The Conservation Lands Network (CLN) is the recommended configuration of interconnected habitats for preserving biodiversity in the Bay Area. In designing the CLN, a myriad of factors had to be considered with less than complete information. For this reason, the conservation planning software, Marxan, was selected to assist with the reserve design. Marxan, widely used by conservation planners, enables the user to include the conservation targets (coarse and fine filter), goals for those targets, land use, proximity to existing protected lands, and the conservation suitability (ecological integrity) of the landscape in arriving at a solution. Because the project team chose to build from the existing protected lands, the modified Bay Area Protected Areas Database (BPAD) was “locked in” forcing Marxan to give preference to adjacent areas.
Much more detail on the methodology and Marxan can be found in Chapter 3 and Chapter 4 of the full report.
Once Marxan identified a draft Conservation Lands Network, it was reviewed for connectivity and coverage of the coarse and fine filter targets by the focus teams. Expert opinion of the focus team members was used to make final adjustments to the CLN.
Marxan was programmed to complete one million iterations each of the 20 times it was run. Marxan creates a “near optimal” conservation reserve network based on these runs and iterations, generating statistics on the number of times a planning unit is selected for inclusion in the Conservation Lands Network. This latter measure is an indication of the “irreplaceability” of a site to meet the conservation goals. Sites selected 90-100% of the time, for example, could be considered required to meet conservation goals.
Marxan allows the user to select how the results are displayed. The project team selected the summed solutions option, which uses the number of times each hexagon was chosen (out of the total number of times the software was run) to determine which hexagons to include in the CLN.
The following categories were chosen for inclusion in the Conservation Lands Network:
Areas for Further Consideration
The Conservation Lands Network generated by Marxan largely captured a coherent and representative network across the landscape units. However, there were a number of areas where the Conservation Lands Network did not capture important biodiversity targets, develop a viable local configuration, or provide local (within landscape unit) connectivity. In these cases, planning units (247-acre hexagons) were identified as “Areas for Further Consideration” using the expert opinion of Stuart Weiss, Ph.D., the project Science Advisor, in conjunction with Ryan Branciforte, Director of Conservation Planning for the Council.
These areas, highlighted in light blue on the CLN map, illustrate where the CLN may have fallen short for various reasons. Areas for Further Consideration were not added to the CLN because data is insufficient to determine which are most important. Decisions regarding specific lands to add to the Conservation Lands Network will require better biological data. A few key points about the Areas for Further Consideration should be noted:
Each Area for Further Consideration, the reason for its inclusion, and the number of planning units it encompasses is described below. The numbers correspond to those in Areas for Further Consideration map. Note that some of the Areas for Further Consideration are composed of several discontinuous areas.
1. Baylands Boundary. All planning units that are not completely Urban or Cultivated Agriculture that include the Baylands boundary are important to cope with sea level rise and provide possible uplands-baylands connections. All of these are in the North Bay, with the greatest opportunities in the Montezuma Hills and Solano Delta Landscape Units. Small slivers around the Petaluma River were also included. 38 Planning Units.
2. Marin Baylands Connection. These planning units are not on the immediate Bayshore, and provide local connectivity from inland areas to the Baylands within the Marin Coast Range Landscape Unit. 3 Planning Units.
3. Southern Sonoma Mountain. These planning units provide local connectivity within the Sonoma Mountain landscape unit, including across Highway 116, and include many ponds that may support California red-legged frog. 32 Planning Units.
4. Bodega Bay Connection. These planning units connect the Coastal Grasslands landscape unit to the Sonoma Coast Range landscape unit via the shortest path near the coast, a key regional linkage. 10 Planning Units.
5. Coho Core Areas – Northern Spotted Owl. These planning units include a combination of Coho Core Areas and known Northern Spotted Owl territories. 14 Planning Units.
6. Coho Core Areas: These planning units complete Coho Core Area watersheds in the Sonoma Coast Range and Santa Cruz Mountains landscape units that did not fall within the Conservation Lands Network. 60 Planning Units.
7. Northern Mayacamas - Sonoma Coast Range Connectivity. These planning units form an important regional connection north of Cloverdale across Highway 101 and the Russian River. 15 Planning Units
8. Coho Phase I Expansion Areas – Northern and Southern Mayacamas. The planning units provide regional connectivity between the Northern and Southern Mayacamas landscape units, and fall within Coho Phase 1 Expansion Area watersheds. 14 Planning Units.
9. Coho Phase I Expansion Areas – Northern Southern Mayacamas. These planning units provide connectivity in the northern part of the Southern Mayacamas landscape unit, and fall within Coho Phase I Expansion Areas. 15 Planning Units.
