Ajuste de modelos matemáticos lineares e não lineares para estimativa de biomassa e nutrientes de Anadenanthera colubrina var. cebil no semiárido pernambucano

Abstract

The objective of this study was to test different mathematical models to estimate the biomass and nutrient contents from the aerial parts based on the dendrometric variables of Anadenanthera colubrina var. cebil (Griseb.) Altschu from semiarid Pernambuco and select the best equation based on statistical criteria of adjustment index, standard error of estimation and graphic distribution of residues. 20 individuals were selected for biomass and 10 for nutrients. Different mathematical models were tested in order to estimate quantities of biomass and nutrients, using as the dependent variable biomass weight in kg of nutrients (N, P, K, Ca, S, Mg); and as independent variables the diameter at breast height (1.3 m); the overall height (HT) and commercial (HC) trees. For biomass and overall nutrient the equations showed good fits; however per compartment of the trees it was not possible to get good equations for some nutrients (P, K, Mg). The accuracy of the adjustments was good for the other nutrients (N, Ca, S) and green biomass.