PARENT SESSION
Poster Session #59: Fire Ecology II.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Evaluating alternative methods for measuring fire intensity.

WALLY, ALAA^*,1, MENGES, ERIC¹, ¹ Archbold Biological Station, Lake Placid, FL

ABSTRACT- Fire intensity is a function of both temperature and residence time and may affect community and population responses to burning. Unfortunately these parameters can be difficult to estimate consistently at the larger scales required of many ecological studies. We compared data from two inexpensive, easily deployed methods of estimating intensity (pyrometers using a lacquer series melting at 24 temperatures from 66 °C to 704 °C and calorimeters constructed of soda cans with water) to coincident metrics from thermocouples (10-m double-stranded wire leads). We sampled four fires with undisturbed upland Florida vegetation and vegetation pre-treated with logging, subcanopy felling, or mowing. Dataloggers had five thermocouples, each surrounded by 3 pyrometers and 3 calorimeters within a 16-m² area (N=70). We also placed single pyrometer-calorimeter pairs extensively throughout two sites (N=210). Pyrometers were significantly associated with all datalogger-derived metrics; the best models were peak one minute mean, number of minutes where mean was >150 °C and where max was >150 °C (R²=0.548, 0.560, 0.521). Pyrometers were worst at estimating maximum (R²=0.161) even though oven tests had found them to be accurate and many previous studies have assumed their accuracy. Calorimeters were significantly associated with area under the maximum >60 °C curve (R²=0.464), but were damaged at high residence times, and inconsistent at lowest intensity. Sites and treatments did not differ by mean or maximum, but the calorimeters were able to detect the significantly increased residence time associated with logging and subcanopy felling. The extensive sampling was able to illustrate different frequencies of low versus high intensities (un-melted pyrometers vs. damaged calorimeters) among treatments. Inconsistent performance among fires was a critical weakness of calorimeters, and to a lesser extent, pyrometers. Associations with datalogger metrics are promising, but further multi-fire studies incorporating calibrating devices are needed to refine calorimeters and pyrometer techniques.

KEY WORDS: fire intensity, pyrometer, calorimeter, Florida scrub and sandhill