Analysis of variance was used to test for effects of multiple wood ash application on soil chemical properties and foliar concentration of macroelements and microele­ments, with the PROC GLM procedure of SAS (SAS Institute 2004).

Normal diameter and total height were measured annually in all trees within the plots at the end of the growing season for a period of 3 years. The breast diameter was measured in two directions with a caliper, to an accuracy of less than 1 mm. Tree height was measurement with a Vertex III hypsometer. A volume equation based on the allometric model of Schumacher and Hall was used to calculate the tree volumes. The parameters of this model were estimated by Castedo (2004) by use of the following expression:

v = 0.000048 x d20062 x ht0’86691,

where v is the bark volume (m3) of individual trees; d is the breast diameter in centimeters, and ht is the total height in meters. The total height and breast diameters were compared by repeated measurement analysis with the PROC GLM procedure of SAS (SAS Institute 2004) after prior confirmation of the assumptions of equal (Levene test), normal (Kolmogorov-Smimov test), and inde­pendent variance. The mathematical model used was as follows:

yij = m + pxit + Ti + Dj + Ti x Dj + eij,

where yij is the random variable representing the value in the jth observation of the ith treatment, m is a constant representing the mean response of the variable; pxit models the linear relationship between the response and the covariate (initial height or diameter measured before the application of ashes), Ti and Dj are the effects of treatment i (control, WA, and WAP) and the time j (0,1,2,.. .4 measurements), respectively, Ti x Dj is the interaction effect of treatment i by time j, and eij is the experimental error.