Impact of tree species on forest soil acidification

Seven forest tree species were tested for their impact on the rate of soil acidification, using both analytical and experimental methods. Soils were investigated by usual analytical methods, and two experiments were carried out on 20 acidic sites where several tree species had been planted. Test-minerals and cation-exchange resins were inserted into soil layers (litter; A and B horizons) and then maintained over various periods. The results of these experiments were interpreted with reference to the theory of acidolysis and acidocomplexolysis developed by Robert et al. [Robert, M., Razzaghe, M., Vicente, M.A., Veneau, G., 1979. R (o) over cap le du facteur biochimique dans l'alteration des mineraux silicates. Sci. Sol. 2 (3), 153-174.]. The main conclusions were as follows: (i) The nature of the parent material strongly influenced the weathering of the test-mineral; (ii) Acidification and weathering took place particularly during the dormant period; (iii) Norway spruce (Picea abies Karsten) enhanced the acidification of soils and weathering of test-minerals in comparison with the other tree species tested under the same conditions; (iv) In this study, the effects of tree species were minor in comparison to the other factors. (C) 1998 Elsevier Science B.V.