ABSTRACT
This study had as objective to evaluate nutrients content and allocation pattern in different biomass components of Platanus x acerifolia, in a 5.5 year stand, located in Dom Feliciano, Rio Grande do Sul state. Twenty-four trees were sampled, based on diametric amplitude, with biomass determination in the following components: leaves, fruits, stem bark, wood and roots. To study the variation of nutrients concentration, wood and bark samples were collected in different positions along the stem. Nutrients stock estimation, in each component, was based on biomass average values and nutrients content, by the number of trees per diametric classes per hectare. Nutrients content variation along the stem, in bark and in wood was studied based on regression equations adjustment, correlating nutrients concentration and the point of collection. Considering all biomass components, the following sequence according to nutrients concentration was: N > Ca > K > Mg > P > S > Fe > Mn > B > Zn > Cu. The highest contents, for most nutrients, were observed in leaves and the lowest, for all nutrients, were observed in the wood. Total nutrients stock in Platanus x acerifolia biomass was 574.72 kg ha-1, according to the following allocation order, among the components: wood ~ branches > roots ~ leaves > bark > fruits. Regarding to nutrients, the accumulation sequence was as follows: N > K > Ca > Mg > S > P > Fe > Mn > B > Zn > Cu, where N, K and Ca represent 82.9% from the total. It was verified a great variance in nutrient concentration along the stem, bark and wood, with distinction of basic patterns: growing, decreasing and invariable, from the base of the tree towards to the top.
Keywords:
nutrients cycling; nutrients stock; biomass sampling