Abstract
ABSTRACT Tree crown form can be used as a variable to the comprehension of factors that influence tree growth, mainly maintenance practices and interactions with urban structures, but also the potential risks that can exist. In this research, we aimed to evaluate crown projection unbalance of trees planted on sidewalks of three Brazilian cities, in order to determine the existence and the sort of asymmetry and crown angle formed in relation to the central axis of the trunk. We measured the length of four crown projection radii and compared them by means of Kruskal-Wallis Test. Each one of the crowns was framed in one of the four asymmetry classes to verify the uniformity of projection in relation to the central axis of the trunk. We also determined the distance between central axis of the trunk and crown centroid, with respective angle formed, in order to characterize the unbalance of crown projection. There was a significant difference among crown projection radii, with greater values to radius faced to street and the smallest ones faced to buildings. In the three cities evaluated there were a predominance of trees framed on class 3 of asymmetry, which represents the model with the greatest deformations on crown of trees. We observed the lowest mean angle of crown centroid projection with distinctions among species sampled in Bonito.
Highlights
Changes caused to natural ecosystems by the urban process and land use has been modifying natural landscapes and creating a big greyish and impervious matrix intersected by patches and plant corridors formed by trees along sidewalks, squares and urban parks
Canopy cover and size of trees are characteristics directly associated with freshness effect promoted by trees in urban areas (MULLANEY et al, 2015), but pruning activities can change tree crown projection and the effects related to this part of trees
The goals of this research were to dimension the radius crown projection of trees comparing them statistically, to describe and analyze crown asymmetry classes and the angle of crown centroid in relation to trunk central axis of forest species planted on sidewalks of three Brazilian cities
Summary
Changes caused to natural ecosystems by the urban process and land use has been modifying natural landscapes and creating a big greyish and impervious matrix intersected by patches and plant corridors formed by trees along sidewalks, squares and urban parks. In this scenario, Baur et al (2016) stated that all over the world the fast population growth generated challenges to urban management in order to provide human well-being and environmental quality. Tallis et al (2011) emphasize the mitigating effect of trees and urban green areas against atmospheric pollution and particulate matter caused by car traffic. Canopy cover and size of trees are characteristics directly associated with freshness effect promoted by trees in urban areas (MULLANEY et al, 2015), but pruning activities can change tree crown projection and the effects related to this part of trees
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