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

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

Floristic units and their predictors unveiled in part of the Atlantic Forest hotspot: implications for conservation planning

ABSTRACT We submitted tree species occurrence and geoclimatic data from 59 sites in a river basin in the Atlantic Forest of southeastern Brazil to ordination, ANOVA, and cluster analyses with the goals of investigating the causes of phytogeographic patterns and determining whether the six recognized subregions represent distinct floristic units. We found that both climate and space were significantly (p ≤ 0.05) important in the explanation of phytogeographic patterns. Floristic variations follow thermal gradients linked to elevation in both coastal and inland subregions. A gradient of precipitation seasonality was found to be related to floristic variation up to 100 km inland from the ocean. The temperature of the warmest quarter and the precipitation during the coldest quarter were the main predictors. The subregions Sandy Coastal Plain, Coastal Lowland, Coastal Highland, and Central Depression were recognized as distinct floristic units. Significant differences were not found between the Inland Highland and the Espinhaço Range, indicating that these subregions should compose a single floristic unit encompassing all interior highlands. Because of their ecological peculiarities, the ferric outcrops within the Espinhaço Range may constitute a special unit. The floristic units proposed here will provide important information for wiser conservation planning in the Atlantic Forest hotspot

Florística e estrutura da vegetação arbórea de um fragmento de floresta semidecedual às margens do reservatório da usina hidrelétrica Dona Rita (Itambé do Mato Dentro, MG) Floristic composition and structure of the tree community of a fragment of the submontane semideciduous forest in Itambé do Mato Dentro Minas Gerais State, south-eastern Brazil

Realizou-se o levantamento florístico e fitossociológico da comunidade arbórea de um fragmento de Floresta Estacionai Semidecidual Sub-Montana localizado às margens do reservatório da usina hidrelétrica Dona Rita, situado na Fazenda Camarinha, em Itambé do Mato Dentro, MG, na bacia do rio Doce (19º26'S, 43º 14' W, altitude entre 610 e 630m). Todos os indivíduos com diâmetro do caule à altura do solo > 5,0cm (exceto lianas) encontrados em 35 parcelas de 15xl5m (0,78ha) foram identificados, medidos e tiveram sua altura estimada (também foram coletados indivíduos que se apresentavam com estruturas reprodutivas, fora das parcelas). Foram estimados para cada espécie os seguintes parâmetros: densidade por área, freqüência absoluta, dominância absoluta e índice de valor de importância (IVI). Também foram calculados o índice de diversidade de Shannon e a equabilidade correspondente, o índice de similaridade de Jaccard e as distâncias euclidianas quadradas entre esta floresta e outras do alto e médio Rio Grande, baixo Paranaíba e alto São Francisco. Nas parcelas foram amostrados 2.430 indivíduos. Identificou-se 216 espécies (15 fora das parcelas) pertencentes a 50 famílias e 144 gêneros. Destacam-se pelo IVI as famílias Euphorbiaceae, Myrtaceae e Caesalpiniaceae e as espécies Apuleia leiocarpa, Pera glabrata, Licania hypoleuca e Mabeafistulifera. Comparada com algumas florestas ciliares do Estado, a floresta de Itambé do Mato Dentro se assemelha mais com a do alto Rio Grande (ambas localizadas em regiões sob influência da Mata Atlântica), muito embora as espécies mais importantes não sejam as mesmas. Em termos pedológicos a floresta de Itambé apresenta os solos mais intemperizados, lixiviados e profundos, apesar de seu relevo íngreme, devido ao material constitutivo dos mesmos ter sofrido intenso processo de alteração anterior ao atual ciclo pedogênico.<br>A floristic and phytosociological survey of the tree commnunity was carried out in a fragment of sub-montane semideciduous forest located on the margin of the Dona Rita Hydroelectric Reservoir, municipality of Itambé do Mato Dentro, State of Minas Gerais, south-eastern Brazil (19º26'S, 43º14'W, 610-630m of altitude). All individuals with a stem diameter at the base, of dbt > 5cm (lianas excepted) found in thirty five 15x15m quadrats, were identified, measured (dbt) and had their height estimated (individuals found outside quadrats with reproductive structure were also collected). The following phytosociological parameters were calculated for all species: density per area, absolute frequency, absolute dominance calculated from the basal area, and importance value. The Shannon diversity index and the corresponding evenness were calculated. Jaccard's similarity indices and euclidian distances were also calculated among the studied forest and other forests surveyed in the following regions of Minas Gerais State: Upper and Mid Rio Grande, Lower Rio Paranaiba and Upper Rio São Francisco. A total of 2,430 individuals were recorded in the sample area. These belonged to 50 families, 144 genera and 216 species. The following families produced the highest importance values: Euphorbiaceae, Myrtaceae and Caesalpiniaceae. The most important species were Apuleia leiocarpa, Pera glab rata, Licania hypoleuca, and Mabeafistulifera. A comparison with the other areas indicated that the forest of Itambé do Mato Dentro is more similar to those of the Upper Rio Grande which are all under a stronger floristic influence of the Atlantic Forest, although the most important species are not the same. The soils of the area are deeper, highly weathered and leached, despite the strongly sloping topography because they had gone through an intense process of alteration prior to the present pedogenetic cycle

