Wildfire in the growing season is relatively frequent and interest is
increasing in using growing-season fire in management of tallgrass pra
irie, However, the influence of fire in the growing season on forage p
roduction and species composition, especially in mid-successional tall
grass prairie, is largely unknown, Our objective was to compare vegeta
tion composition and production on Loamy Prairie and Very Shallow ecol
ogical sites in mid-successional stages in response to late growing-se
ason fire at different frequencies. We applied 4 burning treatments (n
o burn, or 1, 2, or 3 burns in 5 years) in the late growing season in
southern Oklahoma during a series of years of above-average precipitat
ion. The sites were dominated at the beginning of the study by early-a
nd mid-successional species including prairie threeawn (Aristida oliga
ntha (Michx)), a species indicating a disturbance history, After the i
nitial burns in 1990, tallgrasses, little bluestem, and perennial gras
ses were reduced by burning on the Loamy site, Forbs were more product
ive on burned plots (1,980 kg ha(-1)) than on plots that were not burn
ed (1,290 kg ha(-1)) averaged across sites, Total production was not r
educed by burning in 1990, Growing-season burns in 2 consecutive years
had little influence on species composition or production as compared
to a single burn in 2 years, Warm-season perennial grasses other than
tallgrasses and little bluestem increased on the Loamy site, but decr
eased on the Shallow site, Production of cool-season perennial grasses
increased to almost 40% of total production on twice-burned plots ave
raged across sites, Other than the effect on cool-season perennial gra
sses, 2 burns over a two-year period had little effect beyond the firs
t growing season after the second bunt Twice-burned plots and plots bu
rned 3 times produced more forbs than either plots that were burned on
ce or not burned, Production of perennial grasses was opposite that of
forb production, Total production was not reduced on either site rega
rdless of fire frequency, Results indicate managers may expect a short
-term reduction in production of forage grasses and an increase in for
bs following late growing-season fire in mid-successional tallgrass pr
airies.