Effects of urban ecosystem under the diversity and structure of two forest ecotones in Maranhão state

Forest ecotones show a great floristic diversity, but anthropogenic disturbances may imply in their vegetation structure reduce. This study aimed to evaluate the understory diversity of an urban and nonurban forests in Maranhão state. We tested the following hypotheses: 1) the understory of the non-urban forest has greater richness and diversity; 2) the spatial distribution of diversity in the non-urban understory has weak spatial dependence. The study was carried out in the São Luís (urban area) and São José de Ribamar (nonurban area) cities. Thirty plots (25m 2 ) were allocated in each area and the all tree individuals up to 2 m in height were measured. Density, frequency, importance value, cover value, Shannon index (H’), and Pielou index (J’) were calculated. The Mann–Whitney test, non-metric multidimensional scaling, and Hutcheson t-test were used to analyze if there were any stastical difference between the richness, density, and diversity of both areas. We used the ordinary kriging in order to visualize the variation in richness and diversity of the vegetation. There was a difference in the floristic composition and density of each species in the two areas; the richness and diversity were significantly greater in the nonurban area. Weak spatial dependence was found in the urban area, suggesting de-characterization the fragment. The presence of urbanization in the ecotonal forest fragment has reduced the richness, diversity and spatial dependence of the understory. The diversity is high even with the changes caused by urbanization, due to the ecotonal nature of the fragments sampled.