Diversity, composition and biomass of native vascular plants regenerating under Acacia mangium Will. plantations in northern Amazonia

It is imperative that studies can be developed to assess the role of homogeneous tree plantations in biodiversity conservation and the ability to store atmospheric carbon. This study aimed to evaluate the effects of Acacia mangium Will. plantations established in areas originally occupied by savanna (locally termed “lavrado”) on the establishment success of vascular plants, by analyzing three attributes of the community—diversity, composition and biomass. All plants with base diameter ≥ 1 cm were measured in 28 0.05-ha plots (11 plots allocated in natural areas of “lavrado” and 17 under A. mangium plantations). Species diversity was much higher in A. mangium plantation than in the natural areas of “lavrado”. There was a clear floristic differentiation between A. mangium and “lavrado”, with high density of forest species and low density of “lavrado” species growing under A. mangium plantations. “Lavrado” plots presented high floristic similarity, but plots under A. mangium plantations were far less similar, indicating a more heterogeneous vegetation. Biomass of vascular plants in A. mangium plantations was about one-fifth of that found in natural “lavrado” sites, but in “lavrado” 92.6% of the total biomass was allocated in only two species, whereas in A. mangium plantation two species comprised only 43% of the total biomass. In A. mangium plantation, species classified as forest species and typical “lavrado” species accounted for 72.8% and 27.2% of total biomass, respectively. Our results showed that A. mangium plantations resulted in high alpha and beta plant diversity due to the invasion of alien forest species. Also, biomass of “lavrado” species in plantations was smaller and species relative abundances completely different from natural “lavrados”. Therefore, we conclude that forest plantations established in savannas cannot be used to meet conservationist purposes. © 2019, Botanical Society of Sao Paulo

Taxa de cruzamento de Couratari multiflora (J.Smith) Eyma (Lecythidaceae), uma espécie arbórea tropical de baixa densidade da Amazônia central

A multilocus mixed-mating model was used to evaluate the mating system of a population of Couratari multiflora, an emergent tree species found in low densities (1 individual/10 ha) in lowland forests of central Amazonia. We surveyed and observed phenologically 41 trees in an area of 400 ha. From these, only four mother trees were analyzed here because few of them set fruits, which also suffered high predation. No difference was observed between the population multilocus outcrossing rate (t mp = 0.953 ± 0.040) and the average single locus rate (t sp = 0.968 ± 0.132). The four mother trees were highly outcrossed (t m ~ 1). Two out of five loci showed departures from the Hardy-Weinberg Equilibrium (HWE) expectations, and the same results occurred with the mixed-mating model. Besides the low number of trees analyzed, the proportion of loci in HWE suggests random mating in the population. However, the pollen pool was heterogeneous among families, probably due to both the small sample number and the flowering of trees at different times of the flowering season. Reproductive phenology of the population and the results presented here suggest, at least for part of the population, a long-distance pollen movement, around 1,000 m.Foi utilizado um modelo de cruzamento misto multilocos para analisar o sistema de cruzamento de uma população de Couratari multiflora, espécie arbórea emergente encontrada em baixas densidades (1 indivíduo/10 ha) nas florestas de "terra firme" da Amazônia central. Inventariamos e observamos fenologicamente 41 árvores em uma área de 400 ha. Dessas, somente quatro árvores-mãe foram analisadas, pois poucas árvores produziram frutos, os quais também sofreram alta predação. Não foi observada diferença entre a taxa de cruzamento multilocos (t mp = 0,953 ± 0,040) e a taxa média de loco único (t sp = 0,968 ± 0,132). As quatro árvores-mãe apresentaram alta taxa de cruzamento (t m ~ 1). Dois dos cinco locos analisados mostraram desvios das expectativas do Equilíbrio de Hardy-Weinberg (EHW), e os mesmos resultados ocorreram para o modelo misto de cruzamento. Apesar do baixo número de árvores analisadas, a alta proporção de locos em EHW sugere que a população tenha um sistema de cruzamento aleatório. Entretanto, o conjunto polínico foi heterogêneo entre famílias, provavelmente pelo pequeno número e florescimento das árvores analisadas em diferentes fases da estação de florescimento. A fenologia reprodutiva da população e os resultados apresentados neste estudo sugerem que ao menos parte da população cruza via movimento de pólen de longa distância, em torno de 1.000 m

Soil controls biomass and dynamics of an Amazonian forest through the shifting of species and traits

