PARENT SESSION
Thursday, August 10, 5:00-6:30 pm
Poster Session 23 - Arid and semi-arid ecosystems: deserts, grasslands, shrublands, and savannas
Exhibit Hall, Ballroom Level, Cook Convention Center
Effects of annual fire and mowing on fine root dynamics in tallgrass prairie.
Kitchen, Duane*,1, Blair, John2, 1 Rockford College, Rockford, IL, USU2 Kansas State University, Manhattan, KS, USA
ABSTRACT- The dynamics of fine root production and turnover have important implications for ecological patterns and processes at scales ranging from microscopic to global, and these belowground processes are influenced by fire and herbivory in a variety of ecosystems. We examined the effects of long-term annual spring burning and summer mowing on root dynamics in a replicated factorial experiment in tallgrass prairie at the Konza Prairie Biological Station in northeastern Kansas, USA. Using deep soil cores and minirhizotron observations made over three field seasons, we determined that fire and mowing acted individually and interactively to significantly influence patterns of fine root biomass, root C and N content, root length density (RLD), production, mortality, and turnover of fine roots. Observed fine root parameters varied significantly, and generally declined, with depth. Annual burning increased fine root biomass (50%), C storage in roots (40%), RLD (100%), and overall fine root production (45%) and mortality (35%). Annual burning also resulted in a deeper distribution of roots, and a decrease in fine root N content and fine root turnover (0.76 year-1 compared to 1.01 year-1 in unburned unmowed plots). Mowing did not affect root biomass or RLD in unburned plots, but significantly reduced root biomass and RLD (30% and 60%, respectively) in burned plots, and also reduced root N content and the relative depth distribution of roots. The observed belowground responses to annual burning and mowing and soil depth have important long-term consequences for key ecosystem processes in tallgrass prairie.
Key words: fine root dynamics, tallgrass prairie, minirhizotron