Ecosystem Function

The effects of elevated nitrogen on the decay of woody litter have usually been measured by adding nitrogen compounds to soil, and the results are typically variable (Knorr et al., 2005), presumably because of the chemical and physical complexities of the soil-fungus-wood path, and differential effects on component processes involved in net wood decay. To analyse nitrogen effects on wood decay in the field, it would be more informative to measure the effect of the nitrogen content of decomposer mycelium on wood mass loss. P. velutina is a suitable organism for this because it can be established in woodland soils from pre-colonized wood blocks placed on the woodland floor (Boddy, personal communication). In this way, large numbers of even-aged mycelia from identical carbon resources can be set up for statistically valid assessment of nitrogen partitioning between mycelium, underlying soil and colonized wood. Using this approach, tests are in progress for a predicted correlation between mycelial intracellular nitrogen and wood decay.

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