Tufa barriers within the cascading Plitvice lakes hydrosystem are the sites that accumulate the considerable amounts of leaf litter. This thesis investigates the structural and functional differences of the macrozoobenthos colonized within the leaf litter bags of the two common, but differing plants at the Plitvice lakes - butterbur (Petasites spp.; aquatic vegetation; representing autochtonous leaf litter) and beech (Fagus sylvatica L.; woody vegetation; alochtonous leaf litter). Simultaneously, a leaf litter decomposition and the respective tufa deposition effects were investigated on four microhabitats, differing in flow velocity and tufa deposition rate. During this one-year study, the leaf litter bags were exposed to the natural tufa barrier conditions for one month. The results of this thesis suggest that the butterbur decomposes faster than the beech leaf litter. It was observed that the both leaf litter types fragment faster in the fast flowing microhabitats with high tufa precipitation rates. The flow velocity significantly affected the macrozoobenthos structure within the leaf litter bags. In the fast flow environments, regardless the leaf litter type, Simuliidae were the dominant taxon, while within the slow flow the macrozoobenthos composition depended on the leaf litter type – Ephemeroptera dominated within the beech, and Chironomidae within the butterbur leaf litter bags. Regarding the trophic structure of macrozoobenthos, at the fast flowing sites the passive filtrators prevailed, and at the slow flowing sites the most numerous were the detritivores, predators and shredders. Considering the rellatively low numbers of shredders within the leaf litter bags, it is likely that shredders do not considerably affect the leaf litter decomposition. As well, it is likely that because of the tufa deposition, leaf litter becomes unreachable and unsuitable as a macroinvertebrate food source.