The effect of localized nitrogen availability on root lifespan

Tom installing minirhizotrons

Tom installing minirhizotrons

PhD in Ecology (2014)

Tom was partially supported by the National Science Foundation

Tom works in the Eissenstat Lab as a Senior Research Specialist.

The lifespan of roots is of broad interest in ecology. Because fine roots account for as much as one third of global net primary productivity (Jackson et al. 1997), their lifespan is of major importance to carbon and nutrient cycles and is a key link to longer-term changes in soil organic matter and ecosystem carbon balance (Norby and Jackson 2000). Moreover, competition below ground occurs widely in plant communities and often dominates over competition above ground (Wilson 1988). Belowground competition may be largely associated with rapid exploitation of resource patches and control of the patches to the detriment of neighbors (Eissenstat and Caldwell 1988; Robinson et al. 1999). While rapid exploitation of resource-rich patches such as nitrogen has been a major focus of research (Robinson 1996), much less is known about how patch exploitation is influenced by root longevity.

To gain a better understanding of the relationship between nutrient availability and root lifespan, I have been conducting a multi-year root demography study of co-occurring Northeastern temperate tree species, using clear acrylic minirhizotron tubes installed at a common garden of trees planted at the Pennsylvania State University's Russell E. Larson Agricultural Research Center. By applying nitrogen fertilizer to a subset of the minirhizotron tubes, I have been investigating root lifespan, plasticity and patch proliferation across multiple tree species that vary widely in root anatomy.