VEGETATION RESPONSES TO SEASON OF FIRE IN TALLGRASS PRAIRIE: A 13-YEAR CASE STUDY

Fire regulates vegetation composition of fire-dependent grasslands in North American tallgrass prairies. We measured the vegetation response to prescribed fire seasonality by burning in two-month increments every two years, from 2004 to 2015, west of Stillwater, Oklahoma, USA. Fire exclusion or burning in any season led to an in increase in woody plant cover ranging from 18 % to 63 %, except for September through October, which showed no increase. Tallgrass cover increased with September through December burn treatments. Forb cover decreased with burning from January through April, but was highest in the September through October treatment. These vegetation responses suggest that land managers, policy makers, and researchers should consider the benefits of burning outside of the traditional late-winter to early-spring window, providing that they have the ability to increase the number of burn days and reduce temporal concentrations of smoke.