Susan Harrison, Professor
The major theme in my research is understanding the processes that shape and maintain plant species diversity at the landscape scale, where small-scale forces such as competition and facilitation interact with large-scale forces such as niche evolution and dispersal. Since 1997, much of my work has concerned serpentine soils, which support a rich endemic flora that contributes strongly to California's status as a global hotspot of plant diversity. My research seeks to understand the geographic patterns in richness and composition of the serpentine flora, and to assess the threats this flora faces from invasive species, climate change, and other causes. As well as using serpentine as a model system for ecological and evolutionary questions, this work aims to contribute to the better-informed conservation of a significant aspect of our natural heritage.
With Ellen Damschen of Washington University, I am currently resampling the vegetation transects that Robert Whittaker studied in the Siskiyou Mountains of southern Oregon in 1949-51. Our goals are to look for evidence of climate change and to determine whether serpentine vegetation has undergone different changes than 'normal' vegetation on diorite soils.
Recent research topics in my lab include:
- The importance of large-scale climatic gradients and evolutionary history to species richness at both the regional and local scales, using analyses of a large GIS- and field-derived dataset on the Californian serpentine flora (with Hugh Safford, Jim Grace, Josh Viers, and Kendi Davies). Please see:
- Effects of fire, livestock grazing, and invasive species on the native diversity of serpentine and nonserpentine vegetation (with Hugh Safford and others). Please see:
- Harrison, S. 1999
- Harrison, S, B.D. Inouye, and H.D. Safford. 2003.
- Harrison S, et.al. 2005.
- Harrison, S. 1997.
- Safford, H.D. and S. Harrison. 2001.
- Harrison, S., J. Maron, and G. Huxel. 2000.
- McKay, J.K. et.al. 2005.
- Batten, K.M. et.al. 2006
- Safford, H.D. and S. Harrison. 2004.
- Harrison, S. et. al. 2006.
- Scale dependence in the native and exotic species relationship (Kendi Davies). Please see:
- Effects of roads on grassland invasions (Jon Gelbard). Please see:
- Regional and local factors influencing the diversity of small serpentine wetlands, or seeps (Amy Freestone). Please see:
- Tests of niche versus propagule limitation in determining species distributions (Kara Moore).
Ongoing projects in my lab concern:
- the relative effects of climate, competition, and herbivory on serpentine endemics and other plant species (Barbara Going, Brian Anacker, and me);
- phylogenetic community structure in response to environmental gradients (Brian Anacker);
- effects of fire on rare plants (Matt Brown);
- analyses of temporal change in grassland communities in response to climatic variation, disturbance, and invasion (Sarah Elmendorf);
- collaborations with Dr. Hugh Safford of the US Forest Service on fire ecology and invasion biology.
Teaching and Advising
Every winter quarter, I teach ECL 208 (Conservation Biology), which is the core course for graduate students in the Conservation Biology Area of Emphasis in the Graduate Group in Ecology. I am also beginning an undergraduate course in Plant Conservation Biology. I offer graduate seminars on a variety of topics, ranging from field ecology to community phylogeny.
Service and Professional Recognition
I serve on the steering committee of the Blue Ridge - Berryessa Natural Area (BRBNA) Conservation Partnership, a regional conservation stakeholder group. I often provide advisory services to agencies such as the US Fish and Wildlife Service, US Bureau of Land Management, and California Department of Fish and Game. From 1998 - 2011, I served as the UC Davis faculty director for the University of California Natural Reserve System.
I serve on the Research and Publication Committees of the Ecological Society of America, was the 2006 Vice President of the American Society of Naturalists, and am an Honorary Fellow of the California Academy of Sciences.