Oak Woodlands
Oak Woodlands is the apex community, and coast live oak is the indicator species here. These oaks have strangled their competition by capturing most of the sunlight for photosynthesis, but an understory develops beneath their branches and in small clearings between trees. I propose a working definition: looking under an oak tree, if you see:
- manzanita or black sage
- a chaparral or scrub community is transitioning to woodlands
- poison oak
- it's Oak Woodland
This coast live oak specimen sports nine trunks and more rising branches. Oaks are well known for crown-sprouting. The root crown, a swelling remaining from the initial acorn, often survives a fire. Multiple suckers spring up, and several develop into separate trunks. According to the USDA, a controlled fire in Monterey County killed 20% of live oak saplings. The remainder were top-killed, lost everything above the surface, but had three feet of growth in two years. In a thick forest most trees strive for vertical growth to reach more sunlight. Coast live oak has an additional response to fire threat: it has the thickest bark of any California black oak. This bark serves as insulation against heat damage, so the main trunk of mature oaks frequently survive wildfires.
Growing in isolation, for example, an oak tree may spread lower branches rapidly. These lower branches avoid the shade of the main trunk and help the tree cover more surface area, and thus, more gather more light for photosynthesis. Living for centuries, a coast live oak rarely exceeds 30 feet in height, but its branches will spread to cover hundreds of square feet of ground. These oaks have several reasons to develop multiple trunks, and this propensity is noted in Santa Barbara County.
Maps suggest that BMER holds interior live oak, Quercus wislizeni, but I have never recognized one. I have seen canyon live oak, Quercus chrysolepis, in the hills around Hidden Lake.
The coast live oak has developed several strategies to survive frequent fire. With inexorable growth, it eventually dominates the plant communities. Only repeated fires may halt its spread. Without the disturbances of fire or grazing, a local study found that live oaks overwhelmed coastal sage scrub at a rate of 0.3% per year. BMER could be a nice forest in just a few centuries.
