Growth, Biomass, and Allometry of Resprouting Shrubs after Fire in Scrubby Flatwoods

Resprouting is advantageous for plants in pyrogenic ecosystems because it allows for quick re-acquisition of space after fire. Resprouting species build multiple stems during their lifetime and have an established root system, which may affect growth and biomass allocation and whether resprouts conform to predicted scaling relationships. We measured height, basal diameter, and biomass of stems of five resprouting shrub species in scrubby flatwoods sites in Florida, varying in time after fire (6 w, 1 y, 8-9 y, 20-21 y). Differences among species in size and allocation ratios tended to be greater in recently burned sites. Six weeks after fire, the dominant species, Quercus inopina, had the highest height/diameter and leaf/stem biomass ratios, which may contribute to the ability of this species to persist over fire cycles. The slope of the relationship between stem height and diameter was higher in recently burned sites than 8 to 21 y after fire, whereas the slope of the relationship between stem height and biomass was higher 8 to 21 y after fire than in recently burned sites. Height and biomass of resprouts generally scaled differently with respect to diameter and height than predicted by allometric theory, but biomass of resprouts, on average, scaled with diameter as predicted. Therefore, resprouted stems were taller for a given diameter and accumulated less biomass with height growth. In pyrogenic ecosystems, it may be more advantageous to grow tall, to maximize light capture, than to invest in strength to avoid damage because fire will eventually remove stems. Our results indicated that current allometric theory does not adequately represent scaling of growth and biomass of resprouting shrubs.