Your best buds are worth protecting: Variation in bud protection in a fire-prone cerrado system

Abstract

Species growing in fire-prone savannas usually persist by resprouting from their buds. In this study, we evaluated how various persistence traits allow bud protection for improved survival in fire-prone ecosystems. Using an integrative morphological and macroanatomical approach, we analysed how woody plants protect their buds. We tested bud protection at the community level and evaluated: (a) how bud protection changes along a fire frequency gradient, (b) if it differs between shrubs and trees and (c) whether the level of bud protection is related to post-fire responses of 28 woody savanna species. A mix of traits involving bud protection may enable woody species persistence in fire-prone ecosystems. Savanna species better protected their buds than forest species by developing bark and trichomes that allowed resprouting after fire. Regarding growth forms, shrub species capable of resprouting above-ground had their buds better protected than trees. Bud protection is not only linked with their position to the bark, but also with the presence of trichomes. Profuse trichomes covering buds were related to savanna species. Some species with no bud protection by bark but with trichomes covering their buds were able to resprout after fire. The presence of accessory buds is also a trait more related to savannas, possibly influencing the resprouting after fire as they are better protected and increase the bud bank. Finally, different persistence traits interact with one another to better protect the buds, requiring a detailed screening of the traits to assess species responses to fire. Synthesis. During fire, species have their aerial biomass consumed by the flames. To be able to resprout new branches and persist in the environment, they must have well-protected buds. In this study, we evaluated different ways that woody species protect their buds and related them with their resprouting strategy after fire. We investigated the protection by the bark, the presence of trichomes and accessory buds. By studying the woody community in a gradient of savannas and forests we found that buds can be protected by bark, trichomes or soil. Species can present a mix of these traits and strategies, which enhances their resprouting after fire. A free Plain Language Summary can be found within the Supporting Information of this article.