O efeito de borda e suas alterações abióticas determinam a presença de plantas exóticas em um fragmento de manguezal urbano

Abstract

The presence of exotic species has become common in ecosystems, even in adverseenvironmental conditions, such as mangroves. Several factors can influence the occurrence andestablishment of these species, such as local environmental characteristics and the landscape.Landscape characteristics and the edge effect are considered fundamental factors in determiningthe presence of exotic species in urban forest fragments, so that ecosystems located in areas ofintense human influence are generally more invaded. Furthermore, local abiotic characteristicsand aspects of the native community are part of the set of factors that influence the success ofthe establishment of exotic species. However, little research has analyzed these factors in anintegrated way in the mangrove to indicate the best forms of management. Therefore, this studyaims to contribute to elucidating invasiveness in urban mangrove areas, taking into account thepossible interaction between options in the surrounding landscape and edge effect, consideringthe influence of abiotic aspects and the native community. Based on this, it is important to drawattention to conservation efforts that prevent and control invasions in protected mangrove areas,also taking into account the characteristics of the invaded community. For this, the study wascarried out in the Parque Estadual do Cocó Conservation Unit, Fortaleza, Ceará, Brazil. Toanalyze the edge effect and influence of the landscape, we selected transects on the edges of thepark divided into five types of landscapes: urban with a predominance of houses, urban with apredominance of buildings, road, dunes and native vegetation. The transects were formed by 3plots that went from the edge towards the interior of the fragment. In each plot, we analyzedthe structure of the native and exotic community and collected soil samples. In addition, wealso analyze the coverage of each installment. Statistical analyzes were performed usinggeneralized linear models, simple regression models and analysis of variance. Our resultsshowed that there is an interaction between landscape type and edge effect in determining theabundance of exotics, however it was the edge alliance effect and the consequent variation inlocal abiotic characteristics that stood out as determining and limiting the presence of exoticsin the fragment. In view of this, it is necessary that management efforts are directed both tominimize anthropic effects on the edges, and to maintain the normal biotic and abioticconditions of the mangrove, thus minimizing the probability of invasion in this protected area.