RESUMO
Modelos ecológicos de distribuição de espécies (DAEs) em uma comunidade arbórea foram investigados para constatar: (i) se as variáveis ambientais são divididas de maneira estocástica e de modo similar entre as espécies; (ii
ABSTRACT
Ecological Models of Species abundance distribution (SADs) of a tree community were investigated to find: (i) if environmental variables are divided stochastically and similarly between species; (ii) if each species exhausts more than half of the existing ecological niche; (iii) if the tree community has many species with intermediate levels of abundance and a few rare and common species; (iv) and if, in secondary succession, the later colonizing species have greatest needs for a specialized niche, so, they are more rare than the initial colonizers species. The data were obtained in eight sampling units with dimensions of 20m x 50m, distributed in a systematic way, totaling 0.8 ha sample; grouped in five models of SADs (broken-stick, niche-preemption, lognormal, Zipf and Zipf-Mandelbrot)
RESUMO -O inventário das samambaias e licófitas foi realizado no Cerro da Pedra do Lagarto que é um refúgio vegetacional com fitofisionomias distintas, uma florestal e outra campestre, situado no distrito de Santo Antão, ao norte do município de Santa Maria. O objetivo deste estudo foi contribuir para o conhecimento desta flora para a região Central do estado, que ainda é carente de informações sobre o grupo, fornecendo dados ecológicos e biológicos, além de uma chave dicotômica para a identificação das espécies observadas. Foram encontradas 34 espécies de samambaias e duas de licófitas, pertencentes a 28 gêneros de 14 famílias botânicas. Polypodiaceae foi a família com maior riqueza apresentando oito espécies seguida de Pteridaceae com sete. O substrato preferencial evidenciado foi o terrícola e a única espécie de porte arborescente foi Cyathea atrovirens. Os dados inventariados representam 9,5% das espécies de samambaias e licófitas para o estado do Rio Grande do Sul.
Chiococca insularis (Ridley) C.M.Taylor & M.R.V.Barbosa (Rubiaceae) was described by Henry Nicholas Ridley in 1890, based on a collection he made on the island of Fernando de Noronha (Pernambuco, Brazil) in 1887. Since then, this species had not been collected again and has been treated as probably extinct. After 130 years, we discovered two new populations in the southwestern portion of the island, and the conservation status of the species is reassessed. A full description of the species, with previously unseen or unmeasured characters, habitat information and photographs of the plant and environment are provided.
A new species, Rhamnidium riograndense, from southern Brazil, is here described and illustrated. We present information about its distribution, habitat, phenology, conservation status and a key for all the South American species of the genus is provided. The new species is endemic to the central part of the state of Rio Grande do Sul, in the transition between Paraná and Pampean provinces in rocky habitats, mostly mountain slopes, where only four populations are currently known.
Phyllanthus (Phyllanthaceae) is widely distributed within Brazilian phytogeographic domains where 101 species occur, including a number of poorly-known taxa, such as P. allemii, which was until now only known from the type collection. Here we report the rediscovery of P. allemii, which was recently collected during a floristic inventory carried out in the Estação Ecológica Serra Geral do Tocantins, which is located on the border between Bahia and Tocantins states in the Cerrado domain. We provide an updated and detailed morphological description of the species, including plates and field images, as well as a taxonomic key for species of Phyllanthus sect. Phyllanthus subsect. Clausseniani that occur in the Cerrado. We also provide habitat, ecology and distribution data, and, finally, a conservation assessment of this rare species.
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