André Maciel Silva-Sene

Recent evidence indicates that Brazilian forests are shifting from persistent carbon sinks to emerging carbon sources, with important implications for the global climate. To investigate this trend, we analyse long-term census data from 49 forest sites spanning southeast and southern Brazil, including tropical and subtropical forests. We examine above-ground carbon dynamics and its relationship with tree diversity and functional traits that are tightly linked with species’ carbon processing and storage capacities. Our findings reveal a long-term trend of taxonomic, functional and phylogenetic homogenisation and a decline in the forests’ above-ground carbon sink. Specifically, homogeneous forests have lower carbon losses, whilst forests with more conservative species are associated with greater carbon gains and lower carbon losses. Overall, our study establishes a baseline to understand and predict the above-ground carbon sink in the face of ongoing climate change in this region.

Floodplains provide fertile soils and essential ecosystem services, including water purification and nutrient cycling, yet they face intense human pressure. We investigated the diversity, structure, and functional traits of a tropical floodplain across five eco-units: Marginal Levee, Lower Terrace, Higher Terrace, Lower Plain and Higher Plain. NMDS analysis showed that species composition is strongly shaped by the flooding regime, with Inga vera dominant in most eco-units and Machaerium villosum prevailing in the Higher Plain. The Higher Plain also exhibited the highest aboveground biomass (AGB) and structural heterogeneity. Diameter class distributions differed significantly among eco-units, and terraces showed a higher proportion of sprouting individuals, reflecting adaptive responses to water stress. GLMM models indicated that species adopt conservative strategies under stress, producing thicker, more durable leaves, while stem density and specific stem density respond to soil fertility. These results reveal how hydrological and edaphic factors govern community structure and functional strategies, providing essential insights for the conservation and management of floodplain forests under increasing anthropogenic and climatic pressures.

Seasonal floodplain forests are unique but threatened ecosystems. Trees in these ecosystems have adapted to extreme conditions of excess water and drought. However, what water sources these trees use is not fully known and therefore the vulnerability of floodplain forests to changes in the hydrological cycle remains poorly understood. In this study, we sampled different water sources (precipitation, streamflow, groundwater, soil water at different depths) and vegetation across six floodplain forests in the Rio Grande and São Francisco basins in southeastern Brazil during four campaigns (two dry and two wet seasons). We used water stable isotope data to investigate the sources for root water uptake. There was no consistent dry‐to‐wet season variation in the isotopic composition of soil water, but soil water reflected the isotopic signature of the wet season’s precipitation and overbank flow. There was a very large variability in the isotopic composition of xylem water, but no consistent pattern across the floodplains, or between tree species. Mixing model analyses suggest that for the floodplains in the Rio Grande basin, soil water was the main source of root water uptake during the wet season (64% ± 17) but not during the dry season (43% ± 17), when streamflow and groundwater were the main sources. In the São Francisco basin, soil water was the main source of root water uptake (60% ± 17 and 72% ± 15 for the wet and dry seasons, respectively). However, the uncertainties are large due to the similarity in the isotopic composition of potential water sources.

Tree growth and longevity trade-offs fundamentally shape the terrestrial carbon balance. Yet, we lack a unified understanding of how such trade-offs vary across the world’s forests. By mapping life history traits for a wide range of species across the Americas, we reveal considerable variation in life expectancies from 10 centimeters in diameter (ranging from 1.3 to 3195 years) and show that the pace of life for trees can be accurately classified into four demographic functional types. We found emergent patterns in the strength of trade-offs between growth and longevity across a temperature gradient. Furthermore, we show that the diversity of life history traits varies predictably across forest biomes, giving rise to a positive relationship between trait diversity and productivity. Our pan-latitudinal assessment provides new insights into the demographic mechanisms that govern the carbon turnover rate across forest biomes.

