Influence of hydrological pathways on dissolved organic carbon fluxes in tropical streams

• Published in: Ecology and evolution 2017-01, Vol.7 (1), p.228-239
• Main Authors: Costa, Eline Nayara Dantas, Souza, Jéssica Carneiro, Pereira, Marilane Andrade, Souza, Marcelo Friederichs Landim, Souza, Weber Friederichs Landim, Silva, Daniela Mariano Lopes
• Format: Article
• Language: English
• Subjects: Agroforestry; Atlantic forest; Atmosphere; Basins; cacao; Carbon; Dissolved organic carbon; Ecosystems; Environmental changes; Fluxes; Forests; Hydrology; Inflow; Metabolism; Mud-water interfaces; Nutrients; organic matter; Original Research; Outflow; Overland flow; Plantations; Precipitation; Rainfall; Rainy season; Seasonal variations; Seasons; Soil dynamics; Soil water; Soils; Streams; Surface runoff; Throughfall; Tropical forests; Vegetation; Vegetation cover; Water balance; Water flow; Water inflow; Water outflow; watersheds
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.2543

Water flow pathways and water balance are fundamental components for understanding the dynamics of C in the soil/water interface of small basins. The objective of this study was to describe the seasonal variations and estimate the annual balance of dissolved organic carbon (DOC) by comparing two tropical microbasins (preserved forest—PF and cacao plantation—CP). Twenty‐one weekly collections were conducted from September to December 2012 and from April to June 2013. The calculation of the partial balance considered precipitation (P) as inflow and the stream as outflow. The samples were filtered and analyzed using a TOC analyzer. Overall, the DOC was higher CP compared with FP. The behavior of both venues showed that rainy season caused an increase in concentrations in the overland flow (OF) and in the stream, and a decrease in the precipitation (P) and in the throughfall (T). In the CP, the outflow and the soil were chiefly responsible for the high DOC concentrations in the stream, when compared to the PF, which is the result of constant OM decomposition. Soil composition contributes to the control of DOC consumption in each type of soil. The balances were negative in both microbasins, although losses were higher in the AFS (agroforestry systems) when compared to the PF, especially during rainy seasons (−8.98 and −3.05 kg ha−1 year−1, CP and FP, respectively). Thus, the high annual loss of DOC in the CP of the microbasins during the rainy season indicates changes in ecosystem metabolism due to the vegetation cover and to the interactions with the soil. The balances in both microbasins were negative, although losses were higher in the cacao plantation especially during rainy season. In the cacao plantation, the outflow and the soil were responsible for the high DOC concentrations in the stream, when compared to the preserved forest, which is the result of constant OM decomposition. Thus, the high annual loss of DOC in cacao plantation during the rainy season indicates changes in ecosystem metabolism due to the vegetation cover and interactions with the soil.