Assessment of riparian forest vegetation of rivers supporting the Prespa trout in the Transboundary Prespa Park Yannis Kazoglou 1, 4 , George Fotiadis 2 , Michael Vrahnakis 3 , Irene Koutseri 4 , Alain Crivelli 5 1 Municipality of Prespa, Lemos, Greece (present address), e-mail: ykazoglou@gmail.com 2 School of Forestry and Management of Natural Environment, Technological Educational Institute (TEI) of Kavala / Branch of Drama, Greece 3 School of Forestry and Management of Natural Environment, Technological Educational Institute (TEI) of Larisa / Branch of Karditsa, Greece 4 Society for the Protection of Prespa (SPP), Agios Germanos, Greece 5 Tour du Valat, Le Sambuc, Arles, France Abstract The QBR (Riparian Forest Quality) index and the RMP (Riparian Macrophyte Protocol) were used to assess habitat quality and inventory riparian forests in four rivers sustain- ing the endemic Prespa trout (Salmo peristericus). Total QBR index and total riparian cover (first component of the QBR index) values were found significantly higher in the upper parts of Brajcinska and Kranska rivers, while lower values were recorded in the upper parts of Agios Germanos river and Leva stream. Cover structure, cover quality and channel alteration (the other three components of the QBR index) did not differ significantly between the four watersheds. The greater presence of Fagus syl- vatica in the former rivers principally contributes to their increased total riparian area and riverbed cover compared to those of the two latter rivers. In the altitudes below 900 m.a.s.l., where gradients are gentle and human activities intense, vegetation types in all four systems change considerably with the participation of non-native species, while riparian area and riverbed cover are reduced. Key words: habitat quality, rapid assessment methods, macrophyte functional groups, Salmo peristericus conservation DOI: 10.2478/v10104-011-0042-3 Vol. 11 No. 1-2, 63-78 2011 Water observation and information systems for decision support 1. Introduction Riparian zones can be defined as semi-terrestrial transition zones found on the ecotone of aquatic and terrestrial ecosystems often affected by freshwater; they include the shores of any kind of aquatic for- mation (rivers, lakes, marshes, swamps, springs, etc.), floodplains, and riparian forests (forests with hydrophilous trees) (Zogaris et al. 2007). The latter, when developing along rivers and streams, are often named “riverine forests” to avoid confusion with similar forests growing on lakeshores. However, the terms “riparian forests/woodlands” are often used exclusively for river/stream ecosystems, thus & ECOHYDROLOGY HYDROBIOLOGY