Abstract
In California’s Central Valley, grassland and oak savannah ecosystems provide multiple economic and social benefits, ecosystem services, and vital bird habitat. There is a growing interest in protecting, restoring, and managing these ecosystems, and the Central Valley Joint Venture (CVJV) provides leadership in the formulation of conservation goals and objectives. We defined a long-term goal of protecting, restoring, and managing Central Valley grassland and oak savannah ecosystems so that they are capable of supporting genetically robust, self-sustaining, and resilient wildlife populations. To measure progress toward this goal, we selected a suite of 12 landbird focal species that primarily breed in grasslands and oak savannahs as indicators of the state of these ecosystems on the Central Valley floor (primary focus area) and in the Central Valley’s surrounding foothills (secondary focus area). Using data on current densities and habitat extent, we estimated that at least three of the focal species populations in the primary focus area and at least two of the focal species populations in the secondary focus area are currently small (<10,000 individuals) and may be vulnerable to extirpation. Furthermore, at least two species appear to have steeply declining population trends. We defined long-term (100-year) population objectives for each focal species that we expect to meet the goal of genetically robust, self-sustaining, and resilient populations. We then estimated corresponding short-term (10-year) habitat objectives of 4,183 ha of additional grassland and 3,433 ha of additional oak savannah that will be required to make progress toward the long-term objectives. We expect that habitat restoration and enhancement efforts aimed at reaching these long-term conservation objectives will result in improvements to the function of Central Valley grassland and oak savannah ecosystems.
Highlights
Grassland and oak savannah ecosystems are an important component of California’s Central Valley uplands, the open country “bathtubSAN FRANCISCO ESTUARY & WATERSHED SCIENCE ring” of low-elevation foothills and rangelands that surround the perimeter of the valley floor (Figure 1)
Because we used the focal species as indicators of the state of Central Valley grassland and oak savannah ecosystems, we evaluated the collective status of all the focal species’ populations
The vast majority (94%) of the oak savannah habitat occurs within the secondary focus area, indicating that oak savannah habitat is extremely limited in the primary focus area (Figure 1; Table 3)
Summary
Grassland and oak savannah ecosystems are an important component of California’s Central Valley uplands, the open country “bathtubSAN FRANCISCO ESTUARY & WATERSHED SCIENCE ring” of low-elevation foothills and rangelands that surround the perimeter of the valley floor (Figure 1). Rapid climate change threatens to degrade a number of ecosystem services, including forage production and carbon sequestration (Kueppers et al 2005; Shaw et al 2011; Byrd et al 2015). Given these threats, and the multiple benefits of conserving these ecosystems, there is a strong and growing interest in protecting, restoring, and managing grasslands and oak savannahs in California. For these efforts to be successful, clear goals and objectives are necessary
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