CARACTERIZAÇÃO DO ESPAÇO DE CRESCIMENTO E MODELAGEM DO DIÂMETRO DE ANCORAMENTO DE ÁRVORES EM CALÇADAS

Abstract

The intense and disordered expansion of cities has been causing increasing problems related to the lack of physical space to trees development. Thus, the minimal width of the flowerbed must be an important requirement to avoid that the trunk flare diameter does not damage sidewalks and other urban infrastructures. This research intends to analyze the space occupied by trees in relation to the structure of sidewalks and pedestrians’ accessibility, moreover, it intends to model the trunk flare diameter of tree species planted in sidewalks of Frederico Westphalen town, in the state of Rio Grande do Sul, Brazil. In a way to perform the research, data from 400 trees of 10 species commonly used in the afforestation of sidewalks. For each species, data of quantitative and qualitative aspects of trees and urban structures were analyzed. The width of the path was used as a variable to examine the accessibility of pedestrians, dividing the data between two categories: type 0 (< 120 cm) and type 1 (≥ 120 cm). Data of the flowerbed capacity were divided into three categories: type 0 (< 50 cm); type 1 (50 cm ≤ 100 cm) and type 2 (> 100 cm) to evaluate if the individuals presented minimal flowerbed capacity or not. In order to evaluate the rate between anchorage and width of the flowerbed, the difference was divided into three categories: type 1 (< 50 cm), type 2 (50 cm ≤ 80 cm) and type 3 (> 80 cm). By using these classifications, the Canonical Correspondence Analysis (MCA) was done to extract information on the tree occupation space. Also, it was verified if the amount of soil was appropriate to each tree by using the rate “volume of soil multiplied by tree top”, simulating two situations: situation 1: width of the sidewalk multiplied by 4 (minimum space between trees on sidewalks) and situation 2: flowerbed width multiplied by 1 (minimum flowerbed width). The CCA rate for the accessibility of sidewalks in Frederico Westphalen town, the majority, 90,25%, of individuals are planted in places where the sidewalks are accessible and the rest in places without accessibility. Regarding the capacity of the flowerbed, 60,25% of the individuals present conditions of sidewalks with appropriate capacity, and 39,75% of them are located in spots where it is necessary the increase of flowerbeds capacity in a way to improve the development of trees. In relation to the amount of soil, in “situation 1”, 72,25% of the specimens do not have the appropriate amount, while on “situation 2” this rate is 100%. The covariance analysis (ANCOVA) allowed to understand the need for a model to each species when trunk flare diameter is out of the range from the variation data observed in this study, otherwise, the general model can be used. The selected models were constructed by using lnDBH and ! " variables and presented R2 = 0,5354 to all the species and to each species the R2 were over 0,3549. The estimate standard error was inferior to 27,05 cm and variation coefficients inferior 61%. It is concluded that most of sidewalks in the town are accessible and most individuals have the capacity of the appropriate flowerbed. Regarding the amount of soil available, a large part needs to increase this amount and it is suggested to use the models generated in this study to assist in the planning and management of urban forest, as well as the accessibility and infrastructure of the municipality.