The University of California Natural Reserve System is the largest and most productive network of university field stations in the world. Forty-one reserves across California protect examples of most of the state’s ecosystems for research and teaching. Each reserve is administered by one of the UC campuses; the UC Davis Natural Reserve System manages six sites. Established in 1965 in the face of ever-expanding land development in the state, the Natural Reserves have served as outdoor laboratories and classrooms for thousands of scientists and students. Through the decades, they have accumulated long-term data sets of ever-increasing value, especially as scientists struggle to understand the effects of climate change and land-use changes in California landscapes.