Nutrition facts and limits for micronutrients in tree species used in urban forestry.

There is a huge lack of researches that evaluate the nutritional limits in tree species used in urban forestry, especially in terms of micronutrients. This study aimed to establish limits and range of micronutrients levels for the proper development of tree species utilized in urban forestry. The study was conducted in the city of Santa Maria-RS-Brazil. Through forest inventory, 23 forest species present in urban forest were selected, and 05 vegetative branches of each tree were collected, in which the contents of B, Cu, Fe, Mn and Zn were analyzed. Ranges of micronutrients' contents were developed for class limits criteria. Nutritional problems were detected for B, Cu and Zn in G. robusta and S. cumini, indicating a need of fertilization and management of these trees. The levels of Mn were within an adequate range only for the species C. illinoensis and H. chrysotrichus. The contents of B were higher than the level considered adequate for H. chrysotrichusand M. nigra. The rates of Fe showed high levels for E. japonica, H. chrysotrichusand S. babylonica. The estimated nutritional limits enable a greater control in the classification of the results for each tree species utilized in urban forestry.