One sixth of Amazonian tree diversity is dependent on river floodplains

Amazonia's floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region's floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon's tree diversity and its function.Naturali

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

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Does neutral theory explain community composition in the Guiana shield forests?

Recent years have seen a fierce debate about the causes of beta-diversity, the change in species composition over landscapes, in tropical rainforests. The introduction of neutral models has spurred this debate, by assuming that species composition changes randomly over landscapes with dispersal limitation as the driving ecological process. In this study the interaction between local and regional diversity of trees is investigated. We inventoried 61 1-ha plots in forests on brown and white sands, and on bauxite mountains in Guyana and Suriname. These data combined with earlier data led to the first biogeographical study on a species level involving 156 forest plots ranging from Venezuela to French Guiana. Forest composition changed dramatically between forest types, and at geographical distances. In general, forest composition followed geological patterns in the Guianas. Differences in plant attributes between the forest groups revealed a spectrum in covariation. On the one end of this spectrum a high dominance of trees with large seeds in dry fruits was combined with high wood densities in several forest types. On the other end a high dominance of trees and species with smaller seeds in fleshy fruits was combined with relatively low community averaged wood density. This spectrum could reflect different colonizing strategies of trees in the forest types, and could have an effect on potential dispersers. With neutral-like dynamical community models, different hypotheses on the low diversity of the white sand forest were evaluated. Forests on white and brown sands draw their species from different regional species pools. We provide strong evidence that asymmetric environmental filtering and a lower regional diversity (possibly due to the smaller size of the white sand area) could influence the lower diversity found in white sand forests compared with neighboring brown sand forests. White sand forests were not necessarily more dispersal limited than brown sand forests. Still within the white sand forests apparent changes in species abundance patterns occurred along geographical distances. Thus, we showed that a gradient in beta-diversity could occur in forests under similar climatic and soil conditions. The conservation value in terms of tree diversity of three bauxite mountains in Northeastern Suriname, was evaluated by placing 23 1-ha plots on the plateaus, slopes, and in the lowlands. These mountains are all destined for open-pit mining for aluminum ore, and may constitute a rare and endangered landscape type. Habitat type (e.g. the plateaus) explained more floristic similarity between plots than geographical distance. The plateaus also had the highest tree alpha-diversity currently found in Suriname. However, forest composition on the plateaus was also partly a random draw of species from the lowlands, and each of the mountains had its own specific species composition. Forests in the Guianas show evident differences in tree responses and composition, yielding little support for a neutral view. Most patterns are caused by small sets of common species that may dominate the forests, especially where the alpha-diversity of the forests is low. Striking biogeograpical patterns in the rainforests of the Guianas however remain unexplained by (current) environmental conditions

Towards a carbon balance for forests in Suriname

Currently Suriname is developing systems for Monitoring, Reporting and Verification (MRV) for Reducing Emissions from Deforestation and Forest Degradation (REDD). The goal of the study reported in this report is to support the development of an adequate MRV system for forest carbon in Suriname, with a focus on quantification of monitoring and reporting carbon stocks from field sampling. Based on available existing field data, allometric functions and expansion factors aboveground biomass and carbon stocks are assessed for a number of forest types. Using the data from a long-term logging experiment at the CELOS-Kabo site changes in carbon stocks were quantified over time and under different intensities of selective logging. A review of carbon budget estimates across the Amazon were used to put the results for Suriname in a broader perspective. Finally an overview of methods to quantify and monitor forest carbon stocks at different scales are presented and discusse

Towards a global list of accepted species III. Independence and stakeholder inclusion

A global consensus list of the world’s species must be based on the best available taxonomic research, and its contents should not be biased towards certain political or social aims. At the same time, users of any global list must be involved or consulted in its establishment to ensure that the list meets their needs. This paper argues that while these two desiderata— independence and inclusion—might seem to be in conflict, they are in fact compatible. More precisely, it suggests the roles taxonomists and users could play in establishing and maintaining a global consensus list to make sure that this list is both inclusive and independent

