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Aims We aimed at disentangling the effects of spatial distance, current and past environmental dissimilarity, and their combinations on tree community taxonomic and phylogenetic turnover by addressing the following questions: (i) Is tree community taxonomic and phylogenetic turnover related to the indirect effects of spatial distance via environmental dissimilarity? (ii) Does tree community taxonomic and phylogenetic turnover respond to paleoclimate (Last Glacial Maximum and Mid-Holocene)? Methods The study was carried out in 14 Atlantic rainforest sites in Brazil (20.4 ha sampled) containing 615 tree species from 83 plant families. We obtained plot-level geographic coordinates and soil variables and site-level bioclimatic variables in the current, Mid-Holocene and Last Glacial Maximum. We used structural equation models with a distance-based approach to (i) test the direct effects of spatial distance and environmental dissimilarity and (ii) test the indirect effects of spatial distance via environmental dissimilarity on taxonomic (Bray–Curtis distance) and phylogenetic turnover (Comdist and Comdistnt distances). Important Findings Our results suggest a weak indirect effect of spatial distance via environmental dissimilarity on taxonomic and phylogenetic turnover. Tree community turnover was driven by the direct effects of neutral, niche-based and historical processes. Thus, we inferred that the paleoclimate (historical processes) promoted the selection of the clades that gave rise to the current flora, while spatial distances (neutral processes) limited the dispersal range of species from the regional pool and environmental conditions (niche-based processes) locally selected the taxa that are able to persist.

Discrete thresholds of structural or functional decline of a vegetation type are not readily apparent, as a vegetation type can slowly decline leading to transformations in its species composition and weakened or altered functions. However, forest monitoring can be used to assess changes in ecological functions in community structure and functional and phylogenetic composition of species. This study evaluated the existence of temporal variations in the functional and phylogenetic composition of a tree community, the occurrence of heterogeneity in the behavior of phylogenetic and functional variations, and how this possible heterogeneity influences the functional and phylogenetic variations under the aspect of environmental variations and by demographic ecological processes. Results detected quantitative and qualitative changes throughout the community, such as colonization, local extinctions, in demography and biomass, and increased evolutionary distinction, lower wood density species and phylogenetic clustering. These results have shown us that the natural changes of a community should not be underestimated, because the disappearance of a community can not only occur by the direct elimination of vegetation, but can be incremental with gradual changes in its functional characteristics and species composition, transforming itself into a new community with a new combination of species and new functions., Los umbrales discretos de deterioro estructural o funcional de un tipo de vegetación no son fácilmente aparentes, ya que un tipo de vegetación puede disminuir lentamente, lo que lleva a transformaciones en la composición de sus especies y funciones debilitadas o alteradas. Sin embargo, las observaciones pueden usarse para evaluar los cambios en las funciones ecológicas antes de que esto ocurra a través de la estructura comunitaria y la composición funcional y filogenética de las especies. Este estudio evaluó la existencia de variaciones temporales en la composición funcional y filogenética de una comunidad arbórea; la ocurrencia de heterogeneidad en el comportamiento de variaciones filogenéticas y funcionales; y cómo esta posible heterogeneidad influye en las variaciones funcionales y filogenéticas bajo el aspecto de variaciones ambientales y por procesos demográficos ecológicos. Los resultados en la detección de cambios cuantitativos y cualitativos en toda la comunidad con la colonización y las extinciones locales en la comunidad, las diferencias demográficas y de biomasa, la distinción evolutiva aumentada, las especies de menor densidad de madera y el agrupamiento filogenético. Los resultados han demostrado que los cambios naturales de una comunidad no deben subestimarse, porque la desaparición de una comunidad no solo puede ocurrir por la eliminación directa de la vegetación, sino que puede ser incremental con cambios graduales en sus características funcionales y composición de especies, transformando en una nueva comunidad con una nueva combinación de especies y nuevas funciones.

A new species of Pseudobombax (Bombacoideae, Malvaceae) is described from the Furados, Caatingas Domain, Brazil. The new species is morphologically similar to Pseudobombax simplicifolium but differs by the obovate, elliptic, depressed obovate or orbicular leaflets, the presence of branched trichomes on terminal branches, leaf primordia, petioles, adaxial and abaxial surfaces of leaflets, pedicel, bracteoles, and outer surface of the calyx, lepidote ovary, and the subglobose to ovoid, and spotted seeds.

