Leaf-litter breakdown in tropical streams: is variability the norm?

Boyero, Luz, Pearson, Richard G., Gessner, Mark O., Dudgeon, David, Ramírez, Alonso, Yule, Catherine M., Callisto, Marcos, Pringle, Catherine M., Encalada, Andrea C., Arunachalam, Muthukumarasamy, Mathooko, Jude, Helson, Julie E., Rincon, José, Bruder, Andreas, Cornejo, Aydeé, Flecker, Alexander S., Mathuriau, Catherine, M'Erimba, Charles, Gonçalves, Jose F., Moretti, Marcelo, and Jinggut, Tajang (2015) Leaf-litter breakdown in tropical streams: is variability the norm? Freshwater Science, 34 (2). pp. 759-769.

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Many forested headwater streams are heterotrophic ecosystems in which allochthonous inputs of plant litter are a major source of energy. Leaves of riparian vegetation entering the stream are broken down by a combination of biotic and abiotic processes and, in most temperate and boreal streams, provide food and habitat for dense populations of detritivorous invertebrates. However, tropical streams in different parts of the world show substantial variability in the number and diversity of leaf-shredding detritivores (hereafter detritivores). We used data obtained with standardized methods from multiple streams in Africa, the Americas, Asia, and Australia to test the hypothesis that this variability would lead to differences in the relative role of detritivores and microorganisms in the breakdown process.We also tested the hypotheses that variability in litter breakdown rates changes with litter type (native litter mixtures vs nonnative alder [Alnus glutinosa]) and is higher across regions within than outside the tropics. We found that litter breakdown rates were highly variable across sites, with no consistent pattern within geographic areas, although litter consumption by detritivores was negligible at several sites, all in America. Geographic patterns of litter breakdown also varied between litter types, with higher breakdown rates for alder than for native litter in most but not all regions.When litter breakdown rates at the tropical sites were compared to previously reported values from temperate and boreal regions, we found that differences in variability between tropical and temperate sites were inconsistent, with great differences among studies. Further global-scale studies will be needed to assess the extent to which latitudinal changes in the diversity and composition of microbial and detritivore assemblages contribute to variability in litter breakdown rates.

Item ID: 43925
Item Type: Article (Research - C1)
ISSN: 2161-9565
Keywords: decomposition, shredders, microorganisms, tropical streams, variability
Funders: National Geographic Society's Committee for Research and Exploration
Projects and Grants: NGS grant number 7980-06
Date Deposited: 10 May 2016 01:12
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060204 Freshwater Ecology @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960807 Fresh, Ground and Surface Water Flora, Fauna and Biodiversity @ 100%
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