Gijsbert Cirkel doctorate
Relation between water and vegetation in wet grasslands
Wet meadows fed by seepage water, such as bluegrasslands, are considered the crown jewels of biodiversity in the Netherlands. Over the past century, however, they have significantly declined, both in terms of their surface and their botanical quality. In his doctoral work at Wageningen University, KWR researcher Gijsbert Cirkel provides an integrated insight into the hydrological and biogeochemical relations between seepage water, infiltrating precipitation water and vegetation patterns. Based on this insight, managers can take measures to contribute to the preservation of these meadows.
Today, low-productive meadows can only be found in small, protected natural areas, frequently isolated within an intensively-worked agricultural landscape. The high biodiversity of these meadows is explained by the upward seepage of clean and base-rich groundwater. This results in relatively high and stable groundwater levels and, combined with a limited quantity of infiltrating rainwater, in small-scale water-quality gradients in the ground. This creates large variations in the ground over very short distances, so that plant species with different habitat preferences nonetheless occur right next to each other.
Practically everywhere in the Netherlands, intensive drainage in agricultural areas and increased groundwater abstraction have resulted in decreased seepage intensity and the increased influence of infiltrating rainwater in the ground in seepage-dependent nature reserves. Biodiversity has, as a consequence, diminished
To restore the full botanical glory of seepage-dependent ecosystems, water management measures have to focus on restoring the seepage intensity and the high groundwater levels, in close concert with the restoration of small-scale abiotic gradients. This calls for tailored measures which, according to Cirkel, must be founded on knowledge of the hydrological and biogeochemical processes in these areas. His doctoral research offers insight into the relations between seepage water, infiltrating precipitation water and vegetation patterns, and can contribute to a proper assessment of the ecohydrological effects of water management actions, of climate change and of the upward seepage of polluted groundwater.
© 2017 KWR Watercycle Research Institute
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