This study investigates the relative distribution, health, and regeneration patterns of two major stands of sycamore alluvial woodland (SAW) in Santa Clara County, representing managed and natural settings. Using an array of ecological and geomorphic field analyses, we, along with our partners at H.T. Harvey, discuss site characteristics favorable to SAW health and regeneration, make recommendations for restoration and management, and identify next steps. Findings from this study will contribute to the acquisition, restoration, and improved management of SAW as part of the Santa Clara Valley Habitat Plan (VHP). A goal of the VHP is to identify, protect, and restore this land cover type within its reserve lands.
In California, sycamore-alluvial woodland habitat is relatively rare due to extensive habitat loss, yet provides regionally unique habitat values for nesting and roosting riparian bird species, steelhead trout and other native fishes, as well as amphibians and reptiles. If supportive physical conditions and processes can be reestablished, sycamore-alluvial woodland might be a cost-effective restoration target ecosystem, given future projections of droughts, and the ability of sycamores to thrive with limited summer water and intermittent flows. The health and regeneration of existing California sycamore stands are likely affected by a wide range of factors, including hydrologic modifications of creeks, hybridization with non-native London plane tree (Platanus × hispanica), and pathogens such as sycamore anthracnose. While recognizing that previous research as identified the biotic and abiotic factors influencing sycamore regeneration, some of the factors are still relatively poorly understood, and there is a need for site-specific management recommendations.
In an effort to better understand factors supporting SAW regeneration, this project examines four major questions:
- What are the site characteristics most favorable to health and reproduction of SAW?
- Which specific locations are recommended for acquisition, restoration or management within the VHP priority preserve areas?
- How can current management practices be modified to support SAW?
- Which active restoration strategies are likely to be successful?