Post-fire regeneration strategies in a frequently burned Cerrado community

Abstract

Aim: Fire is a natural disturbance in many ecosystems throughout the world where plant populations can persist by the resprouting of individuals and/or by recruiting from seeds. We evaluated the post-fire regeneration response for 41 coexisting species, including grasses, forbs, and shrubs, from an open Cerrado community (campo sujo) in Central Brazil. Location: The study was conducted at the Reserva Natural Serra do Tombador (RNST) in Central Brazil. The vegetation of the study area is characterized by a continuous herbaceous layer dominated by grasses and scattered shrubs, which produces fine fuel loads that can burn frequently. Methods: We examined both resprouting ability after experimental fires, accounting for bud location, and seed response to heat shocks caused by fire, where seeds were subjected to heat shocks of 100°C for one and three minutes, 200°C for one minute, and a control (untreated seeds). Results: All species were able to resprout (R+) after fire, mainly from buds located in underground structures, but also from aerial and basal buds. Seeds of most species tolerated heat shocks of 100°C for one and three minutes, but heat treatments of 200°C decreased seed viability of nearly 50% of species. Seven species, all of which had dormant seeds, showed heat-stimulated germination. In sum, 81% of the community was classified as R+PT (resprouters with heat-tolerant propagules) and 17% was R+PS (resprouters with heat-stimulated propagules). The remaining 2% (one species) was classified as R+P−, showing heat-sensitive seeds. Conclusions: Resprouting is the main post-fire regeneration strategy in Cerrado open savannas, while fire-stimulated germination, although possible, is less common in comparison to the frequency in other fire-prone ecosystems. However, in Cerrado open savannas, heat tolerance is an important trait that enables germination when favorable conditions arise.