Aspects of the ecology of hydrophytes in ephemeral wetlands in Malta

Abstract

This study covers the basic aspects of the ecology of hydrophytes of ten pools from three locations in Malta during the period September 1998 to February 2000. A total ofthirty two species were recorded during the field study. Eight species were aquatic/amphibious while the other were terrestrials. The aquatic/amphibious recorded during the study are Lythrum hyssopifolia, Zannichellia palustris, Chara vulgaris, Callitriche truncata, Elatine gussonei, Juncus hybridus, Damasomium bourgaei and Ranunculus saniculaefolius. The most abundant of these were Lythrum hyssopifolia and Zannichellia palustris. The species richness and cumulative coverage of plants in the pools were found to be negatively correlated with the soil depth of the pool. The cumulative coverage was also found to be positively correlated with the maximum water depth of the pool. The study also characterised the seed banks of four other pools. Sediment cores from these pools were analysed and a seed count was taken. Most of the seed cores were surficially biased and were dominated by seeds of Chara vulgaris and Elatine gussonei, that is by the smallest type of seeds. Seeds of Ranunculus saniculaefolius,. Callitriche truncata, and Damasonium bourgaei were also found although in lower abunadances. The abundance of the seeds in the seed bank did not always correlate with the emergent vegetation of the pools. Germination experiments were done to test the effect of seed density on the germination rates of Elatine gussonei, Chara vulgaris, and Callitriche truncata. The results obtained were not conclusive and more experimentation is required to test the hypothesis.