The Compounding Consequences of Climate Change and Wildfire for a High Elevation Wildflower (Saxifraga austromontana)

Climate change disproportionately impacts alpine ecosystems. Many species unique to high elevation habitats are at great risk of population and species level extinctions due to changes in the climate, partially forced by anthropogenic emissions of greenhouse gases. The direct effects of climate change, such as increases in temperature and altered precipitation patterns, also induce indirect effects, defined as changes in ecological interactions and disturbances. One of the most eminent and tangible indirect effects of climate change in western North America is a startling (6x) increase in rare, large wildfire events since 1970; a number projected to increase over the century. Wildfires have moved up in elevation into the alpine, regions where fire was once extremely rare or absent, due to elevated temperatures, early snowmelt, and ultimately drier fuels. My thesis aims to quantify and qualify the compounding impacts of climate change and wildfire on high elevation ecosystems, using the wildflower species Saxifraga austromontana Wiegand (Saxifragaceae) as a study system. First, I modeled the direct impacts of climate change on S. austromontana using Species Distribution Models (SDMs) to precisely estimate the present and future climate envelope of the species, projecting the average conditions for 2041-2070 under a moderate and realistic emission scenario. In doing so, I discovered that many of the historic records I used, archived in herbaria (plant museums), did not contain accurate geographic coordinates. Thus, I developed a novel standardized method to prepare historic occurrence records (museum and herbarium collections) for use in spatial analyses. I present this new method, the Spatial Analysis Georeferencing Accuracy (SAGA) protocol, and test its rigor against other previous methods in Chapter 2: Why Georeferencing Matters: Introducing a Practical Protocol to Prepare Species Occurrence Records for Spatial Analysis. Utilizing this new method, combined with an arduous five-month field experiment, high resolution SDMs, and fire predictive models, I completed the first documented study on the compounding impacts of climate change and wildfire on a high elevation species. Chapter 3: The Compounding Consequences of Climate Change and Wildfire for a High Elevation Wildflower is the culmination of my efforts at Western Washington University and in the field traversing the latitudinal range of the Rocky Mountains collecting data. I worked closely with my exceptional adviser, Dr. Eric DeChaine, and collaborated with my brilliant committee members to prepare two manuscripts for submission to scientific journals. This body of work has the potential to advance the utility of invaluable historic records for spatial analyses, and reveals a novel understanding of the compounding impacts of climate change and wildfire on North American alpine ecosystems.