A. I. Robertson, Stuart E. Bunn, Paul I. Boon, Kate F. Walker
Tóm tắt
This paper reviews research on fluxes of carbon in Australian floodplain
rivers. Except where cover is absent, and in-stream gross primary production
is >1 gC m–2 day–1
and ratios of production to respiration are >1, riparian sources dominate
carbon pools in catchment streams. On floodplains, primary production by river
red gum (Eucalyptus camaldulensis) forests is ~600
gC m–2 year–1. Total
primary production by aquatic macrophytes and biofilms in floodplain wetlands
is >2500 gC m–2
year–1 and >620 gC
m–2 year–1,
respectively. Large pools of particulate organic carbon (POC) exist on
floodplains as litter (>500 gC m–2) and coarse
woody debris (~6 kgC m–2). Floods may release
50 gDOC m–2 from leaf litter. Export of this DOC
(dissolved organic carbon) may be substantial relative to autochthonous
production in river channels. Sediments deposited on floodplains during large
floods represent a substantial sink of riverine POC (up to 280 gC
m–2). Bacteria are responsible for rapid
decomposition of DOC and POC in floodplain wetlands (sediment respiration and
methanogenesis, both ~1 gC m–2
day–1). Flow and its interaction with
geomorphology control carbon fluxes in rivers. Decreased inputs of floodplain
carbon, following river regulation and physical disturbances to catchments and
floodplains, may have resulted in many Australian rivers being dominated by
algal production.
