Distribuição espacial de Mesadenella cuspidata (Lindl.) Garay (Orchidaceae) em uma floresta ribeirinha em Santa Maria, RS, Brasil Spatial distribution of Mesadenella cuspidata (Lindl.) Garay (Orchidaceae) in a riparian forest, Santa Maria, RS, Brazil

Mesadenella cuspidata é uma orquídea terrícola encontrada no interior de florestas no Sul do Brasil. Apesar de seu valor ecológico e ornamental, pouco se conhece sobre a biologia desta espécie. Os objetivos deste trabalho foram identificar o padrão de distribuição espacial de M. cuspidata e verificar se há correlação entre o número de indivíduos jovens e adultos em uma floresta ribeirinha. Para o levantamento, foram amostradas 60 parcelas de 16m² cada. Durante agosto e setembro/2001 foram inventariados os indivíduos jovens e adultos das parcelas. Para identificar-se o padrão de distribuição espacial, utilizaram-se o índice de Morisita (MI) e a razão de variância/média (R). Foram encontrados 463 indivíduos jovens e 178 adultos. Indivíduos jovens e adultos apresentaram distribuição espacial agrupada, sendo que os adultos (IM = 2,17; R = 4,52) estão mais agrupados que os jovens (IM = 1,82; R = 7,82). O coeficiente de correlação linear encontrado r = 0,61, demonstrou que a densidade de indivíduos adultos está altamente relacionada à densidade de indivíduos jovens.<br>Mesadenella cuspidata (Lindl.) Garay is a terrestrial orchid found inside Southern Brazilian forests. In spite of its ecological and ornamental value, little information is aviable on its biology. The aim of this work was the identification of the spatial distribution patterns of M. cuspidata in a riparian forest. We have sampled 60 quadrats of 16m² each. All the young and adult individuals of the quadrats were included. To identify the pattern of spatial distribution, the Morisita Index (MI) and the variance/mean Reason (R) were used. The linear correlation coefficient was used to verify if there is correlation between populations of the juvenils and adults. From 641 individuals sampled, 463 were juvenils and 178 were adults. Juvenils and adult individuals presented gregarious spatial distribution, but the adults (MI = 2,17; R = 4,52) were more gregarious than the juvenils (IM = 1,82; R = 7,82). The high relation between the densities of adults and juvenils had been demonstrated by the value of the linear correlation coefficient found, r = 0,61

Neotropical flowering epiphyte diversity: local composition and geographic affinities

Worldwide, the highest diversity of vascular epiphytic plants resides in the Neotropics. The general pattern of taxonomic composition of the neotropical epiphytic flora has been described, but information regarding the magnitude and geographic distribution of species richness is lacking. In this paper, we carried out a regional scale analysis in order to provide an overview of the richness, composition and geographic affinities among several neotropical epiphyte floras. Our database comprised 7,524 flowering epiphyte species (48 % of the estimated total of neotropical epiphytes) from eight representative localities with politically-defined boundaries. The epiphyte quotient (e.g., percentage of epiphyte species in the total flora) per locality ranged from 5.2–27.7 % (mean: 17.5 %) of the flowering plants. Ecuador represented the most species diverse locality (4,247 spp.), followed by Costa Rica (2,611 spp.). At the family level, the epiphyte composition among localities was roughly homogeneous and dominated by emblematic epiphytic groups: Orchidaceae, Bromeliaceae, and Araceae. However, the generic composition of the epiphytic floras was more heterogeneous. Ecuador and Cuba showed the highest epiphyte endemism (37 and 26 %, respectively), and in some cases vascular epiphytes represented 30 % or more of the total endemic flowering plants at a particular locality. From the available information, four main regional epiphyte floras were identified: the northwestern Andean region, the northern and southern Mesoamerican regions; Cuba as a representative of the Caribbean region remained as a separated group, though weakly related to the Mesoamerican groups. This study identified important geographic localities as targets for the conservation of neotropical epiphyte diversity.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí