Disentangling the veil line for Brazilian biodiversity: An overview from two long-term research programs reveals huge gaps in ecological data reporting.

The lack of synthesized information regarding biodiversity is a major problem among researchers, leading to a pervasive cycle where ecologists make field campaigns to collect information that already exists and yet has not been made available for a broader audience. This problem leads to long-lasting effects in public policies such as spending money multiple times to conduct similar studies in the same area. We aim to identify this knowledge gap by synthesizing information available regarding two Brazilian long-term biodiversity programs and the metadata generated by them. Using a unique dataset containing 1904 metadata, we identified patterns of metadata distribution and intensity of research conducted in Brazil, as well as where we should concentrate research efforts in the next decades. We found that the majority of metadata were about vertebrates, followed by plants, invertebrates, and fungi. Caatinga was the biome with least metadata, and that there's still a lack of information regarding all biomes in Brazil, with none of them being sufficiently sampled. We hope that these results will have implications for broader conservation and management guiding, as well as to funding allocation programs.

Giants of the Amazon: How does environmental variation drive the diversity patterns of large trees?

For more than three decades, major efforts in sampling and analyzing tree diversity in South America have focused almost exclusively on trees with stems of at least 10 and 2.5 cm diameter, showing highest species diversity in the wetter western and northern Amazon forests. By contrast, little attention has been paid to patterns and drivers of diversity in the largest canopy and emergent trees, which is surprising given these have dominant ecological functions. Here, we use a machine learning approach to quantify the importance of environmental factors and apply it to generate spatial predictions of the species diversity of all trees (dbh ≥ 10 cm) and for very large trees (dbh ≥ 70 cm) using data from 243 forest plots (108,450 trees and 2832 species) distributed across different forest types and biogeographic regions of the Brazilian Amazon. The diversity of large trees and of all trees was significantly associated with three environmental factors, but in contrasting ways across regions and forest types. Environmental variables associated with disturbances, for example, the lightning flash rate and wind speed, as well as the fraction of photosynthetically active radiation, tend to govern the diversity of large trees. Upland rainforests in the Guiana Shield and Roraima regions had a high diversity of large trees. By contrast, variables associated with resources tend to govern tree diversity in general. Places such as the province of Imeri and the northern portion of the province of Madeira stand out for their high diversity of species in general. Climatic and topographic stability and functional adaptation mechanisms promote ideal conditions for species diversity. Finally, we mapped general patterns of tree species diversity in the Brazilian Amazon, which differ substantially depending on size class.

RAPELD: a modification of the Gentry method for biodiversity surveys in long-term ecological research sites

Este estudo descreve uma modificação do método de parcelas de 0.1 ha desenvolvido por Gentry, que nós adaptamos para sítios de pesquisa ecológica de longa-duração na Amazônia brasileira. Nosso objetivo foi desenvolver um método que fosse apropriado para pesquisas ecológicas de longa-duração (componente PELD), mas que permitissem inventários rápidos para avaliação da complementaridade biótica e planejamento do uso da terra na Amazônia (componente RAP). A filosofia por trás do método é a de maximizar a probabilidade de amostrar adequadamente as comunidades biológicas, para o que são necessárias áreas amostrais grandes, e ao mesmo tempo minimizar a variação nos fatores abióticos que afetam estas comunidades, o que requer amostragem de áreas pequenas. Para conseguir isto, as parcelas são longas e estreitas, com seu maior eixo orientado ao longo das curvas de nível do terreno. Este desenho minimiza a variação interna de topografia e solo em cada parcela, e permite o uso destas variáveis como preditoras das distribuições de espécies. O desenho pode ser usado para vários taxa e estágios de vida, ajustando a largura da parcela ou distribuindo sub-amostras ao longo da parcela. As parcelas são distribuídas sistematicamente em uma grade de trilhas, que é usada para amostrar taxa que não podem ser amostrados em parcelas pequenas. Cada grade de trilhas e parcelas constitui um sítio de pesquisa. A distribuição sistemática de parcelas na paisagem permite estimativas não tendenciosas da distribuição, abundância e biomassa das espécies em cada sítio, e comparações biogeográficas entre sítios. Os custos de implementação são moderados, considerando a grande produção gerada pelos estudos integrados.