Floodplains are one of the most threatened ecosystems. Even though the vegetation composition in floodplain forests is expected to reflect the variation in groundwater levels and flood duration and frequency, there is little field data on the inundation dynamics (e.g., the variability in flood duration and flood frequency), especially for the understudied seasonally dry tropics. This limits our understanding of these ecosystems and the mechanisms that cause the flooding. We, therefore, investigated six floodplain forests in the state of Minas Gerais in Brazil for 1.5 years (two wet seasons): Capivari, Jacaré, and Aiuruoca in the Rio Grande basin, and Jequitaí, Verde Grande, and Carinhanha in the São Francisco basin. These locations span a range of climates (humid subtropical to seasonal tropical) and biomes (Atlantic forest to Caatinga). At each location, we continuously measured water levels in five geomorphologically distinct eco‐units: marginal levee, lower terrace, higher terrace, lower plain, and higher plain, providing a unique hydrological dataset for these understudied regions. The levees and terraces were flooded for longer periods than the plains. Inundation of the terraces lasted around 40 days per year. The levees in the Rio Grande basin were flooded for shorter durations. In the São Francisco basin, the flooding of the levees lasted longer and the water level regime of the levees was more similar to that of the terraces. In the Rio Grande basin, flooding was most likely caused by rising groundwater levels (i.e., “flow pulse”) and flood pulses that caused overbank flooding. In the São Francisco basin, inundation was most likely caused by overbank flooding (i.e., “flood pulse”). These findings highlight the large variation in inundation dynamics across floodplain forests and are relevant to predict the impacts of changes in the flood regime due to climate change and other anthropogenic changes on floodplain forest functioning.

Seasonally Dry Tropical Forests experience pronounced precipitation seasonality, intense solar radiation, and high temperatures, which often translate into high levels of deciduousness during the dry season. In these environments, deciduous species coexist with some evergreen species that are able to maintain their canopy leaves throughout the dry season. To understand the strategies behind this behavior, we analyzed leaf anatomical traits of 13 individuals of Sarcomphalus joazeiro during both the wet and dry seasons in a seasonal deciduous forest. We hypothesized that wet-season leaves would differ anatomically and functionally from dry-season leaves. Specifically, we expected wet-season leaves to show a more acquisitive resource-use strategy compared to dry-season leaves, which we expected to be more conservative. We assessed the effects of season and climatic variables on 25 leaf anatomical traits using generalized linear mixed models (LMM). Leaf traits varied between the wet and dry seasons and interacted with climatic variables, which together suggest that S. joazeiro produces season-specific leaf cohorts. This adaptation allows the species to adjust to the contrasting conditions of light intensity, temperature, and evaporative demand in each season.

Erythroxylum is common in the Brazilian Cerrado. Species from this genus have ecological, pharmacological and popular medical importance. Based on this information, the aims of this study was to perform a descriptive and quantitative morphoanatomical study of Erythroxylum tortuosum leaves present in two environments: cerrado sensu stricto and campo rupestre. To carry out these studies, 24 fully developed leaves were collected and fixed from individuals across both environments. For the quantitative anatomy study, the following measurements were made: leaf area, length, width and mass; stomatal density; polar and equatorial diameter of the stomata; thickness of the leaf blade, mesophyll, epidermis and cuticles on the adaxial and abaxial surfaces; and thickness of the spongy and palisade parenchyma; specific leaf area, leaf mass area and foliar tissue density. This species shows a bald and uniseriate epidermis when viewed in cross section. Stomata are paracytic and occur only on abaxial surfaces. The mesophyll is dorsiventral type, with a dense vascular system, and the vascular bundle is collateral type. The general pattern of the veins is pinnate camptodrome and brochidodrome, with dense veins and pseudosecondary ribs. Significant differences were found for almost all analysed variables, suggesting that different environmental conditions may influence plant development.

Byrsonima coccolobifolia Kunth. (Malpighiaceae) é citada como planta apícola, forrageira, produtora de frutos comestíveis e como planta medicinal, podendo ser utilizada como diurética (uso interno, em infusão) a partir das cascas dos caules e dos frutos. O objetivo deste trabalho foi realizar um estudo quali-quantitativo das características anatômicas da folhas desta espécie que ocorre em áreas de cerrado e campo rupestre. As observações anatômicas foram realizadas em folhas de material fresco ou fixado, tratadas segundo metodologias usuais em anatomia vegetal. Foram observadas as seguintes características: epidermes do pecíolo e da lâmina foliar uniestratificadas; estômatos do tipo paracítico presentes somente na face abaxial da folha; mesofilo com parênquima paliçádico de uma só camada de células; parênquima lacunoso com sete a nove camadas celulares com formas irregulares e tamanhos variados; idioblastos cristalíferos, observados em todos os parênquimas do pecíolo e lâmina foliar; feixes vasculares, do tipo colateral; colênquima observado, subepidermicamente, no pecíolo e nervuras de maior porte, nas duas faces; o padrão geral de nervação da espécie é pinado, camptódromo, broquidódromo. As análises micromorfométricas revelaram diferenças significativas em todos os itens quantitativos analisados, sendo as médias mais elevadas encontradas nas folhas das plantas crescendo no cerrado. Isto sugere que a influência de fatores ambientais pode ter modulado respostas morfológicas nas plantas, visto que o tipo e distribuição qualitativa dos tecidos não sofreram alterações nos dois ambientes.