Dinâmica da estrutura fitossociológica da regeneração natural em sub-bosque de Mimosa scabrella Bentham em área minerada, em Poços de Caldas, MG Phytosociology structure dynamics of natural regeneration in understory of Mimosa scabrella Bentham in mined area, Poços de Caldas, Brazil

Como estratégia de reabilitação de área minerada foram realizados, no ano agrícola 1982/1983, hidrossemeadura de gramíneas e leguminosa e o plantio puro de Mimosa scabrella Bentham em Poços de Caldas, MG. Em 1997 foi implantado um conjunto de 19 parcelas permanentes de 50 m² nessa área, para caracterização inicial do processo de regeneração natural. Em 2000, foi realizado o segundo inventário nas parcelas, para caracterização do processo de dinâmica da regeneração natural, que é o objeto deste trabalho. O processo de dinâmica da regeneração natural foi caracterizado mediante análises quantitativas e qualitativas da composição florística e da estrutura horizontal e vertical. O povoamento florestal do Retiro-Branco está sobre intensa atividade de estruturação, caracterizando o estágio inicial do processo de sucessão. O declínio do povoamento puro de Mimosa escabrella está modificando a ordem anteriormente estabelecida para o processo de sucessão da área, provocando a diversificação de condições de sítio e, assim, selecionando a ocupação deste em função dos grupos ecológicos, sendo as espécies pioneiras as mais favorecidas. As espécies secundárias são as de maior dominância nas maiores classes de altura e de diâmetro, sendo as principais responsáveis pela edificação do estrato superior, em especial a espécie Miconia sellowiana. As espécies que apresentaram melhor desempenho na colonização e estruturação da regeneração natural do Retiro-Branco, nos dois inventários, foram Miconia sellowiana, Psychotria sessilis, Leandra melastomoides, Clethra scabra, Myrsine umbellata, Miconia pepericarpa, Tibouchina candolleana, Cordia superba, Cestrum amictum, Alchornea triplinervia, Casearia sylvestris, Blepharocalyx salicifolius, Myrcia rostrata e Schinus terebinthifolius, sendo indicadas como espécies para uso nos programas de reabilitação de áreas mineradas em condições semelhantes sobre a estratégia sucessional.<br>As part of mine rehabilitation strategy, herbaceous species hydroseeding and Mimosa scabrella Bentham seedling planting was carried out in 1982/1983 the Retiro-Branco bauxite mine site. In 1997, 19 sample plots of 50m² were established for initial characterization of the natural regeneration process. In 2000, a second inventory was performed in those same sample plots, to characterize natural regeneration dynamics. This process was characterized by means of quantitative and qualitative analyses of floristic composition and horizontal and vertical structures. The forest succession at Retiro-Branco was found to be undergoing intense restructuring activity, characterizing initial stage of succession. The decline of Mimosa scabrella pure stands is modifying the successional order that previously occurred in this area, causing diversity in site conditions. Occupation of these sites occurs by ecological groups, pioneer species being favored in the process. Secondary species, especially Miconia sellowiana, dominate the classes with greatest height and diameter, and are the most responsible for construction of the superior stratum. Species which presented the best performance in colonization and structuring of natural regeneration at Retiro-Branco for both inventories were Miconia sellowiana, Psychotria sessilis, Leandra melastomoides, Clethra scabra, Myrsine umbellata, Miconia pepericarpa, Tibouchina candolleana, Cordia superba, Cestrum amictum, Alchornea triplinervia, Casearia sylvestris, Blepharocalyx salicifolius, Myrcia rostrata and Schinus terebinthifolius. These are indicated as promising species for rehabilitation programs of mined areas with similar conditions of sucessional strategy