The effects of soil on tree species composition and trait distributions in tropical forest, and how these interactions affect tree biomass and dynamics, are poorly understood because variation in soil is confounded with variation in climate over large areas. We excluded confounding due to climate by studying variation among 72 1-ha plots within 64 km2, and minimized within-plot variation in soil and stand properties by using long narrow plots oriented along altitudinal contours in Reserva Ducke, Central Amazonia, Brazil. Soil variation caused shifts in tree species composition, which determined stand-level wood density. Soil clay content, cation exchange capacity, plot mean wood density and one-dimensional ordination of tree species composition explained about 40% of variation in tree biomass, 24% of variation in tree mortality and 18% of variation in coarse wood production. As pioneer species were not abundant, lower biomass and higher mortality on sandy soils is a consequence of dominance of species with low to medium wood density adapted to waterlogged and nutrient-poor sandy soils. Therefore, mesoscale variation in biomass and dynamics is caused by co-occurrence of species with similar traits in different parts of the edaphic gradient. Identification of mechanisms controlling tree biomass and dynamics in Amazonian forest will require better understanding of tree–soil physiologic interactions. © 2016, Botanical Society of Sao Paulo

Organic matter contents and characteristics in hydromorphic soils of the State de Espirito Santo

Os teores e as características da matéria orgânica do solo (MOS) são resultados das taxas de produção e incorporação, decomposição ou alteração e mineralização, de acordo com as condições do ambiente. Nos solos hidromórficos, a dinâmica da MOS é influenciada pelo déficit de oxigênio, o que diminui a taxa de decomposição e gera produtos diferenciados em relação aos solos bem drenados. O presente trabalho teve por objetivo determinar os teores e características da matéria orgânica do solo em três diferentes localidades do Estado do Espírito Santo. Foram realizadas determinações de C orgânico total (COT) por três métodos, além de fracionamento das substâncias húmicas (SH), com determinação de teores das frações humina (FHU), ácidos húmicos (FAH) e ácidos fúlvicos (FAF), e determinações de matéria orgânica leve (MOL) e resíduos mínimos. Os resultados mostraram altos teores de C orgânico para a maioria dos horizontes superficiais dos perfis estudados, com ocorrência de material de constituição orgânica; altos valores na relação SH/COT e baixos valores para EA/FHU, indicando a fração humina como a predominante entre os compartimentos da MOS; maior mobilidade da fração ácidos fúlvicos, expressa por teores relativamente maiores em subsuperfície; e altos teores de MOL, indicando incipiente humificação, em razão do hidromorfismo.Soil organic matter (SOM) contents and characteristics are results of production, incorporation, decomposition, alteration, and mineralization rates, according to environmental conditions. In hydromorphic soils, SOM dynamics are regulated by O2 deficit, lowering the decomposition rates and producing substances different from those in well-drained soils. This article aimed to determine SOM contents and characteristics at three locations in the State of Espirito Santo, Brazil. Total organic carbon (TOC) was quantified by three methods, besides partitioning humic substances (HS) and determining the humin (FHU), humic (FAH) and fulvic acid (FAF) fraction contents, light organic matter (LOM), and minimum residues. Results indicated high organic C in most surface horizons and material with organic constitution. High values of SH/TOC and low values of EA/FHU ratios indicated the humin fraction as the most important fraction of SOM compartments. The mobility of fulvic acid fraction was higher than of the others, expressed by relatively higher contents in the subsurface. The high LOM content indicated a low humification degree, due to the hydromorphic conditions

AS PLANTAS DO BIOMA CAATINGA COM POTENCIAL NEUROPROTETOR: UMA REVISÃO INTEGRATIVA

O Brasil é considerado um dos países de maior biodiversidade do planeta, tendo a caatinga como um bioma exclusivamente brasileiro. As plantas usadas na terapêutica local são de constante interesse da etnobotânica, através do conhecimento sobre o uso e aplicação da biodiversidade. Estudos recentes apontam para algumas novas propostas terapêuticas no tratamento de doenças neurológicas, dentre elas, destaca-se a terapia com células derivadas de medula óssea e o tratamento com flavonóides de ação antioxidante e anti-inflamatória. Esses compostos estão presentes na maioria das plantas com potenciais antioxidante e anti-inflamatório. O presente estudo teve como objetivo investigar o estudo de propriedades neuroprotetoras em plantas nativas da caatinga nas universidades brasileiras, através dos trabalhos de conclusões acadêmicos. A pesquisa é uma revisão de literatura, onde serão reunidos trabalhos de conclusão acadêmicos relacionados à investigação de propriedades neuroprotetoras em plantas da caatinga. Os trabalhos (Monografias, Dissertações e Teses) foram encontrados a partir de repositórios acadêmicos indexados na base eletrônica do Google Acadêmico. Esse levantamento de dados possibilitou um conhecimento acerca das plantas que possam apresentar um potencial medicinal neuroprotetor do bioma caatinga que ainda não foram estudadas com tanta eficiência, entre essas plantas temos as seguintes famílias: Anacardiaceae, Lamiaceae, Fabaceae, sendo a família de maior destaque, Apocynaceae, Convolvulaceae, Rutaceae, Asteraceae, Cucurbitaceae. Diante do presente estudo destaca-se a descoberta de propriedades neuroprotetoras nas plantas da caatinga e sua aplicação na terapia de doenças neurológicas, porém as evidências e estudos ainda são poucos

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors

Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types