Blue Oak Habitat
Blue oaks are common in the foothills of Sequoia National Park, which experience a drier and warmer climate than the higher elevation habitats where sequoia trees are found. The foothills are composed of chaparral and woodland plant communities that are able to tolerate the Mediterranean climate: dry, hot summers and cool, wet winters.
Why monitor blue oaks?
The heat-tolerant blue oaks respond to climate. Typically, blue oaks shed their leaves each year, but in wet years their leaves can stay green all year. In very dry years, blue oaks can forego acorn production to reduce their need for water. Blue oaks are an ideal species to monitor for phenology because their life cycle stages are sensitive to changes in weather and climate, and their phenophases are easy to recognize.
A host of species rely upon blue oak acorns as an important source of food. Birds, squirrels, insects, deer and even bears eat acorns when they are available. Acorn woodpeckers stockpile acorns for the winter months by storing them in dead trees and branches called granaries. Therefore, variation in acorn production due to changes in climate may have a serious impact on the park’s entire food web.