Litter Decomposers

Primary above-ground inputs into grasslands (depending on the grazing regime) are in the form of plant litter, often forming a 'thatch' layer on the soil surface. Culture-based studies of grassland litter have tended to focus on ascomycetes (Hudson, 1968) but some basidiomycetes, usually forming small basidiocarps, are also abundant (e.g. Mycena spp. on grass litter, Galerina spp. on mosses), with others such as Crinipellis stipitaria, a possible latent invader, associated with more xerophytic grass tussocks but never soil (Warcup, 1951a; Parker-Rhodes, 1952). There is significant fungal translocation of N from soil to surface litter (Frey et al., 2000), and there are likely to be fungi which colonize and decompose litter but only fruit on soil. Microcosm studies using grass litter have demonstrated the effectiveness of Mycena spp. in lignin decomposition but also that decay rates are reduced when species compete (Deacon et al., 2006). In temperate grasslands, litter is rapidly incorporated into soil, largely through earthworm activity.

However, in African savanna termites, notably Macrotermes michaelseni, consume a high proportion of grass litter (Dangerfield and Schuurman, 2000). These eu-social insects cultivate lignolytic basidiomycete mutualists belonging to the genus Termitomyces in conspicuous nests, providing the fungus combs with partially digested faecal material and consuming the resulting hyphae (Chapter 9).

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