California’s oak woodlands have been dramatically reduced over the past two centuries. Numerous factors have contributed to this decline including the encroachment of coniferous species into oak habitats following the disruption of historic fire regimes. Oaks are slow-growing, shade-intolerant species that can be rapidly overtopped and suppressed by faster growing conifers. Initially, suppression leads to crown dieback in the oaks and reduces acorn production. Over time as more of the oak crown becomes shaded the oaks eventually die.
On the dry east side of the Scott River Valley in Siskiyou Co., CA, juniper encroachment poses a major threat to the health and function of oak habitats. To address this issue the U. S. Fish and Wildlife Service, the Natural Resources Conservation Service, and Lomakatsi Restoration Project partnered with the Scott River Ranch to reduce juniper encroachment on 91 acres of oak habitats. Treatments focused on removing junipers growing within 10 feet of an oak to reduce competition for resources including sunlight, water, and nutrients. This approach removed approximately 85 percent of the junipers while leaving scattered large junipers for habitat diversity. An additional 164 acres of juniper reduction are planned for the ranch beginning in 2018.
Before (Left): Oak encroached by juniper pre-treatment on the Scott River Ranch, Siskiyou Co. CA, October 2014
After (Right): Open grown oak free from competition following juniper reduction treatments on the Scott River Ranch, Siskiyou Co. CA, October 2015.