Quantifying biomass production for assessing ecosystem services of riverine landscapes

Society is increasingly in need of renewable resources to replace fossil fuels and to prevent resource depletion. River-floodplain systems are known to provide important societal functions and ecosystem services to mankind, such as production of vegetative biomass. In order to determine the potential of harvesting vegetative riparian biomass, the capacity of river systems to produce such biomass needs to be determined. We developed a method for quantifying the spatiotemporal development of annual biomass production in river floodplains. Vegetation specific growth rates were linked to a landscape classification system (i.e., the Ecotope System for National Waterways). Biomass production was calculated for floodplains along the three Rhine River distributaries (i.e., the rivers Waal, Nederrijn-Lek and IJssel) over a 15year period (1997-2012). During this period several large scale river management measures were undertaken to reduce flood risks and improve the spatial quality of the Rhine River as part of the Room for the River program. Biomass production decreased by 12%-16% from 1997 to 2012 along the three distributaries, which may be a side effect of flood mitigation. Almost 90% of the biomass produced was non-woody (e.g., grass/hay, reed, crops), which decreased along all three river distributaries due to the abandonment of production grasslands and the physical reconstruction of floodplains (e.g., creation of side channels). Woody vegetation, however, showed a slight increase during the 15year period likely owing to vegetation succession from shrubs to softwood forest.