Conifer encroachment study will inform efforts to preserve and restore North Coast oak woodlands

Abstract

Research news Conifer encroachment study will inform efforts to preserve and restore North Coast oak woodlands O Redwood National Park “It’s one of those things that creeps up on you — not a radical change, but just a clearly shifting trend,” said Dina Moore, a rancher in the Van Duzen River watershed near Eureka. Conifer encroachment on the North Coast mat- ters because it shrinks the already limited acreage of oak woodlands, one of the state’s iconic A 1987 study estimated that 30% landscapes. Oak wood- lands are valuable of the white oak woodlands in one for several reasons, region of Redwood National Park including grazing, hunting and habitat for had been lost to encroachment by oak-associated wildlife Douglas fir since 1850. communities. Several counties are prepar- ing oak woodland conservation plans, and the U.S. Fish and Wildlife Service and the Natural Resources Conservation Service have been providing grants to landowners to pay for tree removal to counter the trend. But these efforts have been hampered by both a Encroaching conifers poor understanding of the extent of conifer encroach- obscure a stand of ment in the region and a lack of research on the best oak in Redwood National Park. ways to address it. A 1987 study estimated that 30% of 12 CALIFORNIA AGRICULTURE • VOLUME 69 , NUMBER 1 Lenya Quinn-Davidson n California’s North Coast, landowners have noticed for decades the steady expansion of conifer stands into grassy oak woodlands. Fire suppression helps to create conditions that allow conifers to sprout and mature among oaks, as in this woodland in Redwood National Park. the white oak woodlands in one region of Redwood National Park had been lost to encroachment by Douglas fir since 1850, but there has been limited re- search since on the encroachment issue. Better information is coming this fall, with the publication of results from a three-year investigation funded by UC Agriculture and Natural Resources (UC ANR) and led by UC Cooperative Extension (UCCE) researchers. The project, “Tools for a changing landscape: Understanding disturbance and vegetation dynam- ics in Northern California oak woodlands,” is using aerial photography and satellite data to generate the first comprehensive map of oak woodland areas in Humboldt and Mendocino counties. Researchers will compare current conditions with historic photos and other data, along with field measurements of tree ages and other characteristics, to evaluate the extent and impact of Douglas fir encroachment. The project has established field sites in multiple locations to study climate, moisture and other condi- tions that may influence encroachment patterns. The information gathered will also help researchers to