Please use this identifier to cite or link to this item:
Title: Very high productivity of the C4 aquatic grass Echinochloa polystachya in the Amazon floodplain confirmed by net ecosystem CO2 flux measurements
Authors: Morison, James I.L.
Piedade, Maria Teresa Fernandez
Müller, Ewald K.H.
Long, Stephen Patrick
Junk, Wolfgang Johannes
Jones, Michael B.
Keywords: Aquatic Plant
C4 Plant
Carbon Dioxide
Carbon Flux
Primary Production
Amazonas State
Echinochloa Polystachya
Issue Date: 2000
metadata.dc.publisher.journal: Oecologia
metadata.dc.relation.ispartof: Volume 125, Número 3, Pags. 400-411
Abstract: Fluxes of CO2 and H2O vapour from dense stands of the C4 emergent macrophyte grass Echinochloa polystachya were measured by eddy covariance in both the low water (LW) and high water (HW, flooded) phases of the annual Amazon river cycle at Manaus, Brazil. Typical clear-sky midday CO2 uptake rates by the vegetation stand (including detritus, sediment or water surface) were 30 and 35 μmol CO2 (ground) m-2 s-1 in the LW and HW periods, respectively. A rectangular hyperbola model fitted the responses of 'instantaneous' (20- or 30-min average) net CO2 exchange rates to incident photosynthetic photon flux densities (PFD) well. Stand evaporation rates were linearly related to PFD. The major difference in CO2 uptake rates between the two periods was the larger respiration flux during LW due to the CO2 efflux from sediment, roots and litter. Integrated 20- or 30-min fluxes were used to derive relationships between daily CO2 and H2O vapour fluxes and incident radiation. The daily CO2 fluxes were almost linearly related to incident radiation, but there was evidence of saturation at the highest daily radiation totals. Annual productivity estimated from the daily model in 1996-1997 agreed closely with that previously estimated for 1985-1986 from a leaf-scale photosynthetic model, but were some 15% less than those derived at that time from biomass harvests. Both CO2 uptake and water use efficiency were comparable with those found in fertilized maize fields in warm temperate conditions.
metadata.dc.identifier.doi: 10.1007/s004420000464
Appears in Collections:Artigos

Files in This Item:
There are no files associated with this item.

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.