It is hard to overstate the importance of the California black oak (Quercus kelloggii) to Yosemite National Park. With so many other icons, it may be easy to overlook the black oak, but it is one of the most important cultural, biological, and scenic resources in the park. The long human history in this place is largely dependent on the black oak, which served as a source of food for the first peoples of the park. Many animals eat the black oak acorns, including the iconic black bear, deer, acorn woodpeckers, and squirrels. Additionally, the scenery that made this place famous has always been accented by the spring green and yellow fall leaves of the black oaks. Needless to say, park scientists are carefully monitoring such an important resource.
Several years ago, a population study of the black oaks looked at age or size structure of the trees. That research determined that our black oak groves are dominated by mature oak trees, with not enough seedlings and saplings being recruited, which is the addition and retention of new trees into the oak groves, to replenish the groves as the older trees die off. A new study, funded by the Yosemite Conservancy, began this week to try to figure out what could be keeping the seedlings and saplings from becoming mature trees. One hypothesis is that deer and rodents may be eating so many acorns and seedlings that not many survive past that stage. The study is simple; three acorns will be planted at many different sites in the existing oak groves in Yosemite Valley. Of the three acorns, one will be protected from deer and rodents, one will be protected from deer only, and the third will not have any special protection. Continued monitoring of these sites will help us understand how the deer and rodents are affecting black oak recruitment in Yosemite Valley.
Do not disturb! Acorns at work!
Many sites like this one were set up this week in the Yosemite Valley oak groves. In this photo you can see a large fence, which protects two acorns planted inside from deer. One of those acorns is inside the small cage, which extends underground to protect that acorn from rodents as well. A third acorn was planted outside the fencing.