Carbon Flow From Lignocellulose: A Simulation Analysis of a Detritus‐Based Ecosystem

Abstract

A simulation model is used to predict the fate of carbon derived from lignocellulose in the food web of a marsh community in the Okefenokee Swamp, Georgia. The model, constructed from empirical work spanning a 6—yr period, predicts the role of lignocellulose—derived detritus in supporting secondary production in this ecosystem. Although Carex walteriana lignocellulose is the dominant product of primary production in this marsh and the dominant source of detritus, the model predicts that it may not be quantitatively important in the support of tropic groups other than bacteria and protozoa. The efficiency of transfer lignocellulosic carbon through the microbial loop is low, and overall only 8% of the carbon used by bacteria and fungi is predicted to be ingested subsequently by metazoans. An average of 32% of the bacterial biomass in the marsh water and sediments is predicted by the model to be produced at the expense of lignocellulosic carbon, whereas <10% of the biomass of larger detritivorous animals can be traced to carbon from lignocellulose. Thus in this marsh ecosystem, detritus food webs based on other, less abundant, sources of detrital carbon, or perhaps classical plant—herbivore food webs, are more likely to be the major source of carbon for metazoan production.

Microbial biomass, growth, and respiration associated with submerged litter of Phragmites australis decomposing in a littoral reed stand of a large lake

“…The recognition of fungi as an important decomposer assemblage of submerged Phragmites australis litter is at partial variance with previous reports, which have postulated an equal or greater role of bacteria in the decomposition of emergent macrophytes (e.g., Mason 1976, Benner et al 1986, Moran et al 1988. Using selective inhibitors, Mason (1976) attempted to separate the respiratory activity of bacteria and fungi associated with submerged P. australis leaf litter.…”

Tracing of Peroxidase Activity in Humic Lake Water

“…cellulosic matter and HS have been recognized as an important part in microbial carbon fluxes [1,6,7,[13][14][15][16][17][18][19]. However, due to its polymeric nature refractory dissolved organic matter (RDOM) has to be cleaved extracellularily to oligo-and monomeric compounds before it can be assimilated by aquatic microbes.…”

Modeling bacterial utilization of dissolved organic matter: Optimization replaces Monod growth kinetics

“…No models exist to predict bacterial C yield in natural environments, although such models have been developed for bacterial axenic cultures growing on defined medium (Heijncn and van Dijken 1992). As a result, most microbial food web models define bacterial yield as a constant, and either do not incorporate C and N coupling (Pace et al 1984;Moran et al 1988) or base such coupling on elemental balano:s only (Fasham ct al. 1990;Taylor and Joint 1990;Moloney and Field 199 1).…”