Felipe Cito Nettesheim

Influence of environmental variation on Atlantic Forest tree-shrub-layer phytogeography in southeast Brazil

O presente trabalho analisou dados de 32 remanescentes florestais nos estados do Rio de Janeiro e Sao Paulo, atraves de analises multivariadas para responder a pergunta: Existem padroes floristicos do estrato arboreo-arbustivo da Floresta Atlântica relacionados a Serra do Mar e alargamento das planicies costeiras nos estados do Rio de Janeiro e Sao Paulo? Foram utilizadas tres analises multivariadas para investigar as relacoes entre a flora arboreo-arbustiva e a variacao ambiental das 32 areas. As analises demonstraram influencia de alteracoes geo-climaticas sobre a diferenciacao floristica das especies arboreas e arbustivas da Mata Atlântica. Este fato permitiu gerar grupos com as areas analisadas baseados em caracteristicas bioticas e abioticas, sustentando a existencia de padroes floristicos nos estados do Rio de Janeiro e Sao Paulo. Os grupos formados refletem a substituicao das especies arboreo-arbustivas entre as areas analisadas como consequencia de variacoes da precipitacao, altitude e temperatura media anual a medida que modifica o posicionamento da Serra do Mar e cresce a planicie costeira. Para cada grupo foram designadas especies preferenciais que devem ser consideradas em programas de restauracao e conservacao das regioes fitoecologicas por eles representadas.

Estrutura e florística do estrato arbóreo no cerrado sensu stricto de Buritis, Minas Gerais, Brasil

( Estrutura e floristica do estrato arboreo no cerrado sensu stricto de Buritis, Minas Gerais) . A crescente perda de cobertura do cerrado sensu stricto vem demandando mais estudos sobre sua ecologia para auxiliar em sua conservacao. Este estudo caracteriza a composicao floristica e estrutural do estrato arboreo de um cerrado sensu stricto e testa sua similaridade a outros locais com fisionomia similar. Atraves de parcelas, foi amostrada uma area de 1,45 ha, registrando-se individuos com DAS ≥ 10 cm. Foram calculados os parâmetros estruturais, indice de Shannon (H’), equitabilidade de Pielou (J’) e analisada a distribuicao de especies em classes de diâmetro, enquanto a distribuicao de individuos, em classes de altura e diâmetro. O estudo foi comparado a nove cerrados sensu stricto atraves da analise de similaridade. Registrou-se 1155 individuos, 90 especies, 73 generos e 37 familias. H’ foi igual a 3,75 e J’ igual a 0,83. Qualea grandiflora, Magonia pubescens, Curatella americana e Qualea parviflora apresentaram os maiores valores de importância. A densidade foi 796 individuos/ha e a area basal somou 11,87m 2 /ha. O estudo demonstra maior semelhanca entre o cerrado sensu stricto de Buritis e o encontrado sobre solos rochosos no norte de Goias e sul de Tocantins, alem de detectar padroes floristicos que apontam a relacao da flora arborea entre diferentes areas no Brasil central.

Different slopes of a mountain can determine the structure of ferns and lycophytes communities in a tropical forest of Brazil

A community of Ferns and Lycophytes was investigated by comparing the occurrence of species on different slopes of a paleoisland in Southeastern Brazil. Our goal was to evaluate the hypothesis that slopes with different geographic orientations determine a differentiation of Atlantic Forest ferns and lycophytes community. We recorded these plants at slopes turned towards the continent and at slopes turned towards the open sea. Analysis consisted of a preliminary assessment on fern beta diversity, a Non Metric Multidimensional Scaling (NMDS) and a Student t-test to confirm if sites sampling units ordination was different at each axis. We further used the Pearson coefficient to relate fern species to the differentiation pattern and again Students t-test to determine if richness, plant cover and abundance varied between the two sites. There was a relatively low number of shared species between the two sites and ferns and lycophytes community variation was confirmed. Some species were detected as indicators of the community variation but we were unable to detect richness, plant cover or abundance differences. Despite the evidence of this variation between the slopes, further works are needed to evaluate which processes are contributing to determine this pattern.

FATORES DO MEIO FÍSICO ASSOCIADOS AO ESTABELECIMENTO DE ESPÉCIES RÚSTICAS EM ECOSSISTEMAS PERTURBADOS NA MATA ATLÂNTICA, PIRAÍ, RJ - BRASIL

Disturbed ecosystems do not present original floristic composition. Their soils are depleted, shallow, stony, with low infiltration and present erosion with different levels of geodynamics. The study region has areas of pasture with sparse herbaceous vegetation which is weakened in every rain and fire, covering less ground. The individuals that colonized and settled in these environments were considered rustic species. This study raised and identified by census, the rustic species and their structure in the most degraded part (lower third) of the watershed of Cacaria’s river at the base of the Serra do Mar, Pirai, Rio de Janeiro state, and evaluated the influence of ecological exposure, slope, elevation, topography and rock outcrops in the establishment and growth of these species. For the vegetation survey it was conducted census in an area of 22 hectares, where it was measured, geo-referenced and identified all spontaneous tree species that were isolated in a

Environment is more relevant than spatial structure as a driver of regional variation in tropical tree community richness and composition

ABSTRACT Background: Understanding how factors related to environment and geographical distance explain community variation allows insights about how ecological niche and neutral processes control tropical community assembly. Aims: Quantify how variation in regional tree community richness and composition in a humid tropical forest across a mountain chain are related to niche and putative neutral processes. Methods: We used a variation partitioning routine based on Redundancy Analysis to model tropical tree community richness and composition within three distinct elevation belts, as a function of environment and spatial structure, using data from 32 studies in the Serra do Mar Range, south-eastern Brazil. Results: Environmental effects were greater than spatial structure effects to explain community variation in the three elevation belts. There was a trend of decreasing spatial structure effects while environmental effects remained constant from lower to higher elevations. Patterns were congruent for species richness and composition. Conclusions: We suggest that on tropical mountains, niche-related processes are equally relevant for tropical forest community assembly at all elevations, while neutral processes become weaker towards higher elevations. Determining if this trend is a consequence of the greater heterogeneity of environmental conditions associated with higher elevations in tropical mountainous terrain remains an important area of research.