California’s Oak Habitat for Endangered, Threatened, and Candidate Species

Angela Moskow

Published May 2023 in International Oaks No. 34: 165–180

Abstract

California Wildlife Foundation’s California Oaks (CWF/CO) program issued a 2021 report that demonstrates the importance of oaks for California’s biodiversity, with a focus on species, subspecies, varieties, populations, distinct population segments, evolutionarily significant units, and clades that are federally and/or state designated as endangered or threatened (listed), or are candidates for federal or state designation.

California Department of Fish and Wildlife provided spreadsheets of sensitive species associated with oaks. Vertebrate data were derived from the California Wildlife Habitat Relationship (CWHR) information system, from which a list of 34 oak-dependent species, subspecies, distinct population segments, evolutionarily significant units, and clades was generated.

The plant and invertebrate tables were created utilizing two databases: California Natural Diversity Database (CNDDB), which is an inventory of the status and locations of rare plants and animals in California, and the oak woodlands layer of the Areas of Conservation Emphasis (ACE) system, which provides course-level spatial data on wildlife and vegetation, which is synthesized into thematic maps to help inform discussions on the conservation of biodiversity, habitat connectivity, and climate change resiliency. A 5% overlap threshold was established to exclude species, subspecies, varieties, and populations with a low average percentage overlap of all CNDDB occurrences with the oak woodlands layer in ACE. One hundred and thirty-four listed and/or candidate plant species, subspecies, and varieties, and twenty-six listed and/or candidate invertebrate species, subspecies, and populations were found to be associated with oaks.

Keywords

endangered, threatened, listed, Quercus, Notholithocarpus

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