Aquatic vegetation types vary with the water type and quality. Generally speaking, they will do well in young parks where there are many opportunities, with new water conditions and usually a good water quality. During the first few years its development may be spectacular but, as the park ages, restrictions on water plants will often arise.
Unfavourable influences
Many people are familiar with the rich young vegetation of Ceratophyllum, Elodea, Potamogeton, Nymphoides peltata, Butomus umbellatus, Scirpus and Typha. In the long run, they are strongly reduced by increasing shade on the water, degradation of banks through erosion, increasing quantities of mud,, strong development of thread algae caused by eutrophic water, and a generally decreasing water quality. As the park grows older, one is confronted with these developments. Nymphoides peltata will no longer grow in muddy water bottoms. Embankments with Caltha palustris and Senecio paludosus that are in decline, as a result of increasing shade, may be replaced with more shade-tolerant species, such as Filipendula ulmaria, Angelica sylvestris and Lysimachia vulgaris.
By reconstructing shallow banks using underwater reinforcements, one may create new opportunities. Generally speaking, the bottom of water bodies are held together by the roots of emergent species such as Typha, Butomus and Phragmites. Where they are not present, the bottom of water bodies erode, with shallow spots becoming deeper again. One can raise them with mud produced by erosion and decayed waterplants from elsewhere in the park. The phenomena of now rich and then poor years of Lemna, Spirodella and Azolla, the increase or decrease of species such as Ranunculus, Nymphaea and Nuphar are hard to explain. They may be connected to climatic factors, which seem to influence water habitats more strongly than others.
