My research focus is on plant eco-physiological responses to changes in water availability (spatially, temporally, or driven by climate changes). Particularly, I'm interested in the mechanims of drought tolerance by grassland and savanna species (structure / function) as well as the theory of competition/ facilitation for water between trees and grasses. Thus, I enjoy spending my time addressing questions linking resource availability - physiology - patterns of productivity, with the goal of improving our ability to scale energy dynamics and hydrological processes from the plant- to ecosystem-level.
Personally, count me among the prairie dogs, meadowlarks and the bison; I [heart] grasslands. These systems exist within an interface of climatic variability and frequent disturbance (fire and grazers). Grass species are deceptively simple, but their unique physiology and form is adapted to environmental stress and disturbance. Despite abiotic and biotic pressures, grasses can grow like weeds (har har har) and develop dense canopies and high biomass. The environmental and biotic complexity of grasslands provides a challenging (mentally and physically) and enjoyable system to study. There is nothing better than spending a day on the Konza Prairie in the Kansas sun.
CV (last updated - May, 2012)
My research focuses on plant community responses to global environmental change with an emphasis on interactions between native and invasive species. Currently, I am studying plant responses to climate change and nitrogen deposition in the Front Range of Colorado, where both winter precipitation and nitrogen availability have increased in recent decades. My work will examine how native and invasive plants in this system compete for water and how changes in precipitation and nitrogen availability might affect species interactions. I also maintain active long-term research plots in the eastern Sierra Nevada (where I worked on my dissertation) to measure plant community response to increases in nitrogen deposition and changes in snowpack.
My primary home is at CU - INSTAAR, but every now and again I make the trip east to Manhattan.
My research investigates how physiological mechanisms of plant water-use drive larger scale ecological phenomena such as plant survival and productivity, patterns of species coexistence, and earth-atmosphere exchange of fluxes in grasslands. For example, I am linking root structure with water-use patterns (multi-scale hydrological fluxes), understanding mechanisms of competition and facilitation for water among coexisting species, and predicting the responses of these processes to hydrological variation associated with global climate change. For my dissertation I am using whole-plant sap flux and stable isotope techniques in a tallgrass prairie to ask the following questions: (1) What are the biological and/or environmental drivers of hydraulic redistribution? (2) Do patterns of hydraulic redistribution differ among functional types (shrubs, forbs, and grasses) and ecological gradients (topography and grazing treatments)? (3) How does this mechanism influence competition and facilitation for water among different functional types? (4) How does hydraulic redistribution influence landscape-level carbon and water fluxes? I am also intersted in other hydrological fluxes in this system (night-time transpiration), as well as identifying the adaptive significance of drought avoidance (hydraulic redistribution) versus drought tolerance strategies, particularly in the context of global climate change.
CV (last updated - Aug, 2013)
Rory began in August, 2014 having just completed his MS from BYU. At present, Rory's dissertation research is undefined, but will likely focus on mechanims of woody plant encroachment in grassland ecosystems.
Rachel started working with us in Jan., 2014. Rachel's research is focused on comparing source-water use among trees and grasses in the riparian watersheds of Konza Prairie. Do riparian trees use streamwater or compete with grasses for shallow water? We'll soon fine out! Rachel is also the primary technician for SIMSL, and Jesse's right-hand person for help around the eco-phys lab.
Zak Ratajczak (2011-2014) Ph.D. - Biology
Currently: NSF Post-doctoral Fellowship, University of Virginia and the Stockholm Resilience Center
Troy Ocheltree (2008-12) Ph.D. - Agronomy and SIMSL Manager
Assistant Professor, Dept. Forestry and Rangeland Stewardship, Colorado State University
Jeff Hartman (2009-11) M.S. - Biology
Currently: University of Nebraska-Lincoln (w/ David Wedin)
Jacob Carter (2008-10) M.S. - Biology
Currently: University of Kansas (w/ Joy Ward)
Ben Ketter (2012-2014) - now MS student at U Missouri
Gracie Orozco (2009-2014) - Environmental Engineer, Victoria, TX
Laura Kemp (2011-2012) - scientist at The Land Institute in Salina, KS
Whitley Jackson (2008-2012) - now at KU-Med School in KC
Teall Culbertson (2008-2011) - now a VetMed student at K-State
Andy Muench (2014) from U Wisconsin-Madison
Ben Ketter (2013) from K-State
Annie Klodd (2011) from Grinnell College
Rachel Wieme (2010) from St. Olaf's College
Zak Ratajczak (2009) from Vassar College
Laura Kangas (2008) from Michigan Tech