Principles for creating a single authoritative list of the world's species

Copyright: © 2020 Garnett et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Lists of species underpin many fields of human endeavour, but there are currently no universally accepted principles for deciding which biological species should be accepted when there are alternative taxonomic treatments (and, by extension, which scientific names should be applied to those species). As improvements in information technology make it easier to communicate, access, and aggregate biodiversity information, there is a need for a framework that helps taxonomists and the users of taxonomy decide which taxa and names should be used by society whilst continuing to encourage taxonomic research that leads to new species discoveries, new knowledge of species relationships, and the refinement of existing species concepts. Here, we present 10 principles that can underpin such a governance framework, namely (i) the species list must be based on science and free from nontaxonomic considerations and interference, (ii) governance of the species list must aim for community support and use, (iii) all decisions about list composition must be transparent, (iv) the governance of validated lists of species is separate from the governance of the names of taxa, (v) governance of lists of accepted species must not constrain academic freedom, (vi) the set of criteria considered sufficient to recognise species boundaries may appropriately vary between different taxonomic groups but should be consistent when possible, (vii) a global list must balance conflicting needs for currency and stability by having archived versions, (viii) contributors need appropriate recognition, (ix) list content should be traceable, and (x) a global listing process needs both to encompass global diversity and to accommodate local knowledge of that diversity. We conclude by outlining issues that must be resolved if such a system of taxonomic list governance and a unified list of accepted scientific names generated are to be universally adopted

As espécies de tauari (Lecythidaceae) em florestas de terra firme da Amazônia: padrões de distribuição geográfica, abundâncias e implicações para a conservação "Tauari" species (Lecythidaceae) in non-flooded Amazon forest: patterns of geographic distribution, abundance, and implications for conservation

Conhecer a distribuição de uma espécie é essencial para o conhecimento de sua ecologia e conservação. Neste estudo, foram levantadas a composição, a abundância, a estrutura diamétrica e a distribuição geográfica das espécies de tauari (Lecythidaceae), um dos grupos de árvores mais explorados na Amazônia. Foram utilizados dados de herbários para definir a área de distribuição das espécies e inventários em seis áreas do bioma (totalizando 401,25 ha) para estimar abundâncias e estruturas diamétricas. Das 14 espécies ocorrentes na Amazônia, nove foram encontradas nos inventários. Couratari guianensis apresentou a maior área de distribuição contínua, porém sempre com densidades baixas. Couratari stellata apresentou a segunda maior área de distribuição, porém disjunta e, em geral, com densidades altas. Cariniana micrantha e Couratari multiflora apresentaram ampla distribuição e densidades variáveis, enquanto a maioria das demais espécies mostrou distribuição regional ou endêmica, e densidades menores que um indivíduo por hectare. A classificação das espécies em relação ao tipo de raridade divergiu daquelas descritas para Couratari guianensis e C. multiflora. Os resultados ressaltam a escassez de dados sobre espécies madeireiras nas regiões mais desmatadas da Amazônia, a necessidade do levantamento da abundância populacional local e regional para a melhor caracterização do seu padrão de distribuição e fornecem bases para a revisão das categorias e critérios de ameaças das espécies de Couratari na lista vermelha da IUCN.<br>Understanding the range of a species is essential to understanding its ecology and conservation. In this study we collected data on the composition, abundance, diametric structure, and geographic distribution of "tauari" species (Lecythidaceae), which are among the most exploited timber trees of the Amazonian forest. We used herbarium data to define the areas of distribution and inventories of 401.25 ha from six areas of Amazonia to list species for estimating abundance and diametric structure. Of the 14 species that occur in the biome, nine were sampled in the inventories. Couratari guianensis had the largest continuous area of distribution, but always at low densities. Couratari stellata had the second largest distribution, but it was discontinuous and usually at high densities. Cariniana micrantha and Couratari multiflora had wide distributions and variable densities, whereas most of the other species showed regional or restricted ranges and densities below one individual per hectare. The classification of species according to rarity type diverged from that described for Couratari guianensis and C. multiflora. These results point out the lack of data for timber species in the most deforested regions of Amazonia, the need for local and regional abundance investigation for better understanding of distribution patterns, and to provide support for reviewing the categories and criteria of threats of Couratari species on the IUCN Red List

The biogeography of the Amazonian tree flora

We describe the geographical variation in tree species composition across Amazonian forests and show how environmental conditions are associated with species turnover. Our analyses are based on 2023 forest inventory plots (1 ha) that provide abundance data for a total of 5188 tree species. Within-plot species composition reflected both local environmental conditions (especially soil nutrients and hydrology) and geographical regions. A broader-scale view of species turnover was obtained by interpolating the relative tree species abundances over Amazonia into 47,441 0.1-degree grid cells. Two main dimensions of spatial change in tree species composition were identified. The first was a gradient between western Amazonia at the Andean forelands (with young geology and relatively nutrient-rich soils) and central–eastern Amazonia associated with the Guiana and Brazilian Shields (with more ancient geology and poor soils). The second gradient was between the wet forests of the northwest and the drier forests in southern Amazonia. Isolines linking cells of similar composition crossed major Amazonian rivers, suggesting that tree species distributions are not limited by rivers. Even though some areas of relatively sharp species turnover were identified, mostly the tree species composition changed gradually over large extents, which does not support delimiting clear discrete biogeographic regions within Amazonia