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 resources, 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 Territory 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.

Laguncularia racemosa leaves indicate the presence of potentially toxic elements in mangroves.

Brazilian mangroves have been severely impacted by metallurgical, petrochemical, pyrometallurgical smelters and other industrial activities. In Rio de Janeiro, mangroves are part of the Atlantic Rainforest now under the stress of high levels of industrial waste. Therefore, this work aimed to detect potentially toxic elements (PTEs) by evaluating the leaves of Laguncularia racemosa (L.) Gaertn. f. collected from three mangroves with different levels of pollution. To gain further insight toward an accurate diagnosis of the effects of anthropogenic pollution on mangrove stands, we evaluated leaf epicuticular wax composition, as well as morphological and anatomical traits. Samples were analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES), gas chromatography (GC) and microscopy. Results revealed variation in the contents of PTEs among the three mangroves from lowest to highest concentration, as follows: Al (0.30-0.73), Pb (0.095-0.325) and Zn (0.25-0.30) mg/kg. Zn was detected in sclerenchyma tissues. Leaf epicuticular wax contained more than 50% of triterpenes, in particular, the pentacyclic triterpenes lupeol (41.61-55.63%) and ß-amyrin (8.81-16.35%). Such high concentrations promote the increase in leaf permeability to salts and PTEs. Micromorphology of leaf epicuticular wax in L. racemosa also varied among the three evaluated sites, especially around stomatal openings, but no harmful changes were noted. L. racemosa plays a key role in the rich diversity of mangrove ecosystems. As such, this species could, by the presence of PTEs in its leaves, be a suitable biomonitor of toxic substances in coastal environments of the world and used accordingly in strategies designed for eco-sustainable technologies.