Leaf bags and natural leaf packs: Two approaches to evaluate river functional characteristics

An extensive knowledge of the functional characteristics of rivers is of ba sic importance to develop precise management plans with specific aims, e.g. to rehabilitate riparian ecotones or increase the retention capacity of st reams. In this study man-made leaf bags (LB) and natural leaf accumulations (NLP) were used. The first method was useful in calculating breakdown rate s and the second one in understanding the effective litter composition, whi ch does not always reflect the composition of the riparian canopy. The asse mblages of macroinvertebrate colonizing both LB and NLP were divided into f unctional feeding groups and compared. Are both methods (Leaf Bags and Natural Leaf Packs) necessary and complemen tary to analyse the functional characteristics of an upland river? The stud y was carried out in three different sites on the upper reaches of the Adig e River. The breakdown rates were very similar in all three study sites but litter quality and quantity were very different. Although, in the two uppe r sites, the composition of invertebrates colonizing LB and NLP was the sam e, abundance and biomass values coincided only in the first stage of the co lonization process of LBS. In the third site no invertebrates using litter as a trophic resource were found. Both NLP and LB methods are needed in the evaluation of rehabilitation prog rams as they take account of the different aspects of the dynamics and the composition of CPOM.