Seasonal Variation in Resprouting Ability of Native and Exotic Hardwoods in South Florida

Snyder, James

South Florida slash pine forests contain many hardwood species and bum at any time of year. At highest latitudes, it has been widely noted that the season of burning influence the response of hardwoods to fire. It is possible that the seasonal effects are not as pronounced in south Florida because the climate is more equitable and most species are evergreen. The objective of this study was to determine the seasonality in the ability of selected hardwoods to recover following killing of the above-ground stem. Fire is a difficult and expensive treatment to apply consistently over time. Instead of burning, we cut stems of five species (3 native, 2 non-native) at intervals to simulate the killing of stems by fire at different seasons. For most species, 144 individuals were marked at a single location and 12 randomly chosen individuals were cut near ground level each month for a year. Basal diameter, height, and aboveground biomass were measured initially and 2 yr after treatment. One year after cutting, we measured heights and basal diameters. Schinus terebinthifolius Raddi (non-native) had up to 33% mortality from cutting in June to October; other species showed little mortality at any time. Recovery of all species except Melaleuca quinquenerna (Cav.) S.T. Blake (non-native) was affected by time of cutting and was generally greatest following cutting in November to March. Guettarda liCabra (L.) Vent (native) biomass recovery after summer cutting was 40% of that after winter cutting. Dry conditions during April, May, and early June typically result in the highest intensity fires in south Florida and presumably the greatest impact on hardwoods. Results have implications for natural area fire management and exotic species control by mechanical means