Efeito do nível freático e da população de Ligustrum lucidum W.T.Aiton na dinâmica em fragmento urbano de Floresta Ombrófila Mista Aluvial

Abstract

The alluvial areas of the forests have had an important ecological function in the maintenance of water resources and in the conservation of species, however, they are threatened by human activities. This study aimed to characterize the floristic and structural descriptors of an urban fragment of Mixed Alluvial Ombrophilous Forest, in the city of Guarapuava-PR. Soil water conditions were estimated, which formed groups according to the water table position, evaluating the horizontal structure and comparing the indices of diversity, dominance, equability and similarity between the groups. Also analyze the horizontal and vertical structures of the forest, as well as the dynamics from 2011 to 2020 and observe the changes associated with L. lucidum in the local population. The fragment is part of the hydrographic basin of the Rio Cascavel, in the urban area of Guarapuava-PR, corresponding to an area of 11.5 ha, with 72 permanent plots of 100 m² each. In 2020 the trees had their height estimated and the DBH remedied, taking into account the mortality and entry of new individuals. In 2011, the density was 2,075.0 ind ha-1, in 2020 the density increased to 2,462.5 ind ha-1, divided into 4 groups, where the group with plots in soil of greater hydromorphy showed lower values of diversity and high levels of dominance and similarity with the forest. Sebastiania commersoniana, Matayba elaeagnoides and L. lucidum are the species with the highest phytosociological descriptors. In relation to L. lucidum, it was noticed that the species has a high invasive potential, with competitive capacity, presenting higher height and diameter averages than the natural species of the forest, with an increase in basal area for both the species and the forest in general. Furthermore, during the evaluation period L. lucidum was the dominant species in the middle stratum and the third that most increased in diameter during the studied period, obtaining low mortality rates, high entry rates and rapid growth, indicating adaptability to the studied fragment. The results of this work indicate that more research is needed to quantify the invasive potential of the species and that management actions are necessary for a better development of the natural forest.