Diversidade e arranjo estrutural do componente lenhoso da vegetação de dunas urbanas e não urbanas

Abstract

The dunes are dynamic systems shaped by a high variety of habitats which are responsible for the contention of sandy sediments and maintenance of biological diversity. However, anthropic activities have changed this ecosystem. Given this, this study aims to answer the following question: how is structured the assembly of woody species in urban and non-urban dune? To answer this question, we test the hypotheses: urbanized dunes have less richness, diversity and equability of woody species compared to non-urbanized dunes, and the floristic composition of urban and non-urban dunes will be distinct, so, it will occur in each environment indicator species. The data collection was carried out in the beaches of São Marcos and Caolho (both of them are considered as urban dunes) and on Guia beach and Curupu Island (non - urban dunes). In each area, a phytosociological analysis of the woody component was done by the quadrant method, establishing transects with 10m of distance between them. Each transection quadrants was plotted with distance of 10m between them, totaling 50 points. The Student's t-test was used to verify differences in species richness, a Non-Metric Multidimensional Scale Analysis was used to compare the floristic composition of urban and non-urban dunes, the Hutcheson t-test was applied to verify differences in species diversity in urban areas and non-urban and an indicator species analysis. A total of 87 species were sampled, being 61 species sampled in the urban dunes, 46 spp. and 20 species were common to both environments. The results show that the diversity was greater in the non - urban dunes than in the urban dunes, in relation to the equability the vegetation of the urban dunes is less heterogeneous than in the non - urban dunes, since the average species richness was higher in the non - urban dunes. It is possible to infer that the constant removal of vegetation for the advancement of urbanization and tourism, promote the formation of open areas associated with environmental characteristics such as high luminosity and low soil moisture, are favorable conditions for the establishment of invasive plants with great colonizing potential and recruiter. The establishment of these species may lead to a reduction in the coverage of natural species, destabilizing the community and promoting the establishment of invasive or generalist species, which contributes to increase the specific richness. However, destabilizing the diversity and equability of the plant community. In the analysis of indicator species from the indication value, a list was obtained with 11 species considered typical of the non-urban dunes and six of the urban dunes, thus it is possible to observe that the indicator species make up the group of species most representative of each environment. Considering the data presented in this study, it is emphasized the urgency in the use of measures of restoration and conservation of the urban dunes as a way to guarantee the resilience process and the continuity of the ecological processes of these areas.