How does forest productivity influence river export of plant wax?
Abstract
How much carbon, fixed in tropical forest photosynthesis, is exported by rivers? From the large biomass held in tropical forests only a small component enters rivers for export. The exported fraction of tropical forest production represents the component removed from the rapid photosynthesis-respiration cycle, with potential for long-term sequestration in downstream sediments. Along the journey downstream, the transported organic matter may be lost to respiration, or stored in deposits before remobilization and later export. Discriminating between carbon sources in rivers presents a challenge to answering the question posed. But, plant waxes are specific tracers of plant biosynthesis that we use to identify sourcing and transport by the river, and that represent a resilient component with sequestration potential. Thus, we quantify the fraction of fresh forest production that goes into plant wax in a series of 9 forest plots in the Madre de Dios River catchment, Peru and set this in the context of catchment scale NPP estimates. Downstream sampling in two seasons captures the suspended particulate load of plant waxes in transit. Paired analyses of carbon and hydrogen isotopes allow for source apportionment by elevation allowing insight into catchment integration processes. Downstream concentrations of plant wax n-alkanes in river are related to discharge to yield estimates of the instantaneous catchment export flux in two contrasting seasons. Ultimately we seek to constrain the flux of plant wax exported by the river, and to estimate what fraction of forest NPP makes that journey from land to sea.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.B23F..01F
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0420 Biomolecular and chemical tracers;
- BIOGEOSCIENCESDE: 0424 Biosignatures and proxies;
- BIOGEOSCIENCES