Growth modeling of the crown and trunk of Handroanthus heptaphyllus and Platanus x acerifolia trees in the southern Brazilian urban forest

Crown diameter of H. heptaphyllus and P. acerifolia stabilizes around 40 years, reaching 15 m and 13 m respectively, and models guide spacing planning and ecosystem service estimates in urban forests. The growth pattern of urban trees influences both planning of urban forest composition and estimating ecosystem services, with crown diameter (CD) being the most important variable. However, there is a lack of models that relate diameter at breast height (DBH) growth to crown diameter, especially under the environmental conditions of Brazilian cities. In this study, we fitted models to estimate the temporal growth of DBH and CD for two species widely planted in southern Brazil: H. heptaphyllus and P. acerifolia. Models relating CD and DBH, DBH growth models, and CD growth curves over time were developed. The best models for estimating CD based on DBH showed the following goodness-of-fit statistics: adjusted R2 = 0.56, Syx(%) = 13.42, and RMSE = 1.67 for H. heptaphyllus; and adjusted R2 = 0.82, Syx(%) = 8.42, and RMSE = 0.89 for P. acerifolia. The Chapman-Richards model showed adjusted R2 = 0.85 and Syx(%) = 37.96 for H. heptaphyllus, and adjusted R2 = 0.87 and Syx(%) = 36.72 for P. acerifolia. The CD growth curves reach stabilization at around 40 years of age, with mean crown diameters of 15 m and 13 m for H. heptaphyllus and P. acerifolia, respectively. The information generated is relevant for urban forest planning and management, supporting conflict prevention with urban infrastructure and maximization of the ecosystem services provided by urban trees.