Management in freshwater ponds and shallow lakes in the Netherlands: A review of the effects on emergent vegetation diversity and terrestrialisation

From recent literature it is clear that most management in ponds and shallow lakes is focused on the water body itself. Mostly the aim is to reduce nutrient availability, so to restore the clear water state including the aquatic vegetation. Given the fact that the water and the banks interact closely with one another, it is necessary to view them as an integrated system. Several measures beneficial to the aquatic system are also beneficial for the creation of diverse emergent vegetation, making them perhaps more effective than previously thought. In this thesis, nine different management options (grazing, mowing, cleaning, burning, dredging, biological management, water level manipulation, chemical treatment and bank restoration) were examined for their effects on the expansion of emergent vegetation into open water and the diversity of the vegetation. Of the environmental factors, expansion into open water appeared to be influenced in several cases by the depth of the water, steepness of the bank and herbivory. Whilst the diversity of the shoreline vegetation appeared to be influenced by the nutrient availability, herbivory, wind and waves. Based on the knowledge on management options and environmental conditions, a management scheme was developed, indicating the preferred management for expansion of emergent vegetation and increasing the emergent vegetation diversity. A combination of natural water level fluctuations, occasional dry-outs, bank restoration and extensive grazing appeared to be most effective in promoting colonisation of open water by emergent vegetation and increasing the vegetation diversity