Samenvatting

River-floodplain systems, located in the lower gradients of the river, are highly dynamic and biodiverse systems. Despite the ecological and economic importance of river systems, thesesystems are threatened. There is a need for appropriate management to restore and sustain biodiversity across the river system. Therefore, studies have tried to describe river functioning holistically. This has resulted in several theoretical river ecosystem concepts. A major concept that describes ecosystem functioning and structure in floodplains is the Flood Pulse Concept. Although this concept was successfully applied to several tropical and temperate rivers, the Flood Pulse Concept is not completely relevant to the Biebrza Lower Basin, a peat mire floodplain system.Here, in order to investigate whether other concepts describe, explain and support the functioning of river-floodplain systems in the Biebrza River, the applicability of three other riverecosystem concepts (Process Domains Concept; PDC, Riverine Ecosystem Synthesis; RES and River Wave Concept; RWC) to the Biebrza river-floodplain system is described. Literaturedata on both the Biebrza Lower Basin and the three concepts was used. Hypotheses were derived from the concepts, which were tested on the Biebrza river-floodplain system.