FACTORS TOXIC TO BEECH (FAGUS-SYLVATICA L) SEEDLINGS IN ACID SOILS

The effects of highly and moderately acid soils on total biomass, biomass partitioning, fine root characteristics and nutritional status of beech seedlings (Fagus sylvatica L.) were studied in a growth chamber experiment. In Haplic Arenosols seedlings grew slowly but equally well without damage symptoms in a highly acid and a moderately acid soil horizon. The moderately acid A(h) + B(w)-horizon of a Eutric Cambisol was favourable to seedling growth. The fine root development was reduced in the highly acid A + B(w)-horizon of a Dystric Cambisol and in the A(h) + E-horizon of a Haplic Podzol, the latter of which also caused increased mortality. Seedling growth in the B2-horizon of the Haplic Podzol was vigorous, in spite of a higher level of extractable Al and lower base saturation as compared with the A(h) + E-horizon. These results are interpreted in relation to soil acidity, soil Al and nutritional status of the seedlings. We conclude that neither Al-toxicity nor nutrient deficiency cause the damage symptoms observed in the A(h) + E-horizon of a Haplic Podzol and the fine root reduction in the A + B(w)-horizon of a Dystric Cambisol. The damage symptoms of the PZh(A) treatment seems to be more the result of H-toxicity or H-related factors other than nutrient shortage or Al-toxicity. Other pH-related toxic factors are discussed.