California forest and shrubland ecosystem changes in relation to fire, fuel hazard, and climate change

Fire is an integral ecological process, however fire’s impacts have been dramatically altered by people. In this dissertation I researched how fire ecology use to work and the vulnerability of ecosystems to fuel hazard reduction treatments by using a combination of experiments and landscape scale natural experiments throughout California. One of the best places to understand past fire behavior are the Wildland Fire Use areas in Sierran mixed conifer where I revealed that a forests’ environment, local-scale fire experiences, and regional fire experiences foster a rich, but sparse understory plant community. Throughout Yosemite National Park’s mixed conifer zone I examined the fire ecology of climate change refugia which have unique fire occurrence and severity patterns in frequent-fire mixed conifer forests of California’s Sierra Nevada: cold-air pool refugia have less fire and if it occurs, it is lower severity. In Northern California’s chaparral I examined fuel hazard reduction treatments and found that mastication and fire each have negative, yet unique influences on plant communities and fuel hazards which warrant examining other methods to protect people from chaparral fires. Overall these studies allow greater insight into our ecosystems and may help managers make informed fire management decisions.