EFFECTS OF LIMING ON SHALLOW ACIDIFIED MOORLAND POOLS - A CULTURE ANDA SEED BANK EXPERIMENT

To study the effects of liming on water chemistry and the development of aquatic macrophytes, culture experiments with Littorella uniflora ( L.) Aschers. and Juncus bulbosus L. were carried out. The addition of powdered limestone to acidified moorland pools led to increased phosph ate levels in the water layer and increased carbon dioxide levels in t he sediment pore water and the water column; this resulted in an exces sive growth of Juncus bulbosus. Similar observations were made in seed bank experiments, conducted in a greenhouse. After 2 years the abunda nce of J. bulbosus was very high. Littorella uniflora and Lobelia dort manna L. germinated spontaneously and developed in mini-ecosystems wit h sediments from the Padvindersven and the Peetersven, respectively, t wo moorland pools from which these species had disappeared a few decad es ago, Spontaneous germination and development of endangered soft wat er macrophytes only occurred on sediments after removal of the organic sapropelium layer. Therefore, this study showed that in order to rest ore the original water chemistry of acidified moorland pools, removal of the organic sapropelium layer is necessary, as well for improving v egetation development.