Tuesday, November 14, 2006 - 2:15 PM

Assessing Root Turnover with Isotopic Measurements.

Erik A. Hobbie, Complex Systems Research Center, Univ of New Hampshire, Durham, NH 03824

The cryptic nature of soil makes assessing root turnover extremely difficult.  Radiocarbon techniques have indicated multi-year lifespans for fine roots, whereas minirhizotron images indicate much shorter turnovers.  Accounting for root order may help to reconcile these disparate measurements. Seasonal variability in the 13C content of recently fixed plant sugars suggests that 13C measurements on fine roots could be an additional tool to examine root turnover over seasonal time spans.  These measurements could help to constrain turnover times derived from other measurement techniques.  Here, 13C content in a temperate forest of foliage, phloem sap, roots growing through root screens, and roots of different orders were compared to assess the usefulness of this technique.