The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species-less diverse than the North American tree flora-accounts for half of the world's most diverse tree community

The extent to which pre-Columbian societies altered Amazonian landscapes is hotly debated. We performed a basin-wide analysis of pre-Columbian impacts on Amazonian forests by overlaying known archaeological sites in Amazonia with the distributions and abundances of 85 woody species domesticated by pre-Columbian peoples. Domesticated species are five times more likely than nondomesticated species to be hyperdominant. Across the basin, the relative abundance and richness of domesticated species increase in forests on and around archaeological sites. In southwestern and eastern Amazonia, distance to archaeological sites strongly influences the relative abundance and richness of domesticated species. Our analyses indicate that modern tree communities in Amazonia are structured to an important extent by a long history of plant domestication by Amazonian peoples

AimThe accurate mapping of forest carbon stocks is essential for understanding the global carbon cycle, for assessing emissions from deforestation, and for rational land-use planning. Remote sensing (RS) is currently the key tool for this purpose, but RS does not estimate vegetation biomass directly, and thus may miss significant spatial variations in forest structure. We test the stated accuracy of pantropical carbon maps using a large independent field dataset.LocationTropical forests of the Amazon basin. The permanent archive of the field plot data can be accessed at: http://dx.doi.org/10.5521/FORESTPLOTS.NET/2014_1MethodsTwo recent pantropical RS maps of vegetation carbon are compared to a unique ground-plot dataset, involving tree measurements in 413 large inventory plots located in nine countries. The RS maps were compared directly to field plots, and kriging of the field data was used to allow area-based comparisons.ResultsThe two RS carbon maps fail to capture the main gradient in Amazon forest carbon detected using 413 ground plots, from the densely wooded tall forests of the north-east, to the light-wooded, shorter forests of the south-west. The differences between plots and RS maps far exceed the uncertainties given in these studies, with whole regions over- or under-estimated by > 25%, whereas regional uncertainties for the maps were reported to be < 5%.Main conclusionsPantropical biomass maps are widely used by governments and by projects aiming to reduce deforestation using carbon offsets, but may have significant regional biases. Carbon-mapping techniques must be revised to account for the known ecological variation in tree wood density and allometry to create maps suitable for carbon accounting. The use of single relationships between tree canopy height and above-ground biomass inevitably yields large, spatially correlated errors. This presents a significant challenge to both the forest conservation and remote sensing communities, because neither wood density nor species assemblages can be reliably mapped from space.

Analyses of forest loss and protected areas suggest that 36 to 57% of Amazonian tree flora may qualify as “globally threatened.”

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.

RESUMO -(Estrutura e composição florística de quatro formações vegetais de restinga no complexo lagunar, with an area of 4,800 ha, was studied. A 25 ha (2,500 x 100m) transect was set up from the sea inland, sampling being carried out from 1995 to 1997. The four physiognomic unities that occur in the area were studied and, using the Cover Value Index, the most characteristic species in each formation were determined. 1) Beach Grass Formation: Remirea maritima, Ipomoea imperati, Sporobolus virginicus and Chamaecyse thymifolia; 2) Beach Grass and Shrub Formation: Schinus terebinthifolius, Eugenia sulcata, Pilosocereus arrabidae and Cereus fernambucensis; 3) Clusia Formation: Pera glabrata, Eugenia sulcata, Sideroxylon obtusifolium and Scutia arenicola; 4) Restinga Forest Formation: Maytenus obtusifolia, Pera glabrata, Protium heptaphyllum and Coccoloba alnifolia. The floristic similarity between the study area and other sites in the Rio de Janeiro and Espírito Santo States were lower than 41%. Geografic proximity was not related to the highest similarities found, supporting the hypothesis about extensive floristic variation within restinga vegetations.

