Forest Structure Affects the Stoichiometry of Periphyton Primary Producers in Mountain Streams of Northern Patagonia

MODENUTTI, B.E.; MODENUTTI, B.E.; BALSEIRO, E.G.; BALSEIRO, E.G.; MARTYNIUK, N.; MARTYNIUK, N.

ECOSYSTEMS (NEW YORK. PRINT)

SPRINGER

Lugar: Berlin; Año: 2016 vol. 19 p. 1225 - 1239

1432-9840

Riparian zones are major components of streamecosystems that influence the physical, chemical,and biological parameters. In particular, the distributionof vertical foliage and the structure ofriparian vegetation determine light availability incanopied streams. Here, we analyzed how foreststructure will modify light availability and thusaffect primary producers? photosynthetic parametersand the periphyton stoichiometry of mountainstreams. We carried out field sampling in fourstreams with different canopies located in theNorth-Patagonian Andes and conducted a fieldexperiment in which light conditions weremanipulated for four months. Then, we linked ourresults to qualitative climate change scenarios forNorth-Patagonian forest predicting how future climatechange will affect primary producers andperiphyton stoichiometry in low-order streamsthrough modifications in the structure of canopiedzones. Finally, we found that biomass, photosyntheticparameters and the elemental content ofperiphyton exhibited a bell-shaped relationshipwith light availability which was, in turn, dependenton canopy cover. These trends are characterizedby an increase from low light up to250 lmol m-2 s-1 and a decline when light is over750 lmol m-2 s-1. Thus, intermediate light resultedin optimal conditions for primary producers?photosynthesis; however, these intermediatecanopied zones are predicted to decrease in thefuture. Therefore, we predict changes in streamecosystem stoichiometry due to variations in primaryproducers? photosynthesis, and, consequently,periphyton elemental composition as anoutcome of forest structure modifications due toclimate change.