Quaternary International 193 (2009) 90–98 Developing an approach for using the soil phytolith record to infer vegetation and disturbance regime changes over the past 200 years Lesley R. Morris à , Neil E. West, Fred A. Baker, Helga Van Miegroet, Ronald J. Ryel Department of Wildland Resources/Ecology Center, Utah State University, 5230 Old Main Hill, Logan, UT 84321-5230, USA Available online 12 September 2007 Abstract Historical ecology is a field of research that seeks to explain how ecosystem change is manifest upon the landscape over time. This interdisciplinary synthesis of information draws from the human and the biological archive. Historical ecology helps characterize reference conditions and the historic range of variability in ecosystem structure that is useful in understanding ecosystem dynamics and function, provides input to resource managers, and guides restoration efforts. The methods in historical ecology cover a wide range of temporal and spatial scales. However, the evidence for time scales of less than 200 years is largely limited to the human archive and dendrochronology. Additional approaches for this more recent time period could provide important information for understanding the vegetation changes in the past 200 years especially where dendrochronology is not applicable. This research seeks to expand the biological evidence for inferring vegetation and disturbance regime changes in the Western United States since settlement in the 1800s by developing an approach that combines the human archive and soil phytolith analysis. We examined the human archive for vegetation and disturbance regimes change in the City of Rocks National Reserve, Idaho, US. In addition, we examined the phytoliths of native and introduced species in the area and looked at how well the soil phytolith record reflects recent wildfires. Our results indicate that this combination of history and soil phytolith analysis will be a useful approach for inferring vegetation and disturbance change in ecological histories. r 2007 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction Across the Intermountain West of the United States, land management agencies are struggling with the issues of landscape change. In the Great Basin region, woody species are reported to be increasing in dominance at the expense of the grass and herbaceous understory in both sagebrush steppe (Miller et al., 1994) and pinyon–juniper woodlands (West and Young, 2000). Changes in ecosystem function, such as water relations (Ryel et al., 2003, 2004; Brown et al., 2005; Ponton et al., 2006), may also be affected. Invasive plant species, such as annual grasses, are further altering landscape dynamics (Miller et al., 1994) and many question the causes of what seem to be increasingly frequent and devastating wildfires (Miller and Tausch, 2001). Land managers often seek information about the past to understand how to manage for the future (Swetnam et al., 1999). In addition, knowledge of past plant community assemblages and historic dynamics are important for ecologists in studying ecosystem function. Historical ecology is an emerging and interdisciplinary field of study that seeks to describe and explain the changes and processes that have created current landscapes through a synthesis of information derived from human records and biological data (Russell, 1997). The resulting ecological histories of landscapes provide an understanding of historic conditions, the range of variability and ‘‘reference conditions’’ that are particularly useful in restoration efforts (Egan and Howell, 2001) and for setting manage- ment priorities and goals (Swetnam et al., 1999). Historical ecology requires synthesis of information from the human and biological archives. The human archive records historic conditions within written, oral and photographic sources. The biological archive is the record of historic conditions contained within the natural environment and is investigated through dendrochronology, packrat middens, palynology and soil phytolith analysis. The methods in ARTICLE IN PRESS 1040-6182/$ - see front matter r 2007 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2007.08.040 à Corresponding author. E-mail address: lesleymorris@cc.usu.edu (L.R. Morris).