Hs. Glazebrook et Ai. Robertson, The effect of flooding and flood timing on leaf litter breakdown rates andnutrient dynamics in a river red gum (Eucalyptus camaldulensis) forest, AUST J ECOL, 24(6), 1999, pp. 625-635
Comparisons of litter standing-stocks in low-lying and higher areas of the
floodplain and the effects of controlled flooding events on leaf litter dec
omposition and leaf litter nutrients were examined during autumn and winter
in a southeastern Australian river red gum (Eucalyptus camaldulensis) floo
dplain forest. The mean mass of total litter and some litter components was
significantly greater in autumn than in winter but there were few differen
ces in litter mass between low-lying flood runners and higher sites (1.5 m)
on the floodplain, regardless of season. Leaf decomposition was more rapid
in flooded areas than in non-flooded areas and was significantly faster in
autumn than in winter. In flooded leaves, concentrations of phosphorus and
nitrogen dropped rapidly during the first 3 days of each experiment, incre
ased to near original after 7-10 weeks and then decreased again. After 112
days of decomposition the C:N:P ratios of leaf litter increased, but this e
ffect was most marked for flooded leaves. Simple models of leaf litter dyna
mics indicated that leaf litter standing-stocks in low-lying flood runners
would be reduced by flooding, particularly during autumn. In contrast, mode
ls predicted a net gain in standing-stocks of leaf litter to be higher on t
he floodplain, particularly in autumn. Alteration to the seasonal timing of
floods by river regulation has probably decreased litter standing-stocks a
nd nutrients available in low-lying areas of the floodplain to support the
production of macrophytes and biofilms during winter and spring floods.