Using soil phytolith analysis to study 200 years of vegetation and disturbance regime change

Historical ecology seeks to explain how change is manifest upon the landscape over time.  The interdisciplinary synthesis of information drawn from human and biological archives helps characterize reference conditions, define historic range of variability, and guide restoration efforts with a more complete understanding of ecosystem dynamics and function.  Since human actions are rapidly becoming the drivers of ecosystem change, restoration requires an understanding of pre-settlement conditions, alterations from land use history and impacts of climate change. Methods used in historical ecology cover a wide range of temporal and spatial scales, however, the techniques for less than 200 years are limited to the human archive and dendrochronology evidence.  This research seeks to expand biological techniques for examining vegetation and disturbance regime changes in the West by combining the human archive with soil phytolith analysis. We catalogued 130 native and introduced flora of the Great Basin region and found several unique phytoliths. We examined the ecological history of the City of Rocks National Reserve, Idaho, US since settlement in the 1800s. We then used known historical changes in vegetation and disturbances (e.g. fire history) to test the sensitivity of the soil phytoliths to record these events and for inference back in time.  Soil phytoliths reflected differences between burned and unburned sites. Our results indicate that soil phytolith analysis is a useful biological tool for inferring historic vegetation and disturbance regime change within this time frame.