September 19, 2013
Wildfire: friend or foe? This is a big question to ask oneself when thinking of the wildness of Yosemite National Park. Within the Sierra Nevada, fire has been an integral part of the ecosystem for thousands of years. During that time the flora and fauna have adapted to a Mediterranean style climate of hot and dry summers allowing for a vastness of fire tolerant plants to adapt to that natural cycle. A unique plant that has a rich and distinctive life cycle within this unique ecosystem is buckbrush Ceanothus, Ceanothus cuneatus. Buckbrush commonly thrives in areas that have burned in the past. So, to this low-lying evergreen shrub, its answer to the aforementioned question might be simply: "a friend." With stiff sliver colored branches that imitate thorns, wreaking havoc on a casual hikers legs and feet, buck brush will produce seed capsules that can lay dormant for a significant period requiring fire to open the capsules and help germinate the seeds. The capsules, when exposed to heat produced during fire, pop open and the seeds (approximately 1mm in length) disperse amongst the ash bed of the burned area. The nutrients that are replenished in the soil from a fire, combined with limited competition from other flora, allow for buckbrush seeds to take root and dominate the fire scared landscape. Some lesser known fauna of Yosemite, Harvester ants, have been known to gather and cache these seed capsules for food into the winter months which helps with seed dispersal once a fire burns that particular area.
Buckbrush also is home to a few different animal species in Yosemite; species such as the Sooty grouse, California mule deer, and the common California ground squirrel. So the next time you are hiking through one of the many fire-scarred areas of Yosemite's wilderness and wondering what plant has thrashed your legs with tiny scratches, look distinctly at this short, evergreen shrub with stiff branches and small leaves and think back to the question, "Wildfire: friend or foe?" and see what answer you come up with.
Top & Bottom: Buck Brush, Ceanothus cuneatus, growing in a recent burned area in Yosemite's mid-elevation forests.
Middle: Buck Brush branch showing stiff, silver colored bark imitating thorns.