Carbon dynamics in small tropical catchments under preserved forest and cacao agroforestry systems

• Published in: Agroforestry systems 2021-12, Vol.95 (8), p.1647-1659
• Main Authors: da Costa, Eline Nayara Dantas, de Souza, Jéssica Carneiro, Pereira, Marilane Andrade, de Souza, Marcelo F. Landim, de Souza, Weber F. Landim, da Silva, Daniela Mariano Lopes
• Format: Article
• Language: English
• Subjects: Agriculture; Agroforestry; Alkalinity; Biomedical and Life Sciences; Carbon; Carbon dioxide; Catchments; Dissolved inorganic carbon; Fluxes; Forestry; Hydrology; Inland waters; Life Sciences; Metabolism; Organic matter; Rainfall; Soil solution; Stream water; Streams; Surface runoff
• ISSN: 0167-4366; 1572-9680
• DOI: 10.1007/s10457-021-00671-1

Inland waters such as streams that receive carbon from terrestrial landscapes usually have a net heterotrophic metabolism and emit significant amounts of CO 2 to the atmosphere. This research aims to analyze the role of hydrological routes to transport the dissolved inorganic carbon (DIC) and p CO 2 concentration in stream water and describe their dynamics by comparing two small catchments under tropical preserved forest (TPF) and cacao agroforestry system (CAS) during distinct rainfall regimes. The sampling occurred weekly (for twenty-one weeks) from September to December 2012 and from April to June 2013. The p CO 2 in stream water (SW) was calculated using total alkalinity and pH data. The DIC of soil solution (SS) and surface runoff (SR) were measured through a TOC analyzer. The SS and SR have different patterns of influence on the DIC concentrations in the streams. The DIC concentrations were higher in CAS than in TPF. The p CO 2 in CAS was eight and sixteen times higher than TPF in dry and rainy periods, respectively. Fluxes in both areas were significantly elevated during the rainy period compared to the dry period. DIC fluxes were higher in CAS than TPF during both periods (CAS: 1.72 and 19.1 kg ha −1  year −1 and TPF: 0.10 and 2.82 kg ha −1  year −1 to dry and rainy periods, respectively). Based on these results and previous studies involving C fluxes, it is possible that the cacao agroforestry system promotes changes in stream water metabolism, considerably raising p CO 2 and DIC concentrations, probably owing to organic matter created by cacao vegetation without management.