Difference between revisions of "Wildlife Connectivity in California's Central Coast Region"

Revision as of 16:20, 5 April 2020

Background

Wildlife connectivity refers to the ability of wildlife to move between different habitat patches in a landscape. Landscapes become fragmented when natural land is converted to agriculture or human development, potentially isolating wildlife populations in remaining habitat patches if connectivity is not maintained. Artificial barriers such as roads or fences can also prevent wildlife from safely moving through the landscape.

Connectivity serves a number of purposes for wildlife. Individuals may need to travel between patches to establish breeding territories or find suitable food and shelter. Isolated habitat patches may not be large enough to support viable populations of certain species, potentially leading to local extinction. Isolated populations may also experience higher rates of inbreeding, leading to a lack of genetic diversity and threatening the long-term survival of the population. ^[1] A lack of connectivity may also diminish the capability of wildlife to provide ecosystem services such as pollination.

Connectivity between habitat patches can be maintained through wildlife corridors, as well as through highway overpasses and underpasses.

Connectivity on the Central Coast

Geography

California’s Central Coast is a mixture of rugged upland habitat interspersed with fertile valleys that have mostly been converted to agriculture. Remaining habitat along the central coast includes grasslands, oak and conifer woodlands, and chaparral and coastal scrub, with more arid habitat found farther inland. Redwoods can be found in the Big Sur region and in the Santa Cruz mountains.

There are a few significant riparian corridors in the region, including the Salinas, Pajaro, and San Lorenzo rivers. Riparian corridors may function as linkages between fragmented habitat patches, promoting wildlife movement through areas of high human disturbance. ^[2]

Connectivity Studies

A number of studies have been conducted on connectivity priorities in the Central Coast region.

• Thorne et al. 2006: This study evaluated core habitat and connectivity needs for mountains lions and examined the efficacy of using mountain lions as an umbrella species to plan a connected habitat network. ^[3]

• California Essential Habitat Connectivity Project: The California Department of Transportation (CalTrans) and the California Department of Fish and Wildlife (CDFW), in collaboration with over 60 organizations, funded a study in 2010 for the statewide assessment of “essential” areas of wildlife connectivity. ^[4]

• Huber et al. 2010: This study examined potential ecological conservation networks at different spatial scales in the eastern Central Coast region and the Central Valley. ^[5]

• Bay Area Critical Linkages: The Science and Collaboration for Connected Wildlands (SC Wildlands) worked to identify 14 landscape-level habitat corridors that would preserve wildlife connectivity in the Central Coast region ^[6].

These studies show that connectivity between suitable habitat patches is often impeded in the region's valleys, which have been primarily converted to agriculture and separate remaining natural habitats found in upland areas. Connectivity in low-lying areas is further threatened by growing urbanization, as well as the 38 state and federal highways that cross through the region.

These studies also reveal some of the challenges in establishing connectivity priorities. Due to varying methodologies, including differences in the model organisms studied and the metrics used to quantify fragmentation and connectivity, there were few agreements between studies on areas where connectivity should be emphasized.

Notable Species

Recent and Current Projects

Regional Wildlife Corridor and Habitat Connectivity Plan

A 2014 study from CalTrans and the University of California, Davis found that roadwork was slated for many critical areas of connectivity along the Central Coast. ^[7] The projects, which included widening existing highways and adding median barriers, were expected to increase wildlife/vehicle collision rates and reduce dispersal capabilities of individuals that could not cross median barriers. CalTrans cited that connectivity was likely already impacted by the roads in these areas, and that additional construction could also allow them to retrofit highways to promote connectivity. Proposed techniques included widening culverts underneath highways and using wildlife fencing to direct individuals to areas of safe passage.

The Pajaro Connectivity Project

The Nature Conservancy launched a project in 2012 to conserve and restore land in the upper Pajaro River floodplain, in part to enhance wildlife connectivity between the Santa Cruz, Diablo, and Gabilan mountain ranges ^[8]. The project included river corridor restoration on a section of the Pajaro River on the Gonzales Farm, in which more than 1,200 native plants were installed to provide wildlife habitat and facilitate migration and dispersal. Pathways for Wildlife, Sempervirens Fund, Peninsula Open Space Trust (POST), Save the Redwoods, and the Land Trust of Santa Cruz County were among the collaborators on this project.

The Highway 17 Wildlife Habitat Connectivity Project

References

1. ↑ Center for Biological Diversity
2. ↑ A Riparian Conservation Network for Ecological Resistance
3. ↑ A Conservation Design for the Central Coast of California and the Evaluation of Mountain Lion as an Umbrella Species
4. ↑ California Essential Habitat Connectivity Project
5. ↑ Spatial scale effects on conservation network design: Trade-offs and omissions in regional versus local scale planning
6. ↑ SC Wildlands
7. ↑ Regional Wildlife Corridor and Habitat Connectivity Plan
8. ↑ Pajaro Compass

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