A Time-Dependent Model of Fire Impact on Seed Survival in Woody Fruits

Abstract

Many plants rely on the survival of seed in woody fruits for their post-fire regeneration. A mathematical model of seed survival in woody fruits was constructed using heat-flow equations with time-dependent temperature inputs. The model was then used to predict the survival of seed in fruits exposed to both laboratory heating and field fires as reported in the literature. Due to a lack of data for woody fruits, thermal diffusivity values appropriate to bark were used as inputs. The lethal threshold temperature for seeds was taken as 70°C which is at the lower end of the range reported in the literature. The inclusion in the model of thermal arrest within fruits gave the upper bounds for estimated times of seed survival. The model yielded reasonable predictions of seed fate when compared with experimental results. It was shown that the location of seed within the fruit is not critical to its survival provided it lies within the central core of the fruit. The applicability of the model was also demonstrated using published time-temperature curves from experimental fires.