This study develops a data-transformation method useful in correlating species importance with habitat factors. The relative basal area of six major tree species is examined in relation to data on eight environmental factors. A parabola transformation makes the dome-shaped importance response into a more linear relationship. The transformed data then are examined by a multiple regression of the response of each species to eight factors. The regression yields a numerical estimate of the relative influence of each factor in increasing or decreasing the importance of each species. The regression also yields an estimate of the extent to which variation in species importance is accounted for by the environmental influences present in the study area. Regression with parabola transformation accounts for as much as 80% of the variation in individual species importance. Simpler linear multiple regression accounts for no more than 65% of the variation.