Conservation of California Walnut in the Eastern Santa Monica Mountains. This item is unavailable.Conservation of California Walnut in the Eastern Santa Monica Mountains

California walnut (Juglans californica) is a rare species and keystone component of two Sensitive Natural Communities: Coast Live Oak–California Walnut Woodland and California Walnut Groves. The species is under assault from residential and commercial development throughout its remaining range in southern California. In this report we address a region within the eastern Santa Monica Mountains that is subject to ongoing development pressure in which steep parcels are now being targeted for residential construction, threatening the remaining walnut groves and oak–walnut woodlands. The City of Los Angeles issues permits to remove California walnut trees at a rate of one mature tree every 7.2 days.

We present background information about the ecology, distribution, and conservation status of California walnut and review the mechanisms that should be, but are not, protecting it in the environmental review process under California law. Although the City of Los Angeles has a native tree protection ordinance, in practice the ordinance does not preclude removal of trees for development; does not provide for any replacement of habitat area, which would be essential for mitigation of biological impacts; and does not even require that any replacement trees are of the same species as the species removed. As a result, the area supporting California walnut and its associated natural communities continues to shrink and become more fragmented.