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Recent debates on the number of plant species in the vast lowland rain forests of the Amazon have been based largely on model estimates, neglecting published checklists based on verified voucher data. Here we collate taxonomically verified checklists to present a list of seed plant species from lowland Amazon rain forests. Our list comprises 14,003 species, of which 6,727 are trees. These figures are similar to estimates derived from nonparametric ecological models, but they contrast strongly with predictions of much higher tree diversity derived from parametric models. Based on the known proportion of tree species in neotropical lowland rain forest communities as measured in complete plot censuses, and on overall estimates of seed plant diversity in Brazil and in the neotropics in general, it is more likely that tree diversity in the Amazon is closer to the lower estimates derived from nonparametric models. Much remains unknown about Amazonian plant diversity, but this taxonomically verified dataset provides a valid starting point for macroecological and evolutionary studies aimed at understanding the origin, evolution, and ecology of the exceptional biodiversity of Amazonian forests.
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Biodiversidad , Bases de Datos Factuales , Plantas/clasificación , Bosque Lluvioso , BrasilRESUMEN
The world's largest mineral iron province, Serra dos Carajás, is home to an open vegetation known as canga, found on top of isolated outcrops rising out of the Amazon rainforest. Over one thousand vascular plants species have been recorded in these canga sites, including 38 edaphic endemics. A new survey adds to our investigation of biogeographic relationships between sixteen canga outcrops and the effect of the distance between site pairs on the number of shared species, regional species turnover and species distribution patterns. Plant collecting expeditions to the westernmost site, the Serra de Campos of São Félix do Xingu (SFX), were carried out followed by the identification of all collected specimens and the creation of a species database, built to perform biogeographical analyses. Floristic relationships among the sites were investigated regarding their similarity, using multivariate analyses. The correlation between canga areas and species richness was tested, as well as the geographical distance between pairs of outcrops and their shared species. Vascular plants at SFX total 254 species including 17 edaphic endemics. All canga sites are grouped with 25% of minimum similarity, and the SFX falls within a large subgroup of outcrops. The total species number shared between site pairs does not change significantly with geographical distance but is positively correlated with the area of each outcrop. Meanwhile, shared endemic species numbers between site pairs decline when geographical distance increases, possibly imposed by the barrier of the rainforest. Our data suggest higher shared similarity between the largest and species-richest sites as opposed to geographically nearby sites, and provide useful insight for drafting conservation and compensation measures for canga locations. The size of the canga outcrops is associated to higher floristic diversity but connectivity among islands also plays a role in their similarity.
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ABSTRACT Leaf anatomy characteristics provide important evidences about the transition between C3 and C4 pathways. The C4 photosynthesis pathway allowed to reduce the C3 photorespiratory rate, concentrating CO2 around the Rubisco site and using structures and machinery already presented in C3 plants. In monocots, it is observed a high number of C4 lineages, most of them phylogenetically related to C3 groups. The genus Apochloa (C3), subtribe Arthropogoninae, is related to two C4 genera Coleataenia and Cyphonanthus. The aim of this study was to evaluate four Apochloa species in order to establish anatomical characteristics related to the evolution of C4 pathway in this group. By means of transverse sections fully expanded leaves of A. euprepes, A. lorea, A. molinioides, and A. poliophylla were collected and the characteristics of the mesophyll (M) and bundle sheath (BS) cells were determined. These species showed a rustic Kranz anatomy with enlarged and radial arranged BS cells, which have few organelles organized in a centrifugal position. Although the modifications of BS cells are probably related to the maintenance of plant water status, we also discuss the evolution for the establishment of C4 photosynthesis in the related C4 genera.
RESUMEN Las características de la anatomía de la hoja proporcionan evidencias importantes sobre la transición entre las vías C3 y C4. La fotosíntesis C4 surgió para reducir la tasa de fotorrespiración C3, concentrando el CO2 alrededor del sitio de la Rubisco y utilizando estructuras y maquinaria ya presentes en las plantas C3. En monocotiledóneas, se observa un alto número de linajes C4, la mayoría de ellas filogenéticamente relacionadas con grupos C3. El género C3 Apochloa, que pertenece a la subtribu Arthropogoninae, está relacionado con dos géneros C4 Coleataenia and Cyphonanthus. En este contexto, el objetivo fue evaluar cuatro especies de Apochloa para establecer las características anatómicas relacionadas con la evolución de la via C4 en este grupo. Se colectaron hojas completamente expandidas de A. euprepes, A. lorea, A. molinioides y A. poliophylla y se determinaron las características de las células del mesófilo (M) y del haz de la vaina (HV) a partir de secciones transversales de la hoja. Las especies presentaron una anatomía rústica de Kranz con células HV agrandadas y de distribución radial, con pocas organelas organizadas en posición centrífuga. Aunque las modificaciones de las células HV están probablemente relacionadas con el mantenimiento del estado hídrico de la planta, se puede inferir que facilitan el establecimiento de la fotosíntesis en los géneros C4 relacionados.
