Ecological Types of Wetland Buffer Zones – How ...

River ecosystems, along with riparian landscapes, are essential for maintaining and regulating natural cycles of water and nutrients between terrestrial and aquatic ecosystems. The key role is played in this respect by riverine wetlands, which can be regarded ashubs of biodiversity and ecosystem services. Yet, due to the large-scale modification of European rivers and wetlands andintensification of agricultural productions, these functions are seriously impaired. CLEARANCE project stresses the necessity of their protection and restoration, indicating wetland buffer zones (WBZ) as the solution. Although WBZsare commonly formed as strips of land adjacent to rivers, other shapes and locations can sometimes be more operational. These include specific groundwaterdischarge zones (e.g. fens)and floodplains. Moreover, when considering the role of in-stream nutrient removal processes, also whole section of a water stream can be regarded as a WBZ in reference to the lower reaches of the river or higher-order rivers.The role of WBZ in purifying water is strongly linked to eco-hydrological conditions and vary over time. In addition, therole of WBZ for nutrient removal by harvesting (and further recycling) will depend on the potential to promote high productivity and good access for agricultural machinery.CLEARANCE takes an operational approach to WBZ that stems from geomorphology, hydrology and landscape functioning. Spatial delineation of WBZs and the level of intervention necessary to optimise their ecosystem services depends on local natural conditions, specific nutrient loads and socio-economic constraints and opportunities. CLEARANCE proposes a hierarchical approach to WBZ classification, where the first level distinguishes between (i) WBZs as linear structures (i.e. section of the water course with its banks/shores) and (ii) WBZs as polygons (wide part of the water course valley).In practice, both types should preferably be combined to optimisenutrient removal and other functions of WBZs. However, the effectiveness of these two categories may vary a lot depending on regional physical circumstances (e.g. organic vs. mineral soils). Within each of these categories, CLEARANCE distinguishes sub-categories that differ with respect to physical constraints onpossible WBZ introductionunder different landscape circumstances. The considered WBZ types are: wetland banks/shores, two stage channel, meandering channel, undrained fen, rewetted fen, floodplain with organic soil, floodplain with mineral soil, oxbow.