PARENT SESSION
Poster Session # 11: Disturbance Ecology.
Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Topkill and mortality of maple saplings following a prescribed fire in the Ohio Hills.
Rebbeck, Joanne*,1, Long, Robert1, Yaussy, Daniel1, 1 USDA Forest Service, Delaware, OH, USA
ABSTRACT- Since adoption of fire-suppression programs in the 1930s, the composition of mixed oak forests throughout the eastern US has been shifting from oak (Quercus spp.) and hickories (Carya spp.) to more-shade tolerant and fire-intolerant species such as red (Acer rubrum L.) and sugar (A. saccharum Marsh.) maples. The use of prescribed fire may improve oak regeneration. Previous research with prescribed fires conducted in southeastern Ohio showed that fire temperatures of 150°C or more caused 75% topkill of 3-6 cm d.b.h. (diameter at breast height) saplings and 55-65% of larger saplings (6.1-10 cm d.b.h.). Our objective was to estimate threshold bark temperatures during prescribed burns that elicit reduced vigor and mortality of saplings and small trees. In Spring 2001, aluminum tags coated with a series of temperature sensitive paints were secured on the lower stems of red and sugar maple saplings in thinned or unthinned 20-hectare study areas at three sites to estimate maximum bark temperature during a prescribed fire (N=240 saplings). Fourteen months after a prescribed fire, 37.0% of medium (3-6 cm d.b.h.), and 30.0% of large (6.1-10 cm d.b.h) saplings and 17% of small trees (10.1-14.2 cm d.b.h.), were topkilled but resprouted, while 9.3, 8.6, and 5.7% of medium and large saplings, and small trees, respectively, died and had not resprouted. Threshold bark temperatures for topkilling ranged from 100°C for medium and large saplings to 184°C for small trees. Mortality (no resprouting) was infrequent and commonly observed at bark temperatures of 400-483°C. Since achieving high intensity fires may not be practical, a series of frequent, numerous lower intensity spring burns (>100°C) which suppress repeated sprouting may be necessary to kill oak competitors such as maple.
Key words: competition, regeneration