Leaf litter breakdown in a Mediterranean stream characterised by travertine precipitation

1. Breakdown of four leaf species ( Platanus orientalis , Populus nigra , Salix atrocinerea , Rubus ulmifolius ) was studied in a Mediterranean second‐order stream characterised by abundant travertine precipitation, a history of fire in its catchment, and a recently revegetated alluvial corridor. 2. Compared to breakdown rates reported in the literature for congeneric species, breakdown of the four species was slow (k = 0.0024–0.0069 day −1 for the tree species, and 0.0103 and 0.0111 day −1 for Rubus ), in spite of high water temperatures, indicating that the travertine layer that quickly covered submerged leaves impeded decomposer activity and physical fragmentation losses. 3. Breakdown rates nevertheless differed between leaf species in a predictable manner, suggesting that the observed mass loss was largely due to biological processes. 4. The observed tendency towards increasing leaf nitrogen and phosphorus concentrations during breakdown suggests that microorganisms were actively involved in leaf breakdown; however, this interpretation must be viewed with caution because of potentially confounding effects by nutrients contained in the travertine layer. 5. Leaf breakdown of the three indigenous species was faster than that of the exotic species P. orientalis . Due to the recalcitrance of its leaves, the frequent use of Platanus in revegetation schemes following the destruction of indigenous vegetation by fire, exacerbates the negative effect of travertine precipitation on leaf breakdown and, by extension, energy flow in Mediterranean karst streams.