Parâmetros para avaliação da arborização viária : fitossociologia, morfometria, fitossanidade e índice de risco

Abstract

In urban areas, some conditions such as weather, rainfall, winds, light, soil conditions and air quality are more restrictive to trees. These urban stresses predispose trees to fungal attack by reducing their vigor and opening wounds. Thus, the objective of this research is to evaluate the urban trees on high traffic of vehicular and pedestrian streets in order to identify trees with risk of falling and the presence of fungi associated with urban trees, aiming to establish relations between pathogen, hosts and area of occurrence. The study was carried out in the City of Recife-PE, in three avenues that are relatively parallel to each other, in a stretch of 1,0 km in each one: Marechal Mascarenhas de Moraes Avenue (AVI), Visconde de Jequitinhonha Street (AVII) and Boa Viagem Avenue (AVIII). The morphometric data: Total Height, CAB0.30, Canopy Height, Canopy Diameter and Canopy Projection Area were measured. From these data were calculated the Morphometric Indexes: Canopy Ratio, Slenderness Degree, Outgoing degree, Coverage Index, Shape of Canopy. The Phytosociological Parameters of Frequencie, Dominance and Density in Relative and Absolute values and the Shannon Diversity Index were determined. A Tree Risk Index was generated from an analysis of its parts - canopy, trunk and base of the trunk, and the site to be hit with a possible fall. Collection of leaves with spots were carried out, which were sent to the Laboratory of Phytopathology of the IPA (Agronomic Institute of Pernambuco), where the material was isolated, and the fungi were identified under a binocular microscope. The Terminalia catappa species was among the highest number of individuals in the three areas studied. The species Terminalia catappa, Cocos nucifera and Roystonea oleraceae were the only common species in the three study areas. Most of the individuals presented some problem with the foliage in the three studied areas. Most of the individuals in the three areas had cavities in their trunks and inclined trunks. A high number of individuals had exposed roots in the three study areas. Most of the individuals were infected with at least a phytopathogenic fungi organism. A total of nine genus of phytopathogenic fungi were observed in the tree studied areas. All indivíduos presented some leave spots, which indicates that even in the absent of phytopathogenic fungi, these individuals, possibly, are under nutricional or hidric stress, or presenting syntoms of others phytopatogens as bacterias or nematodes. There is a great need to establish studies on the presence of phytopathogens in species used in urban afforestation, because in each city can be found local problems that have not been recorded in the literature.