Population structure of Microgramma vacciniifolia (Langsd. & Fisch.) Copel in an Open Ombrophylous Forest fragment in Northeast Brazil

Abstract

The species Microgramma vacciniifolia (Polypodiaceae) is found as corticicolous and/or growing-rock plant, with a wide geographic distribution, occurring throughout the Americas. The study was conducted in an Open Ombrophylous Forest fragment, located in the municipality of Areia, Paraiba State, aiming to collect data regarding the populational structure of M. vacciniifolia. To make the survey, 10 transects with six plots each with dimensions of 10 x 10 m were established. For the quantitative study, two types of analysis were focused: (I) the horizontal distribution, where were calculated the absolute density (AD), absolute frequency (AF) and Morisita Index of Dispersion (Id); (II) and vertical distribution, where were calculated the absolute frequency of individual phorophytes (AFi), the absolute frequency of specific phorophytes (AFj) and absolute frequency strata (AFe). The number of individuals was correlated with the species, height, and CBH (circumference at 1.3 m above the ground) of phorophytes, edge distance and luminosity. An analysis was made to visualize the spatial distribution of the number of individuals in the studied fragment. The interpolation of the data was made using Natural Neighbor method (NaN). The results showed that the species is well adapted to the environmental conditions of the fragment, present in its different regions. The species was found in phorophytes with different ages (CAP and height), and in all pre-established strata; The results suggest that the taxon has a wide ecological valence for different climatic factors and is able to withstand harsh environments with very different states of conservation.