New publication: Source and sink carbon dynamics and carbon allocation in the Amazon basin
Christopher E. Doughty, D. B. Metcalfe, C. A. J. Girardin, F. F. Amezquita, L. Durand, W. Huaraca Huasco, J. E. Silva-Espejo, A. Araujo-Murakami, M. C. da Costa, A. C. L. da Costa, W. Rocha, P. Meir, D. Galbraith, Y. Malhi (2015) Source and sink carbon dynamics and carbon allocation in the Amazon basin Global Biogeochemical Cycles DOI: 10.1002/2014GB005028
Changes to the carbon cycle in tropical forests could affect global climate, but predicting such changes has been previously limited by lack of field based data. Here we show seasonal cycles of the complete carbon cycle for fourteen, one hectare intensive carbon cycling plots which we separate into three regions: humid lowland, highlands and dry lowlands. Our data highlight three trends: (1) there is differing seasonality of total NPP with the highlands and dry lowlands peaking in the dry season and the humid lowland sites peaking in the wet season; (2) seasonal reductions in wood NPP are not driven by reductions in total NPP but by carbon during the dry season being preferentially allocated towards either roots or canopy NPP; and (3) there is a temporal decoupling between total photosynthesis and total carbon usage or plant carbon expenditure (PCE). This decoupling indicates the presence of non-structural carbohydrates (NSC) which may allow growth and carbon to be allocated when it is most ecologically beneficial rather when it is most environmentally available.