Document: JAM-3-68-44

Fuel consumption, fire temperature, and tree mortality following different seasons of burning in subtropical pine forest.

SNYDER, J.R.*, H.A.BELLES and J.N.BURCH

USGS, Biological Resources Division, Ochopee, FL 34141 ¹

Abstract:
A series of 16 burns has been conducted as part of a long-term study of season and frequency of burning in South Florida slash pine forest. The study area is a mosaic of unlogged pine forests (Pinus elliottii var. densa) and cypress wetlands. Burn units are relatively large (>50 ha) and contain three 1.0 ha permanent tree plots in which a total of >16,000 trees have been mapped and tagged. Prescribed burns are conducted in the dry season (winter), early wet season (spring), or mid wet season (summer). Fuels (consisting of litter <2.54 cm diameter, herbs, shrubs, and palm leaves <2.0 m above ground level) are measured before and after burning . Fire temperatures are measured with temperature-sensitive paints on small steel plates placed at ground level. Fuel loadings averaged 940 g/m² and fuel consumption averaged 670 g/m². Fine litter, dominated by pine needles, comprised 78% of the mass consumed while herbs, palms, and coarse litter (>0.6 cm and <2.5 cm) each made up 5 to 10% . Fire temperatures were relatively mild, with means ranging from a low of 212^oC during mid wet season burns to a high of 222^oC after early wet season burns. Mortality of pine trees >5 cm diameter in the first year after the burns was very low. The greatest number of trees died after mid wet season burns (2.7%). South Florida slash pine is extremely resistant to fire and can withstand complete scorching of the crown. Patterns of mortality are more associated with localized fuel conditions than with season of burning.

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This abstract is being presented at: 10:30 AM in session:
Poster Session #12: Disturbance Ecology.