Mapping density, diversity and species-richness of the Amazon tree flora.

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution.

Unraveling Amazon tree community assembly using Maximum Information Entropy: a quantitative analysis of tropical forest ecology.

In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important constraints via predictions using least biased probability distributions. We apply it to over two thousand hectares of Amazonian tree inventories across seven forest types and thirteen functional traits, representing major global axes of plant strategies. Results show that constraints formed by regional relative abundances of genera explain eight times more of local relative abundances than constraints based on directional selection for specific functional traits, although the latter does show clear signals of environmental dependency. These results provide a quantitative insight by inference from large-scale data using cross-disciplinary methods, furthering our understanding of ecological dynamics.

Biased-corrected richness estimates for the Amazonian tree flora.

Amazonian forests are extraordinarily diverse, but the estimated species richness is very much debated. Here, we apply an ensemble of parametric estimators and a novel technique that includes conspecific spatial aggregation to an extended database of forest plots with up-to-date taxonomy. We show that the species abundance distribution of Amazonia is best approximated by a logseries with aggregated individuals, where aggregation increases with rarity. By averaging several methods to estimate total richness, we confirm that over 15,000 tree species are expected to occur in Amazonia. We also show that using ten times the number of plots would result in an increase to just ~50% of those 15,000 estimated species. To get a more complete sample of all tree species, rigorous field campaigns may be needed but the number of trees in Amazonia will remain an estimate for years to come.

Species Distribution Modelling: Contrasting presence-only models with plot abundance data.

Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and MaxEnt predictions relates to a spatial abundance model, based on a large plot dataset for Amazonian tree species, using inverse distance weighting (IDW). We also propose a new pipeline to deal with inconsistencies in NHCs and to limit the area of occupancy of the species. We found a significant but weak positive relationship between the distribution of NHCs and IDW for 66% of the species. The relationship between SDMs and IDW was also significant but weakly positive for 95% of the species, and sensitivity for both analyses was high. Furthermore, the pipeline removed half of the NHCs records. Presence-only SDM applications should consider this limitation, especially for large biodiversity assessments projects, when they are automatically generated without subsequent checking. Our pipeline provides a conservative estimate of a species' area of occupancy, within an area slightly larger than its extent of occurrence, compatible to e.g. IUCN red list assessments.

Estimating the global conservation status of more than 15,000 Amazonian tree species.

Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict that most of the world's >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century.

First record of the chemical composition of essential oil of Piper bellidifolium, Piper durilignum, Piper acutilimbum and Piper consanguineum from the Brazilian Amazon forest / Primeiro registro da composição química de óleos essenciais de Piper bellidifolium, Piper durilignum, Piper acutilimbum e Piperconsanguineumda Floresta Amazônica no Brasil

Piper bellidifolium, Piper durilignum, Piper acutilimbum and Piper consanguineum are bushes that occur in the Amazon and are morphologically similar. With the aim of analyzing the chemical profile of the volatile constituents of these species, essential oils from the leaves were obtained through steam distillation and analyzed using gas chromatography-flame ionization detection (GC-FID) and gas chromatograph coupled to a mass spectrometer (GC-MS). The chemical analysis enabled the identification of 95 compounds representing 96.3 ± 0.6% of the P. bellidifolium oil, 95.5 ± 0.71% of the P. durilignum oil, 98.0 ± 1.0% of the P. acutilimbum oil and 96.1 ± 2.1% of the P. consanguineum oil. Although sesquiterpenes were the predominant chemical class in the oils of the four species, qualitative and quantitative differences were found in their chemical composition. The major constituents were (E)-nerolidol (20.3 ± 0.4%) in the P. bellidifolium oil, germacrene D (11.1 ± 0.3%) in the P. durilignum oil, and -eudesmol in both the P. consanguineum (18.6 ± 0.5%) and P. acutilimbum (7.5 ± 0.4%) oils. Despite their morphological similarity, a principal component analysis (PCA) of the GC-MS data clearly separated the four species according to the chemical profile of the essential oil extracted from their leaves.

Piper bellidifolium, Piper durilignum, Piper acutilimbum e Piper consanguineum são arbustos que ocorrem na Amazônia e são morfologicamente similares. Com o intuito de analisar o perfil químico dos constituintes voláteis dessas espécies, óleos essenciais das folhas foram obtidos por hidrodestilação e analisados por cromatografia gasosa - detector por ionização de chama (CG-FID) e cromatografia gasosa acoplada a espectrometria de massa (CG-EM). A análise química permitiu identificar 95 compostos, representando 96.3 ± 0.6% do óleo de P. bellidifolium; 95.5 ± 0.71% de P. durilignum; 98.0 ± 1.0% de P. acutilimbum e 96.1 ± 2.1% de P. consanguineum. Apesar dos óleos das quatro espécies terem sesquiterpeno como classe química predominante, diferenças qualitativas e quantitativas em sua composição química foram observadas. Os principais componentes encontrados foram: (E)-nerolidol (20.3 ± 0.4%) em P. bellidifolium; germacreno D (11.1 ± 0.3%) em P. durilignum; e -eudesmol nos óleos de P. consanguineum (18.6 ± 0.5%) e P. acutilimbum (7.5 ± 0.4%). Apesar da similaridade morfológica entre as espécies, uma análise de componentes principais (PCA) dos dados de CG-EM claramente separou as quatro espécies quanto ao perfil químico do óleo essencial extríado de suas folhas.

A new species of Dichaea (Orchidaceae) for northern Brazil / Uma nova espécie de Dichaea (Orchidaceae) para o norte do Brasil

Dichaea is the largest genus of the subtribe Zygopetalinae and holds it's the highest species diversity in South America. Therefore, this study aims to describe a new species of Dichaea, which occurs in northern Brazil, Dichaea bragae Valsko, Krahl & Holanda. The new species was collected in the north of Manaus in an area of ombrophilous forest and flowered when cultivated. The epithet honors Dr. Pedro Ivo Soares Braga (in memoriam), orchidologist who conducted several studies in the Brazilian Amazon. This new species show a affinity with Dichaea tenuis C. Schweinf., however it is differentiated both vegetatively and on labellum morphology.

Dichaea é o maior gênero da subtribo Zygopetalinae e possui sua maior diversidade de espécies na América do Sul. Diante disto, este trabalho teve o objetivo de descrever uma nova espécie de Dichaea ocorrente na região norte do Brasil, Dichaea bragae Valsko, Krahl & Holanda. A nova espécie foi coleta ao norte de Manaus em área de floresta ombrófila e floresceu em cultivo. O epíteto é em homenagem ao Dr. Pedro Ivo Soares Braga (in memorian), orquidólogo que realizou vários estudos na Amazônia brasileira. A nova espécie possui afinidade com espécies de Dichaea seção Dichaeopsis, contudo são diferenciadas vegetativamente e na morfologia do labelo.