Tropical forests have played an important role as a carbon sink over time. However, the carbon dynamics of Brazilian non-Amazon tropical forests are still not well understood. Here, we used data from 32 tropical seasonal forest sites, monitored from 1987 to 2020 (mean site monitoring length, ~15 years) to investigate their long-term trends in carbon stocks and sinks. Our results highlight a long-term decline in the net carbon sink (0.13 Mg C ha-1 year-1) caused by decreasing carbon gains (2.6% by year) and increasing carbon losses (3.4% by year). The driest and warmest sites are experiencing the most severe carbon sink decline and have already moved from carbon sinks to carbon sources. Because of the importance of the terrestrial carbon sink for the global climate, policies are needed to mitigate the emission of greenhouse gases and to restore and protect tropical seasonal forests.

Resprouting is an ecological strategy widely adopted by trees in response to different restrictive factors, in which the stems can be emitted at different heights of the tree. Although the patterns of resprouting height are already known in response to some restrictive factors (such as fire), their occurrence is not well elucidated in non-fire prone dry environments where continuous resource restriction may stimulate resprouting. Here, we assessed the general ecological dominance of resprouting trees in the community and the ecological dominance of trees resprouting at different heights in response to environmental restrictions in a tropical dry forest (TDF). We used multi-stemmed trees as a proxy for resprouting in response to the local restrictive factors. Our hypotheses were: i) resprouting trees have greater ecological dominance (more trees and stems and higher biomass) in more restrictive plots; ii) the ecological dominance of lower-height resprouting trees is greater in more restrictive plots, while the dominance of upper-height resprouting trees is greater in less restrictive plots. For this, we used a dataset of 27 TDF plots where we measured and identified the trees that met the inclusion criterion (3 cm of diameter at breast height) and collected soil samples to gather data on environmental restriction. Multi-stemmed trees were classified according to the height of additional-stem emission (below-ground, ground-level, and above-ground), considering the bottom-most stem originating from the main stem. We then evaluated whether the ecological dominance of resprouting trees and trees with different resprouting heights varied significantly in response to environmental restrictiveness, and patterns of species composition in the height categories. We found a greater dominance of resprouting trees in more restrictive environments, with lower-height resprouting trees dominating the most restrictive plots (two hypotheses confirmed). This finding may be associated with physiological mechanisms of drought response because resprouting height is directly associated with the level of damage inflicted on the internal structure of trees. We also found that the species varied in their ability for stem emission at different heights, whereby the most plastic species were more dominant compared to those with just one height of emission. This finding indicates that different restrictive factors can produce similar resprouting expressions, reinforcing the need to advance the knowledge on the importance of resprouting in TDF.

Forest dynamics are driven by a myriad of factors and link directly to ecosystem services. The dynamics of the highly degraded Brazilian Atlantic Forest (AF) hotspot is mostly driven by its anthropogenic context. Currently, most of the AF region is composed of small disturbed secondary forest fragments that have received partial or full environmental protection with recent environmental norms. Such protection prevents further disturbances and consequently shifts the course of forest dynamics and ecosystem services in AF. Here, we assess long-term forest dynamics trends of a small secondary AF fragment to test the hypothesis that disturbed AF fragments are reaching advanced successional stages. We used a unique dataset of 126 permanent subplots (totaling 5.04 ha) monitored for 30 years (8 inventories between 1987 and 2017) of a disturbed secondary AF fragment (6.35 ha) that has been fully protected since 1986. In each inventory, we measured all living trees with a diameter at breast height (DBH) ≥ 5 cm and counted survivors, recruits and dead individuals between intervals. We monitored the temporal trends of (i) structural variables (biomass, tree density and species richness), (ii) functional composition (wood density and maximum potential size), (iii) and species dominance. Our results indicate that, now under full protection, the fragment is shifting towards a late successional stage: we observed increasing biomass, decreasing tree density (self-thinning) and increasing abundance of late-successional species with conservative strategies. Species richness and dominant species composition were stable throughout the monitoring period, suggesting an absence of substantial changes in community assembly. These results underscore the role played by small secondary AF fragments in ecosystem service provision (e.g., carbon uptake and shelter for biodiversity) and point to their forest dynamics trends.

This work reports the isolation of the sesquiterpene lactone 15-deoxygoyazensolide from the stems of Minasia alpestris and the evaluation of its antimicrobial activity against the following oral pathogens: Enterococcus faecalis, Streptococcus salivarius, Streptococcus sobrinus, Streptococcus mutans, Streptococcus mitis, Streptococcus sanguinis, and Lactobacillus casei. Despite the cytotoxicity and genotoxicity of other sesquiterpene lactones of the furanoheliangolide-type, our results revealed that this compound exhibits low antibacterial activity against the evaluated oral pathogens; however, an interesting selectivity against E. faecalis (minimum inhibitory concentration [MIC]=40 µg mL(-1)) and S. sobrinus (MIC=60 µg mL(-1)) was observed.