RELATIVE IMPORTANCE OF EXCHANGEABLE AND SOIL SOLUTION CATION CONCENTRATIONS TO THE DISTRIBUTION OF VASCULAR PLANTS

The distribution of the 11 most frequent vascular plant species in a beech forest with highly variable top-soil chemistry in southern Sweden was compared to the concentrations of cations in the soil solution (obtained by centrifugation) and the exchangeable soil pool (obtained by extraction with 0.1 M BaCl2). Cations analyzed were H, K, Ca, Mg, Mn and Al (in soil solution, both total and easily-reacting Al). The plant species considered were Anemone nemorosa, Deschampsia flexuosa, Gagea spathacea, Galium odoratum, Lamium galeobdolon, Luzula pilosa, Melica uniflora, Milium effusum, Oxalis acetosella, Stellaria holostea and Stellaria nemorum. The exchangeable and soil solution fractions of most cations accounted to the same extent for the distribution of plants. Close relationships to plant distributions were found at the upper and lower pH intervals studied. The distribution of species at intermediate pH could only marginally be accounted for by soil cation concentrations.