development of dual nutrient diagnosis ratios for basswood, american beech, and white ash.

foliar analysis of natural deciduous tree species of basswood (tilia americana l.) (ba), american beech (acer grandifolia enrh) (be), and white ash (fraxinus americana l.) (wa) was carried out in 1994 in southern quebec. the diagnosis and recommendation integrated system (dris) was developed from the traditional method to find the preliminary norm and indices of n, p, k, ca, and mg for the above species. the growth decade 1983-1994 in a high yielding sub-population was used to develop dris norms for the identification of dris functions and indices in relatively depleted levels of those elements in the declined growth of three species. foliar nutrient deficiencies were found with k (-3.72) and n (-2.96) for basswood, ca (-10.43) and mg (-4.93) for beech, and n (-6.16), ca (-2.56) and k (-2.05) for white ash. the dris analysis indicated that basswood and white ash were relatively depleted of k and n, while beech had a deficiency of ca and mg, and white ash had a limitation of n. these results suggest the usefulness of dris for foliar tissue analysis as an indicator of nutritional status and elemental stresses in natural forests. the dris indices were also discussed from the traditional approach.