The strengths and weaknesses of species distribution models in biome delimitation

This is the final published version, also available from Frontiers via the DOI in this record.Aim: The aim was to test whether species distribution models (SDMs) can reproduce major macroecological patterns in a species-rich, tropical region and provide recommendations for using SDMs in areas with sparse biotic inventory data. Location: North-east Brazil, including Minas Gerais. Time period: Present. Major taxa studied: Flowering plants. Methods: Species composition estimates derived from stacked SDMs (s-SDMs) were compared with data from 1,506 inventories of 933 woody plant species from north-east Brazil. Both datasets were used in hierarchical clustering analyses to delimit floristic units that correspond to biomes. The ability of s-SDMs to predict the identity, functional composition and floristic composition of biomes was compared across geographical and environmental space. Results: The s-SDMs and inventory data both resolved four major biomes that largely corresponded in terms of their distribution, floristics and function. The s-SDMs proved excellent at identifying broad-scale biomes and their function, but misassigned many individual sites in complex savanna–forest mosaics. Main conclusions: Our results show that s-SDMs have a unique role to play in describing macroecological patterns in areas lacking inventory data and for poorly known taxa. s-SDMs accurately predict floristic and functional macroecological patterns but struggle in areas where non-climatic factors, such as fire or soil, play key roles in governing distributions.Natural Environment Research Council (NERC)Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorConselho Nacional de Desenvolvimento Científico e TecnológicoRoyal Societ

Dynamics of the shrub-tree component of an alluvial gallery forest on the Poços de Caldas Plateau, MG State, Brazil

A dinâmica do componente arbustivo-arbóreo foi investigada em uma floresta de galeria aluvial em Poços de Caldas, Minas Gerais, entre 1998 e 2005. Os objetivos principais foram: investigar se as taxas de dinâmica das florestas de galeria aluviais são inferiores a outras formações florestais ripárias tropicais e, se as inundações periódicas geram variação espacial na dinâmica no sentido Rio-Borda. A amostragem foi composta de 101 parcelas de 10 × 10 m, distribuídas em 5 blocos ao longo de, aproximadamente, 8 km da floresta do Rio das Antas. Cada bloco foi dividido em 3 setores (Rio, Interior e Borda). Comparativamente a outras florestas tropicais ripárias, a floresta em estudo apresentou taxas de dinâmica mais lentas. A Borda foi mais dinâmica que os outros setores, provavelmente devido à maior incidência luminosa, propiciando ambiente adequado às espécies de ciclo de vida curto.The dynamics of the shrub-tree component was investigated in an alluvial gallery forest in Poços de Caldas, Minas Gerais, from 1998 to 2005. The main objective of this study was to verify if the rates of the dynamics of the alluvial gallery forests are less than other tropical riparian forest formations. Seasonal flooding was also studied to see if it generates a spatial variation in the dynamics of going from the stream side towards the forest border. The sample consisted of 101, 10×10-meter plots that were distributed in five blocks extending approximately 8 km along the Antas River's forest. Each block was divided into three sectors (stream side, forest interior, and forest edge). Compared with other tropical forests, especially the riparian ones, this forest showed lower rates in terms of structural alterations. The forest edge is more dynamic, mainly due to the greater amount of sunlight, which supplies an adequate environment for species with a short life cycle

An estimate of the number of tropical tree species

The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher’s alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼40,000 and ∼53,000, i.e. at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼19,000–25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼4,500–6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa

Classifica\ue7\ue3o das fitofisionomias da Am\ue9rica do Sul cisandina tropical e subtropical: proposta de um novo sistema — pr\ue1tico e flex\uedvel — ou uma inje\ue7\ue3o a mais de caos?

Volume: 60Start Page: 237End Page: 25

Classificação das fitofisionomias da América do Sul cisandina tropical e subtropical: proposta de um novo sistema - prático e flexível - ou uma injeção a mais de caos?

RESUMO O presente trabalho propõe um novo sistema de nomenclatura e classificação fisionômico-ecológica para a vegetação da América do Sul tropical e subtropical a leste dos Andes. A formulação do sistema procura desempenhar o papel de ferramenta da linguagem técnica e científica, mas também resistiu a trazer mais uma visão pessoal sobre as variações da vegetação. Desta maneira, o foco foi para a comunicação pela via da articulação prática e flexível de um conjunto de símbolos. Esta abordagem contrasta com aquelas que associam a precisão da linguagem a uma série de definições rígidas. Por outro lado, a formulação procurou também evitar excessos de liberdade para não perder o alvo prático em meio à anarquia. Foi por esse motivo que a proposta utilizou como ponto de partida o sistema mais familiar ao meio acadêmico: a classificação do IBGE para a vegetação brasileira. Entre as propostas de melhoria destacam-se as possibilidades de combinar símbolos para atender a uma ampla variação da escala espacial e respectivos níveis de detalhamento e de escolher apenas os símbolos com maior poder de descrição em cada caso

Tree population and community dynamics in a Brazilian tropical semideciduous forest

ABSTRACT – (Tree population and community dynamics in a Brazilian tropical semideciduous forest). The dynamics of the tree community and 30 tree populations were examined in an area of tropical semideciduous forest located on the margin of the Rio Grande, SE Brazil, based on surveys done in 1990 and 1997 in three 0.18 ha plots. The main purpose was to assess whether variations in dynamics were related to topography and the effects of a catastrophic flood in 1992. Rates of mortality and recruitment of trees and gain and loss of basal area in two topographic sites, lower (flooded) and upper (non-flooded), were obtained. Projected trajectories of mean and accelerated growth in diameter were obtained for each species. In both topographic sites, mortality rates surpassed recruitment rates, gain rates of basal area surpassed loss rates, and size distributions changed, with declining proportions of smaller trees. These overall changes were possibly related to increased underground water supply after the 1992 flood as well as to a c. 250-year-old process of primary succession on abandoned gold mines. Possible effects of the 1992 flood showed up in the higher proportions of dead trees in the flooded sites and faster growth rates in the flood-free sites. Species of different regeneration guilds showed particular trends with respect to their demographic changes and diameter growth patterns. Nevertheless, patterns of population dynamics differed between topographic sites for only two species. Key words- forest dynamics, tree community dynamics, tree growth, tree population dynamics, tropical semideciduous forest RESUMO – (Dinâmica da comunidade e de populações arbóreas em uma floresta tropical semidecídua). A dinâmica da comunidade arbórea e de 30 populações das espécies constituintes foi investigada em uma área de floresta tropical semidecídua situada na margem do Rio Grande, em Bom Sucesso (MG), com base em inventários conduzidos em 1990 e 1997 em três parcelas de 0,1