Vitality and turnover of fine roots in spruce stands
DFG FOR 562 TP 6: (2005-2008)
From 04/2005 to 03/2008Principal Investigator: Christoph Leuschner, Dietrich Hertel
Staff: Dirk Gaul
Grant: FOR 562 Dynamics of soil processes under extreme meteorological boundary conditions
Fine roots represent one of the main sinks for carbon and nutrients in trees. In addition, dying fine roots are an important source of carbon for the decomposer food chain in the rhizosphere of forests. This project investigates the dynamics of fine roots of a montane spruce stand under the influence of experimental drying/re-wetting and freezing/thawing cycles. Growth, death and turnover of fine roots are investigated with several independent methods including 14C-dating, direct observation with mini-rhizoscopes, root-window observation, and growth analysis by sequential coring. Main study aims are (1) to investigate the sensitivity of fine roots to soil drying/re-wetting and freezing/thawing events, (2) to monitor changes in fine root morphology (branching patterns, periderm structure) and physiology (content of non-structural carbohydrates) and (3) to quantify fluxes of C and N into the rhizosphere with the death and decay of fine roots that were shed due to extreme climatic events. We attempt to recognize thresholds in the stress response of spruce fine roots to soil drought and frost, and to quantify the potential for root regeneration with re-wetting and thawing. The measured fluxes of C and N with dying fine roots serve the modeling purposes of projects 3, 4 and 5.