Leaf litter breakdown in a Mediterranean stream characterised by travertine precipitation

Abstract

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.

Short-term responses of decomposers to flow restoration in Fossil Creek, Arizona, USA

“…However, that study emphasized the effect of leaf adhesion to travertine dams, which would both expose and hold leaves in place for rapid microbial and invertebrate decomposition. In this study, leaves at the downstream site became completely encased in travertine, potentially reducing leaf-surface availability to macroinvertebrates (Casas et al, 1994) or minimizing fragmentation (Casas & Gessner, 1999;LeRoy & Marks, 2006). This could have offset any increases in decomposition rates caused by flow restoration.…”

Organic matter decomposition by fungi in a Mediterranean forested stream : contribution of streambed substrata

“…The high C : N ratio measured in this substratum (Bernal et al 2003, Ostrofsky 1997) may be pointed out as the cause for the low mineralisation observed for this material. Slower breakdown of Platanus leaves than other indigenous Mediterranean leaf species (e. g: Populus nigra) (Casas & Gessner 1999) is probably caused by the higher lignin and other recalcitrant compounds content in the former (Ostrofsky 1997). In contrast, high CBH and P activities were recorded in biofilms on Populus nigra leaves, while the highest PO was measured on Alnus glutinosa biofilm.…”

Calcite deposition in karst waters is promoted by leaf litter breakdown andvice versa

“…It is a porous calcium carbonate deposit that develops in carbonatesupersaturated waters (Chafetz and Folk, 1984), where calcite crystals are deposited on immersed objects including organisms such as algae and mosses and animaloriginating structures (Riding, 1991;Carthew et al, 2003;Matonicˇkin Kepcˇija et al, 2006). Tufa deposits occur in karstic regions around the world but there are few studies of leaf litter processing in these habitats (Casas and Gessner, 1999;Carter and Marks, 2007;Compson et al, 2009).…”