-(Phytosociological studies in a remnant lowland forest on tertiary "tabuleiros" in the north Rio de Janeiro State). The forests on Barreiras formations are located in fragmented areas extending from the Rio Grande do Norte State to north of Rio de Janeiro State. In the north of Rio de Janeiro State, the "Mata do Carvão" (1053 ha) is the largest remaining fragment. This study describes the structure and floristic composition of a remnant forest on tertiary tabuleiros and its main aim was to compare this forest with other "tabuleiro" and Atlantic forest remnants in the region. To carry out the inventory, four plots of 50 x 50 m were allocated in a selected area without vestiges of logging activities or fire. All trees ≥ 10 cm DBH were sampled and numbered with aluminium tags. Dead trees were measured but not tagged. A total of 564 trees was sampled being distributed within 34 families. The families with higher number of species were Leguminosae (18), Myrtaceae (8), and Euphorbiaceae (6). The most abundant families were Rutaceae (189), Leguminosae (97) and Euphorbiaceae (47). The species with higher cover index values were Metrodorea brevifolia, Paratecoma peroba and Pseudopiptadenia contorta. Although the "Mata do Carvão" showed lower tree diversity (H' = 3.21) than those found for other semi-deciduous seasonal forests, it has a high species similarity between the tabuleiro forests of South Bahia and North of Espírito Santo. In the "Mata do Carvão", the occurrence of rare species at risk of extinction (e.g. Paratecoma peroba) was observed. Furthermore, these are new occurrences for the Rio de Janeiro State (Centrolobium sclerophyllum and Polygala pulcherrima).RESUMO -(Fitossociologia de um remanescente de mata sobre tabuleiros no norte do Estado do Rio de Janeiro). As formações florestais sobre tabuleiros terciários ocorrem hoje na forma de pequenos fragmentos desde o Rio Grande do Norte até o Rio de Janeiro. No norte fluminense, a Mata do Carvão (1.053 ha) é o maior remanescente. Este trabalho descreve a estrutura e a composição florística desta mata, tendo por objetivo compará-la com outras matas da região. Foram estabelecidas quatro parcelas de 50 m x 50 m em uma área selecionada, sem vestígios de corte e de fogo. Todas as árvores com DAP ≥ 10 cm foram amostradas e plaqueadas. Árvores mortas foram medidas mas não plaqueadas. Um total de 564 árvores foram amostradas. Foram encontradas 34 famílias, sendo as de maior número de espécies Leguminosae (18), Myrtaceae (8) e Euphorbiaceae (6). As famílias mais abundantes foram Rutaceae (189), Leguminosae (97) e Euphorbiaceae (47). As espécies com maior índice de valor de cobertura (IVC) foram Metrodorea brevifolia, Paratecoma peroba e Pseudopiptadenia contorta. Embora a Mata do Carvão tenha uma diversidade (H' = 3,21 nats) menor que outras matas estacionais semidecíduas (ex. mata de tabuleiro de Linhares), ela possui uma alta similaridade de espécies arbóreas com as matas de tabuleiro do sul da Bahia e do norte do Espírito Santo. Na Mata do Carvão foi observad...

Aim The Brazilian Atlantic forest covers c. 10% of its original extent, and some areas are still being logged. Although several ecological studies in Atlantic forest have been published over the past two to three decades, there has been little research on forest dynamics and there is a particular lack of information on the effects of disturbance. The aim of the present study was to assess the impact of selective logging on forest structure, floristic composition soil nutrients, litterfall and litter layer in a seasonally dry Atlantic forest.Location The Mata do Carvão is located in the Guaxindiba Ecological Reserve in São Francisco do ltabapoana district (21°24¢ S, 41°04¢ W), Rio de Janeiro, Brazil.Methods Four plots (50 · 50 m) were set up in 1995 in each of two stands: unlogged and logged. In each plot, all trees ‡ 10 cm d.b.h. were enumerated, identified and measured. Vouchers were lodged at UENF Herbarium. Five surface soil samples were collected in each plot in the dry season (in October 1995). Litterfall was collected in eight traps (0.50 m 2 ) in each plot over a year from The litter layer was sampled in eight quadrats (0.25 m 2 ) in each plot in the dry and wet seasons. Soils were air-dried, sieved, and chemically analysed. The litter was dried (80°C), sorted into six fractions, weighed and bulked samples analysed for nutrients. ResultsForest stands did not differ in stem density and total basal area, with a total of 1137 individuals sampled in 1996 (564 unlogged and 573 logged), and a total basal area of 15 m 2 (unlogged) and 13.0 m 2 (logged). However, unlogged stands had more large trees ( ‡ 30 cm in d.b.h.) and greater mean canopy height. Among the families, Rutaceae and Leguminosae were the most abundant families in both sites, although the Rutaceae had a higher density in unlogged and Leguminosae in the logged stand. The species diversity index was similar between stands. Late-successional species, such as Metrodorea nigra var. brevifolia and Paratecoma peroba, were less abundant in the logged stand. Selective logging did not affect nutrient concentrations in the soil or in the litter. However, quantities of the nutrients in the total litterfall and in the leaf litterfall and litter layer were higher in unlogged than in logged stands, mainly as a result of fallen M. nigra leaves. Metrodorea nigra was considered a key species in the nutrients dynamics in Carvão forest.Main conclusions Despite the fact that effects on tree diversity and soil nutrients were not clear, selective logging in this Atlantic forest altered canopy structure, increased the relative abundance of some early-secondary species and decreased the litter input and stock of nutrients. Detailed information on the influence of logging on the distribution and structure of plant populations and in nutrient processes is fundamental for a sustainable logging system to be developed.