Possible causes for the decline of the water soldier (Stratiotes aloides L) in the Netherlands

摘要: Forty-five locations in peaty lowland areas, where Stratiotes aloides L. was studied August/September 1980, were again February and 1992. Water sediment pore water samples collected vegetation surveys made. Furthermore, nutrient analyses made of differently aged tissues plants had disappeared from 24 the 45 locations. Analyses revealed that this decline could most probably be attributed to changes hydrological conditions. As a result modern agricultural practice ground levels are generally lowered, especially summer. To prevent peat drying out, sulphate enriched alkaline is let in. Sulphate reduction concomitant iron sulphide precipitation, as well decreased inputs due influence, appear increased water. plant growth appears become limited while roots die toxification. phosphate release sediments enhanced Sixteen locations, since dominated by non-rooting species covered almost entire surface. In 5 still present, co-dominant appeared overgrow stands. Finally ammonium strongly disappeared. We, therefore, suggest multiple environmental stress hypothesis including light competition species, limitation, toxicity possible causes for Netherlands, at least last decade.