Flowering and fruiting show phenological complementarity in both trees and non-trees in mosaic-burnt floodable savanna

The homogenization of fire regimes in a landscape may imply a temporal reduction in the availability of re-sources, such as flowers and fruits, which affect the fauna, as well as ecosystem services. We hypothesized that maintaining mosaic burning regimes, and thereby pyrodiversity, can diversify phenological patterns, ensuring year-round availability of flowers and fruits. Here we monitored open grassy tropical savanna phenology under different historical fire frequencies and fire seasons in a highly heterogeneous landscape in an Indigenous Ter-ritory in Brazil. We evaluated phenological patterns of tree and non-tree plants through monthly surveys over three years. These two life forms responded differently to climate and photoperiod variables and to fire. Different fire regimes led to a continuous availability of flowers and fruits, due to the complementarity between tree and non-tree phenologies. Late-season fires are supposed to be more devastating, but we did not detect a significant reduction in flower and fruit production, especially under moderate fire frequency. However, late burning in patches under high frequency resulted in a low availability of ripe fruits in trees. The fruiting of non-tree plants in patches under low fire frequency and early burning ensure ripe fruit, when there are practically no trees fruiting in the entire landscape. We conclude that maintaining a seasonal fire mosaic should be prioritized over historical fire regimes, which lead to homogenization. Fire management is best conducted between the end of the rainy season and the beginning of the dry season, when the risk of burning fertile plants is lower.

Automated summary

The homogenization of fire regimes can lead to a temporal reduction in the availability of resources, affecting fauna and ecosystem services. Maintaining mosaic burning regimes can diversify phenological patterns, ensuring year-round availability of flowers and fruits. Different fire regimes had differential effects on tree and non-tree phenologies, and moderate fire frequency did not significantly reduce flower and fruit production. However, late burning in high-frequency patches resulted in a low availability of ripe fruits in trees, while fruiting of non-tree plants in low fire frequency patches and early burning ensured a continuous supply of ripe fruits throughout the year.