An Experimental Approach to Part of the Calcicole Problem

Abstract

The sedges Carex lepidocarpa and C. demissa were grown in field and water culture experiments to try to account for the restriction of C. lepidocarpa to calcareous habitats (calcicole behavior). The seedling stage is the most sensitive stage. More than 30 ppm Ca++ gives better growth and survival of C. lepidocarpa than of C. demissa. In addition there is some factor in the base-poor pH 4.2 soil (identified as Al+++ at more than 1.0 ppm), which is removed by raising the pH and which is more toxic to C. lepidocarpa than C. demissa. Growth of both species is the same in natural soil solutions and in solutions made up to resemble them chemically in amounts of 14 ions. Water analyses from natural habitats are not inconsistent with culture experiments. The difference between the species in sensitivity to Al+++ is a common feature of samples from a wide geographic range. The most obvious effect of Al+++ is to prevent root growth. Chelated Al does not have the effect of Al+++ ion and the inhibition of growth is not owing to external precipitation of ortho-phosphate .