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A new species of Axonopus ser. Suffulti from Minas Gerais, Brazil, is described and illustrated. Comparison with morphologically related species, as well as comments on the ecology and the conservation status are provided.
ResumoUma nova espécie de Axonopus ser. Suffulti é descrita e ilustrada para o estado de Minas Gerais, Brasil. São fornecidas comparações com espécies morfologicamente relacionadas, assim como comentários sobre ecologia e estado de conservação.
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A região da Serra Negra constitui um importante remanescente de floresta atlântica situado no sul da Zona da Mata mineira, na Serra da Mantiqueira, composta por um mosaico de campos rupestres (nos afloramentos de quartzito) a arbustais nebulares, florestas estacionais semideciduifólias a perenifólias e florestas nebulares, de ambientes inferomontanos a superomontanos ripícolas a interfluviais. A área de estudo é um fragmento de floresta de grota (floresta perenifólia ripícola), de aproximadamente 0,9 ha, situada no Cânion do Ribeirão do Funil, na Vila do Funil, município de Rio Preto, localizada no sul da Serra Negra. O presente trabalho foi realizado entre os anos de 2004 e 2009 e teve como objetivos o conhecimento da flora vascular não-arbórea, a discussão dos hábitos e habitats das plantas e a descrição da fisionomia do fragmento. Foram registrados 157 táxons de plantas vasculares (sendo 41 pteridófitas e 116 angiospermas), pertencentes a 48 famílias (10 de pteridófitas e 38 de angiospermas). As famílias de maior riqueza específica foram Orchidaceae, dentre as angiospermas, com 27 espécies e Pteridaceae, dentre as pteridófitas, apresentando 11 espécies. O hábito mais representativo foi o herbáceo (124 spp.), destacando-se as espécies epífitas (42 spp.), que perfazem cerca de 25 por cento de todas as espécies registradas na área. Doze espécies estão incluídas na lista de espécies ameaçadas de extinção no estado de Minas Gerais (duas pteridófitas e 10 angiospermas). O elevado número de espécies encontradas em uma área consideravelmente pequena ressalta a importância deste fragmento para a diversidade da Serra Negra e aponta para a necessidade de implantação de um plano de ação para sua conservação.
Serra Negra is an important remnant of Atlantic Forest located in the southern part of the Zona da Mata of Minas Gerais, in Mantiqueira Range, composed by a mosaic of "campos rupestres" (on quartzite outcrops), cloud scrubs, lower-montane to upper montane seasonal semi-deciduous forests or evergreen cloud forests, and riparian to interfluvial forests. Despite floristic importance of this area, there are only two Natural Patrimony Private Reserves: São Lourenço do Funil and Serra Negra. The study area is a ravine forest fragment (evergreen forest), comprising ca. 0.9 ha, localized in the Cânion do Ribeirão do Funil, in Funil Village, municipality of Rio Preto, southern of Serra Negra. The present study was carried out from 2004 to 2009 and its goals were: (1) to survey the non-arboreal vascular flora of the area, (2) discuss plant habits and habitats, and (3) describe the physiognomy of this forest fragment. A total of 157 taxa of vascular plants (41 ferns and 116 angiosperms) were recorded, belonging to 48 families (10 of ferns and 38 of angiosperms). The richest families of ferns and angiosperms were Pteridaceae (11 spp.) and Orchidaceae (27 spp.), respectively. The most representative habit was herbaceous (124 spp.), within which epiphyte species (42 spp.) must be emphasized, representing about 25 percent of all recorded species. Twelve species are cited in the endangered species list of Minas Gerais State (two ferns and 10 angiosperms). The high number of species found in this small area remarks the importance of this fragment for the knowledge of biodiversity of Serra Negra, in particular, and Minas Gerais, in general. In addition, the results reinforce the need of an action plan addressed to the conservation of the region.