Chemistry Matters: High Leaf Litter Consumption Does Not Represent a Direct Increase in Shredders' Biomass.

Changes in riparian vegetation can alter the input and quality of leaf litter in aquatic ecosystems, but the effects of these changes on litter fragmentation by invertebrate shredder communities in tropical streams remain poorly studied. The caddisfly genus Phylloicus Müller, 1880 (Trichoptera: Calamoceratidae) is highly abundant in Neotropical streams, representing a great part of shredder biomass, which uses the allochthonous litter as a food resource and for case-building. We investigated leaf consumption by Phylloicus sp. under different leaf conditioning (leached and unleached) and plant species (Eucalyptus grandis, Erythrina falcata, and Inga uruguensis). The effects of leaf conditioning and plant species were measured using microcosm treatments, with one free Phylloicus sp. larva per 2-l microcosm, and a decomposition control to correct for microbial decomposition. Our study suggests that phosphorus and caloric values of leaf litter are more important than leaf hardness and nitrogen in driving leaf consumption by Phylloicus sp. On the one hand, higher consumption was observed in treatment with unleached leaves than in leached leaf treatment due to higher nutrient concentration and caloric values on unleached leaves. On the other hand, Phylloicus sp. larvae preferred leached leaves for case building over unleached leaves, as leached leaves are less prone to the activity of the decomposing community, thus lowering the need for constant case renewal. Finally, high litter consumption is not necessarily converted into biomass by Phylloicus sp. larvae. In this sense, Phylloicus sp. larvae showed selectivity for resources with high caloric content for consumption and low caloric content for case-building.

Leaf litter mas loss rates and associated faun of tree species commonly used in neotropical riparian reforestation / Tasas de pérdida de masa de la hojarasca y fauna asociada en especies de árboles comúnmente utilizados en la reforestación de riberas neotropicales

A signature of globalization is the prevalence of exotic trees along reforested urban and rural riparian zones in the Neotropics, but little is known about the instream processing of its leaf litter. In this study, leaf litter breakdown rates were measured during 35 days using mesh bags within a reference headwater stream for seven exotic and three native tree species commonly used in urban and rural reforestation. Artocarpus altilis, Schefflera actinophylla and Terminalia catappa scored the highest mass loss rates (>85 %; mean life: t50.

Una de las señales más evidentes de la globalización es la prevalencia de especies de árboles exóticos a lo largo de las zonas ribereñas urbanas y rurales del Neotrópico, pero poco se sabe sobre el procesamiento de su hojarasca dentro de las quebradas. En este estudio se midieron las tasas de pérdida de masa de la hojarasca usando bolsas de angeo en una quebrada de referencia durante 35 días, para siete especies exóticas y tres nativas comúnmente usadas en la reforestación urbana y rural. Artocarpus altilis, Schefflera actinophylla y Terminalia catappa obtuvieron las mayores tasas de pérdida de masa (>85 %; vida media: t50.