Leaf breakdown in an Atlantic Rain Forest stream

Abstract

The hypothesis of this study was that colonizers in decaying leaf litter prefer native species (Erythrina verna) to exotic ones (Eucalyptus camaldulensis and Protium heptaphyllum). Therefore, native species are expected to show higher breakdown rates, increased biomass, richness and density of invertebrate species, and increased biomass of decomposer fungi. Breakdown of leaf litter from these three species was assessed in an Atlantic Rain Forest stream. Four samples were collected during a period of 90 days and washed on a sieve to separate the invertebrates. Then, a series of leaf disks were cut to determine ash-free dry mass and fungal biomass, and the remaining material was oven-dried to determine the dry weight. Eucalyptus camaldulensis and E. verna showed higher breakdown rates than P. heptaphyllum, due to differences in leaf physical and chemical characteristics. The harder detritus (P. heptaphyllum) broke down more slowly than detritus with high concentrations of labile compounds (E. camaldulensis).The density of the invertebrates associated with detritus increased with time.There were no differences in density, taxonomic richness or biomass of invertebrates among the leaf types, which indicated that the invertebrates did not distinguish between exotic and native detritus. Fungal colonization varied among samples; E. camaldulensis showed the lowest ergosterol concentrations, mainly due to a high concentration of total phenolics. The detritus with the highest hardness value was colonized most slowly by fungi. These results showed that leaf breakdown in Atlantic Rain Forest streams could be affected either by changes in riparian vegetation, or by becoming more savanna-like process due to climate change.

Leaf breakdown in a natural open tropical stream

“…Leaching occurs throughout the decomposition process (Gessner et al, 1999); however, in the present study, the reductions in total polyphenols and condensed tannins occurred slowly, particularly during the first month of incubation, due to the hardness of the leaves, which protects against water loss (Edwards et al, 2000). However, these results are inconsistent with several studies in tropical streams (Albariño and Balseiro, 2002;Schlickeisen et al, 2003;Ardón and Pringle, 2008), although they agree with the studies of Gonçalves et al (2012aGonçalves et al ( , 2012b on native detritus in Brazilian savanna streams.…”

The Effects of Spatial Scale on Breakdown of Leaves in a Tropical Watershed

“…Therefore, the chemical characteristics of detritus determine the speed of processing (primarily at local scales), showing that leaf breakdown rates increase with quality and palatability [6], [7], [35], [39]. Detritus quality is of lower importance when if it is observed at different scales.…”

“…E. cloeziana has elevated amounts of labile compounds, facilitating the activity of bacteria (rapid life cycles) that use compounds derived from the leaching of the leaves of labile detritus as their preferred resource [68]. These bacteria could be important during leaf breakdown and not only, as observed by several authors, at the early stages of the process [6], [13], [35]. However, this pattern is rarely observed in tropical streams.…”

Chemical change of leaves during breakdown affects associated invertebrates in a subtropical stream

“…The leaching of soluble compounds may account for considerable loss of leaf initial mass and can be responsible for greater reduction of secondary compounds concentration (Gonçalves et al, 2012). Microbial colonization (especially fungi) enhance leaf breakdown by macerating and metabolizing the leaf tissue and indirectly increases the concentration of leaf nutrients (e.g.…”