Working Ranch Data Layers and Priorities
Method
The working ranch suitability analysis was prepared in February 2004 specifically
for cattle grazing. The results of the mapping would likely be different if a
different species was the focus of the analysis. As discussed previously, the
model is very flexible and different data layers can be combined and prioritized
differently to answer different questions. The following GIS data layers were
used in this analysis.
Soil Type
The US Department of Agriculture Natural Resources Conservation Service
(NRCS) Soils Survey Geographic (SSURGO) database is the most detailed level
of soil mapping done by the NRCS. SSURGO data was used to identify pasture/rangelands.
Non-irrigated capability classes 6 and 7, with Class 6 soils being more suitable
for grazing, were selected as these are the soils most suitable for pasture
and rangeland. Figure 5-10: Grazing Soils (SSURGO) illustrates
the most suitable soils in green.
Grassland and Sparse Oak Woodland Communities
Grassland communities suitable
for grazing were derived from the vegetation map and are illustrated in Figure
5-11: Grasslands Suitable for Grazing. These areas are:
In addition, the vegetation map was used to identify oak woodland types without riparian associations. Areas with a canopy cover of less than 40% (or conversely, 60% or more grassland cover) were identified as most suitable for grazing and are illustrated in Figure 5-12: Sparse Oak Woodland Communities Suitable for Grazing. These communities are:
Agricultural Lands
SSURGO data on soil potential for vineyards was intersected
with the FMMP grazing layer to indicate both vineyard development potential
and/or threat of vineyards on viable rangelands. These areas are illustrated
in Figure
5-13: Agricultural Lands. This data layer received a high value indicating
that lands with vineyard development potential were important to conserve as
working ranches.
Owner Density
Low ownership density is an indicator of working ranch suitability.
The fewer the number of owners in a given area, the more suitable the land
is for large working ranches. Ownership density was derived by aggregating
parcel data by owner. From a conservation perspective, working with a single
owner to conserve and manage a large working ranch is easier than working with
multiple owners. Figure 5-14: Ownership Density illustrates
areas with the lowest owner density in dark brown and the highest owner density
(generally subdivisions) in white. It should be noted that some of the areas
indicated in dark brown are public lands and will later be excluded from this
analysis.
Visibility from BRBNA Roads and Public Lands
This map layer takes into account
the scenic preservation value of lands used for grazing. Lands that were visible
from points along selected BRBNA roads were assigned conservation values. In
addition, scenic points from the recreation data were used to calculate viewsheds
from valued vistas in the BRBNA. Land visible from the most points received
the highest values. In Figure
5-15: Visibility from BRBNA Roads and Public Lands the areas with
the darkest colors are the most visible.
Working Ranch Priorities
The primary working ranch conservation priorities indicated by the mapping
and analysis are:
Figure 5-17: Working Ranch Suitability illustrates those areas of the BRBNA that are most suitable for ranching. Some of these areas are currently in ranching operations while others may not be. This map was created using the data and information described above with a variety of values and weights assigned to each data layer. Areas with low suitability for ranching were removed (Figure 5-16a: Chaparral Exclusion Layer). The map includes all contiguous areas greater than 200 acres (Figure 5-16b: Contiguous Ranch Lands of 200 or More Acres). Figure 5-17 indicates that the areas most suitable for ranching are, from north to south: Bear Valley, Cortina Ridge, the eastern slope of the Blue Ridge in Yolo County and the east side of Lake Berryessa. In general, when considering a working landscape conservation acquisition, other lands to protect and conserve are:
Recreation and biodiversity conservation decisions are largely driven by what is on the ground Ð sensitive habitat, scenic vistas, creeks and water bodies, etc. For working ranches, conservation decisions also have a significant economic component. If a ranch is not economically viable, it may cease to function as a working ranch and succumb to development pressures. For this reason, it is also important to consider criteria for maintaining economic viability. There is a threshold size below which ranching in the BRBNA is not profitable. In addition, ranching that is positively supported by the factors listed below is more likely to be profitable. Moreover, economically healthy ranching operations are better positioned to implement resource-friendly stewardship practices.
Factors that influence the economics of ranching: