The research that I and my students conduct is at the nexus of land use change, watershed science, social-ecological systems, and environmental resource management, with an emphasis on human-environment interactions. I began my research career as a fluvial geomorphologist (MS in Geology) studying hydrology and sediment transport in a highly-urbanized watershed. During my PhD research, I broadened my perspective on rivers and investigated links and feedbacks among hydrology, geomorphology, and ecosystem process at multiple scales. The most significant product from my dissertation research was the Benthic Light Availability Model (BLAM), which quantified aquatic light availability and was the most comprehensive model in this regard. BLAM is increasingly been used by researchers for a wide variety of applications. Following my graduate studies, I continued to broaden my perspectives and toolset during my Postdoc at the Appalachian Lab, University of Maryland Center for Environmental Science, where I stepped out of the rivers and began to look at entire landscapes over large, diverse regions. This landscape perspective has continued into my current research, where I now focus on sustainable water resources, protected places, and ecosystem services across broad scales.
Our research approach is to use tools and concepts from multiple disciplines to understand how processes (both human and physical) interact across scales. These cross-scale interactions (CSI) occur when processes at one spatial or temporal scale interact with processes at finer or broader scales. In systems where CSI are connected, a change in an environmental driver (e.g. climate or land use) can result in positive feedbacks and cascading events that lead to dramatic and widespread changes in system dynamics (Carpenter and Turner 2001; Peters et al. 2007; Soranno et al. 2014). Through a combination of studies, we have shown how land use changes at the intermediate (conversion of a watershed from forest to agriculture) and fine (removal of riparian trees along a river segment) spatial scales interacted to change two fluvial processes (aquatic light transmission and sediment runoff) that also interact at both fine and intermediate spatial scales. Given that rivers form highly connected networks across the landscape, these positive feedbacks ultimately led to changes in water quality and primary productivity at fine scales that propagated to intermediate and broad spatial scales. Using a relatively new statistical technique (power spectral analysis) on daily discharge from 87 watersheds across the Eastern U.S. Piedmont in combination with other geospatial data, we demonstrated how CSI between rainfall characteristics and landscape characteristics dictate runoff patterns across a wide range of temporal scales (Julian and Gardner 2014). We have continued to develop applications for CSI, and were recently funded by NSF-GSS to investigate CSI among climate, land use, and water quality in intensively used landscapes in New Zealand.
Other current projects include: