Post-Burn Differences in Solar Radiation, Leaf Temperature and Water Stress Influencing Production in a Lowland Tallgrass Prairie

Abstract

The influence of standing dead biomass on available solar radiation, leaf temperature (Tleaf) and leaf water potential (ѱleaf) of Andropogon gerardii in unburned tallgrass prairie was compared to burned prairie in eastern Kansas. The standing dead reduced photosynthetically active radiation incident on emerging shoots by 58.8% in unburned compared to burned prairie during the initial 30 days of the growing season. Aboveground production in unburned prairie was similarly reduced during this period (55.4%) compared to burned prairie. Leaf temperatures in A. gerardii were greater in unburned prairie than in burned early in the season, but were nearly equal by the end of the growing season. The maximum elevation of Tleaf in unburned prairie above burned was 9.5 C. The maximum unburned Tleaf measured was 41.5 C compared to 39.4 C in burned prairie. Lower windspeed adjacent to leaves in unburned prairie resulting in reduced convective cooling may have caused higher Tleaf in unburned prairie. Leaf water potential was significantly lower in unburned prairie than in burned prairie early in the season but was higher in unburned prairie by late season. The seasonal minimum ѱleaf in burned prairie was — 1.60 MPa compared to —1.45 MPa in unburned prairie. The combined effect of these post-burn differences in solar radiation, Tleaf and ѱleaf may be significant in contributing to the lower production in unburned compared to burned tallgrass prairie.