REU: Mechanisms of Below-ground Competition in Plants: Linking Form and Function

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This research will examine how the morphology and demography of the fine root system of plants enables the acquisition of two limiting soil resources: water and nitrogen. The ability of plants to alter fine root morphology (length, width, branching pattern, production of root hairs) and demography (birth, death, and elongation rate) is thought to affect the rate at which then encounter and exploit soil resources. The overall hypothesis is that species differences in fine root morphology and demography regulate their ability to acquire below.ground resources and therefore compete for these resources. The ability to encounterand exploit resource patches that vary in space and time must be linked to root morphology and dynamics. Several specific hypotheses will be tested in a series of greenhouse experiments. Fine root dynamics will be measured using in situ video imaging of minirhizotrons and summarized using life-tables and projection matrices. By varying the availability and spatial distribution of water and nitrogen, and by using 15C as a tracer, we will be able to measure the relationship between fine and root morphology and dynamics and resource acquisition. This research is novel and innovative because it utilizes new technology to understand how resource availability drives fine root demography. Until now, virtually all ecological investigations have either ignored fine roots (a major carbon sink), or quantified them in one or aseries of static observations. This project will make significant progress toward the development of a more mechanistic understanding of competition for soil resources in terrestrial plants.