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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Urban Ecology I
FUNGAL BIOMASS ON DECOMPOSING TULIP-POPLAR LEAVES IN SUBURBAN STREAMS.
S. Herbert and J.L. Meyer. Institute of Ecology, University of Georgia, Athens, Georgia, USA 30602
Humans alter stream ecosystems in a variety of ways, and adverse effects can be especially intense in suburban watersheds. Fungi are an important component in determining leaf breakdown, which is an essential stream ecosystem function. We analyzed fungal biomass on decomposing tulip–poplar leaves (Liriodendron tulipifera L.) in 4 suburban streams and 2 streams draining mixed–use watersheds near Atlanta, Georgia. Relationships between fungal biomass (measured as ergosterol) and physical factors, leaf breakdown, and nitrate, ammonium, and soluble reactive phosphorus concentrations were examined. Fungal biomass stabilized at peak levels after 4 weeks and did not vary significantly from this level for up to 10 weeks. Average fungal biomass (as mg dry mass [DM] per g ash free DM [AFDM]) of aquatic hyphomycetes ranged from 17 mg DM/g AFDM to 28 mg DM/g AFDM over this time period. These values are in the lower range of fungal biomass seen in other studies in forested watersheds on tulip–poplar leaves. There were no significant differences in fungal biomass between suburban and mixed–use sites. Fungal biomass was positively correlated with nitrate concentration, but not correlated with leaf breakdown rates, suggesting that other factors are stronger determinants of breakdown in these streams.
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