Dissolved organic carbon fluxes in precipitation, throughfall and overland flow in a riparian forest in Southwestern Amazonia (Rondônia, Brazil)
Leite, DCEN/UNIR, firstname.lastname@example.org
Krusche, CENA/USP, email@example.com
Cabianchi, DCEN/UNIR, firstname.lastname@example.org
Ballester, CENA/USP, email@example.com
Victoria, CENA/USP, firstname.lastname@example.org
Richey, University of Washington, email@example.com
Souza, DCEN/UNIR, firstname.lastname@example.org
Xavier, DCEN/UNIR, email@example.com
Neill, MBL, firstname.lastname@example.org
Deforestation to pasture is the main type of land use change in Amazonia. In spite of various nutrient cycling studies comparing different land cover (i.e. pasture vs. intact forest), little is known about the fluxes of dissolved organic carbon (DOC) derived from precipitation, throughfall and overland flow in these tropical riparian forest ecosystems. In this study we sampled rainfall, throughfall and overland flow in a riparian fragment of the Urupá River - Rondônia, Brazil, from November 2004 to May 2005. Samples were analyzed for pH, electrical conductivity and DOC concentrations. Results showed that all the samples were acidic, with mean pH of 5.691, 5.818 and 4.520, respectively. Mean DOC concentration in precipitation was 164.8 microM. After washing the forest canopy (throughfall), this value increased to 584.0 microM. However, after moving over the forest floor (overland flow), concentrations showed a decreased, although not statistically significant, to 563.3 microM. Seasonal variations in DOC concentrations were very similar in throughfall and overland flow, increasing after the establishment of the rainy season (after March). The study showed that the concentrations of DOC in precipitation and throughfall that end up as overland flow are not affected by Ultisol soils, and represent additional sources of organic matter to the adjacent river.
Key Words: Amazonia dissolved organic carbon, riparian forest, precipitation, throughfall, overland flow.