10. Southern Mayacamas Connectivity. To offer local connectivity within the Southern Mayacamas landscape unit, and include important Priority 1 steelhead watersheds. 32 Planning Units.
11. Vaca Mountains West Connectivity. These planning units provide internal connectivity with the Landscape Unit. 4 Planning Units
12. Berryessa – Vaca Mountains East-West Connectivity. To provide east - west connectivity between the Blue Ridge Berryessa and Vaca Mountains West landscape units. 9 Planning Units.
13. Berryessa South Shore Connectivity. To provide a wider east-west linkage just south of Lake Berryessa. 4 Planning Units.
14. Blue Ridge Berryessa Connectivity. These planning units provide local connectivity within the Blue Ridge Berryessa landscape Unit. 21 Planning Units.
15. Vaca Mountains South-American Canyon. These planning units provide a regional connection between the Vaca Mountains West and American Canyon landscape units across Highway 12. 21 Planning Units.
16. American Canyon - Sky Valley. These areas include good grassland habitat that support Callippe silverspot butterflies, and the ponds within the grasslands support California red-legged frogs and western pond turtles. While the northern section of American Canyon falls within the existing protected lands and the Conservation Lands Network, the southern section is under-represented. 19 Planning Units.
17. Solano Connection. These planning units form an east - west connection across the Highway 80 corridor including Lagoon Valley, and are the one opportunity to connect the Solano Delta and Montezuma Hills landscape units to the rest of the region. 15 Planning Units.
18. Diablo Northwest – Concord. These planning units extend northwest from Mt. Diablo and include the proposed open space within the Concord Naval Weapons Station, as well as many known occurrences of California red-legged frog and California tiger salamander in a complex of ponds. 30 Planning Units.
19. Diablo North East -West Connection. These planning units provide the shortest distance east-west connectivity in the northern part of the Mt. Diablo Landscape Unit. 8 Planning Units.
20. Tassajara Hills. These planning units span the grasslands and ponds of the Tassajara Hills, to afford local connectivity and habitat within this important grassland area for species such as the burrowing owl, badger, and numerous ponds for California red-legged frog, California tiger salamander, and Western pond Turtle. 559 Planning Units.
21. Middle East Bay Hills Connectivity. These planning units provide connectivity within the Middle East Bay Hills landscape unit in both a north-south and east-west direction. 31 Planning Units.
22. South East Bay Hills Connectivity. The selected planning units afford local connectivity within the South East Bay Hills landscape unit, and potential connections to the few crossings of Highway 580 to the Middle East Bay Hills landscape unit. 12 Planning Units.
23. Altamont Underpass Connectivity. A connection needs to be completed between the Mt. Diablo and Mt. Hamilton Ranges just east of Livermore. Potential connections can be made by two underpasses at a seasonal stream and railroad. 5 Planning Units.
24. Northern Mt. Hamilton Connectivity. These planning units provide important local and regional connectivity from Altamont Pass south and west into the Mt. Hamilton Range, and include many ponds that likely support California red-legged frog and California tiger salamander. They supplement the connectivity provided by wind farms for many terrestrial species in this crucial linkage area. 36 Planning Units.
25. Vallecitos. These planning units support known populations of California red-legged frog, California tiger salamander, Western pond turtle, and Callippe Silverspot butterfly. 24 Planning Units.
26. Shingle Valley Tiger Salamander. These planning units support California tiger salamander and California red-legged frog in a series of ponds, and give connections between the serpentine grasslands of Coyote Ridge and the interior of the Mt. Hamilton Range. The oak woodlands and grasslands are Tule elk range. 8 Planning Units.
27. Tulare Hill Serpentine Grassland. A section of serpentine grassland on Tulare Hill was not recorded as currently protected, and forms a key part of a potential corridor across Coyote Valley from the Santa Cruz Mountains to the Mt. Hamilton Range. 1 Planning Unit.
30. Chittenden Connection. The southernmost parts of the Santa Cruz Mountains provide key regional connections to San Benito and Monterey Counties across the Pajaro River at Chittenden Gap, one of the few regional connections to the Santa Cruz Mountains. 35 Planning Units.
31. Pescadero - Big Basin Connectivity. These planning units provide direct connectivity between the Pescadero Creek watershed and Big Basin State Park in Santa Cruz County. 5 Planning Units.
32. Pescadero Creek. Portions of Pescadero Creek watershed for local connectivity to coast and points south. 5 Planning Units.
33. Stanford Foothills. These planning units fill in the foothills west of Stanford University, and are a mix of grassland and oak woodlands. 4 Planning Units.
34. San Mateo Coast North - South Connectivity. These planning units provide a series of north-south linkages along the San Mateo Coast. 12 Planning Units.