate lands within the BRBNA and establish priorities for conservation within these three domains.

Previous GIS-based conservation mapping efforts in the region were limited in either spatial extent or data resolution, including The Nature Conservancy's (TNC) North Coast Ecoregional Plan, CalWater Planning Watersheds, and NatureServes's Project Aldo.  TNC identified sub-watershed scale conservation targets averaging 26,000-acres in size; CalWater used sub-watersheds averaging 6,000 acres, and NatureServe mapped 40-acre pixels. The GIS model developed by the Partnership incorporates a greater extent of high-resolution input data and increases analysis resolution to one-acre grid cells. Mapping at this scale provides the detail and scientific validity necessary to analyze biodiversity patterns and identify conservation priorities within ownership blocks across such a large study area.

Mapping and modeling was prepared by the UC Davis Information Center for the Environment (ICE) and Jake Mann, GIS Specialist, using Universal Model Builder (UMB), an ArcView/Spatial Analyst GIS software extension that ICE developed for the US Forest Service (see Appendix F for the full ICE 2004 final report).  UMB allows users to combine maps in a conservation priorities model, assigning different weights to different conservation values based upon the perceived relative importance of those values to the user.  Therefore, as previously noted, outcome scenarios may differ depending on priorities that have been designated.

UMB is simply a tool that can be used by the partners to make more informed decisions about conservation projects, be they land acquisitions or stewardship efforts.  It also allows the Partnership to promote more proactive conservation in view of the region as a whole.  With limited financial resources available, it is important for all conservation entities, public and private, to prioritize their efforts and get the most conservation value for their dollar.  Other factors will undoubtedly weigh into many decisions such as the mission of an organization/agency, opportunities at hand (willing sellers), funding availability, political and policy challenges, etc.  However, a strong set of priorities backed up with solid data can provide important momentum and leverage for activities on the ground.  The development of conservation priorities through the UMB establishes a scientific standard for regional efforts and a common hub around which to coordinate activities of the partners.

Mapping Method
For all three domains, the mapping method was the same. First, data layers were acquired or created. The input data layers are the scientific information that underlies the model results for each domain – biodiversity, working ranches, and recreation.  Data that were used with UMB include:

• Roads
• Perennial and seasonal streams
• Waterbodies
• Soils
• High-resolution Vegetation
• Species Occurrence
• Viewsheds
• Parcel & ownership information
• Trails and recreation workshop data

Vegetation Mapping
The vegetation mapping of BRBNA's 785,000 acres was completed using two different data sources. ICE completed high-resolution mapping (using aerial photographs with a two acre mmu and less) for approximately 478,000 acres or 61% of the BRBNA. Less-resolute CalVeg data (derived from satellite imagery) was used for the rest of the study area. The ICE mapping generally covers most of the BRBNA south of Highway 20 with the exception of the area east of Highway 29 as illustrated in Figure 5-1: ICE and CalVeg Mapping Coverage.

Domain Mapping and Data Ranking
To create the priorities for each domain – biodiversity, working ranches, and recreation – relevant data layers were selected for use from the overall catalog of GIS data. The data layers used to create the three priority maps are identified in each section below.

The appropriate set of data layers was selected to develop the priorities for biodiversity, working ranches, and recreation. For example, the biodiversity layer was created using the following data layers:

• Roads
• Streams
• Soils
• Vegetation
• CNDDB Species Occurrence (California Natural Diversity Database)

The data was either used directly or was ranked in some way for use in the domain mapping. For example, data on serpentine soil locations was used directly and assigned the highest rank of 5 in the biodiversity layer because of its importance in hosting a wide variety or rare and endemic plants. Alternatively, the data layer, roads, was converted to a map of road density based upon the kilometers of road per square kilometer. For the biodiversity modeling, areas with the lowest road density were most suitable for biodiversity due to absence of disturbance so these areas were assigned a high rank of 5. As road densities increased, rankings of 4 through 1 were assigned with 1 being areas with the highest road density. Some small roads were indicated as potential trail corridors in the recreation model, and thus were ranked "5" for input to UMB.