Effects of fire on mortality and resprouting patterns of Stryphnodendron adstringens (Fabaceae)

Abstract

In the last 20 years, fire frequency in South America's largest savanna, the Cerrado, has increased by 41%. Although resprouting represents the main post-fire regeneration mechanism that allows plant species to persist in the Cerrado, under the new scenario of high fire incidence, small individual trees may not be able to regrow, while large individual trees may be subject to meristematic apical death or “topkill”. In this study, we evaluated the resistance and resilience of a tree species with a wide geographic distribution in the Cerrado, Stryphnodendron adstringens (Fabaceae) to non-prescribed fire and its resprouting dynamics. Seventy out of the 72 individuals of S. adstringens studied suffered topkill, indicating a low resistance to fire. To monitor the development and dynamics of resprouts for 17 months, we randomly selected 54 individual trees. Altogether, 143 resprouts were recorded in these 54 individuals during 3, 6, 10, and 17 months after fire, being 90% in the first 3 months. Larger individual trees had a larger number of resprouts and of larger sizes. Resprout mortality (14%) was higher in the 17th month post-fire. Multiple logistic regressions revealed that the survival probability of resprouts to the 17th month increased with their size but decreased with their number. We conclude that S. adstringens has low resistance but high resilience to, at least, a single fire. Also, there is a trade-off between the production of resprouts and their chance of survival. Thus, frequent fires can reduce the recruitment and persistence of the species.