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| We currently have several projects underway that examine the influence of biological and environmental processes on the isotopic composition of organic matter in plants. These projects are directed at (a) the mechanisms that determine the isotopic composition of plants or (b) applying this knowledge to understanding ecological processes and ecosytem dynamics. |
| The cellulose in tree rings project examines the basic biological and environmental processes that determine the carbon, hydrogen, and oxygen isotope ratios in cellulose. This project is focused on determining fractionation factors and isotopic exchange at the leaf, tree ring, and root levels in order that we can then use isotopic analyses to reconstruct both environmental history and the integration of metabolic processes from tree rings or from leaves. The project includes modeling, long-term greenhouse experimental tests, and field validation studies.
The boxelder project focuses on understanding how the population dynamics and individual metabolic histories of a dioeceous riparian tree are influenced by changes in ground water and stream water availability. The ponderosa pine monsoon project focuses on understanding long-term shifts in the northern limits of the Arizona monsoon boundary and how changes in monsoon intensity have influenced tree growth and ecosystem dynamics. The northern limit of the Arizona monsoon passes through central Utah; north of this boundary there is very little summer moisture input and the ecosystems rely primarily on moisture from winter/spring storms. The corn project focuses on using stable isotopes to reconstruct the water source(s) used by ancestral native American Indian groups in Utah. The focus is on understanding the extent to which monsoonal moisture sources were critical for corn production in central and southern Utah and to the possibility that shifts in the northern monsoon boundary may have been associated with the loss of the Anasazi from southern Utah. Stable isotope analyses form an integral component of other ecological studies in the lab and the reader is encouraged to explore the aridland, air, C3/C4, and forensic pages. We have also been involved in other aspects of stable isotopes that may be of interest:
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