How important is fire-induced disturbance in the maintenance of a threatened perennial forb,

Abstract

Context Many grassland forb populations have greatly diminished because their habitat coincides with prime agricultural land and remnants lack appropriate disturbance regimes. Aim The aim of the current study is to examine the survivorship, vegetative recruitment, biomass and sexual reproduction of S. papaverifolium in response to burning in one of a few natural surviving populations in Queensland. Methods We monitored the survivorship, vegetative recruitment, and reproduction of a rare native forb, Solanum papaverifolium, within a randomised replicated experiment by using 14 circular plots measuring 12.56 m2 (2 m radius). Key results Plant survival rate after 5 months was greater in the burnt plots (56%) than the unburnt plots (44%). Vegetative recruitment from suckers in the burnt plots was almost twice that in the unburnt plots. The probability of flowering was also enhanced by burning. Fruit set in new recruits was higher in the burnt plots (20%) than in the unburnt plots (5%). Whereas fruiting did not occur in unburnt plots for surviving plants that flowered, only 1% fruited in the burnt plots. Seedling production was not observed. Conclusion Previous studies have demonstrated that the subtropical grassland flora in the study region is unaffected by burning, whereas the present study suggests that some grassland species respond positively to burning. Implications Although fire increased flowering in this species, suggesting that fire may be a useful tool to stimulate sexual reproduction, ongoing research is required to understand the precise factors that promote flowering after burning and the barriers to seedling reproduction.