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15N NATURAL ABUNDANCE AND 15N LABELLING STUDIES IN FOREST ECOSYSTEMS
Citation:
Nadelhoffer, K. AND B. Fry. 15N NATURAL ABUNDANCE AND 15N LABELLING STUDIES IN FOREST ECOSYSTEMS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-94/160.
Description:
The relative amounts of the two stable isotopes of Nitrogen (N), 15N, and N, vary predictably in soils and plant tissues of forests and other non-cultivated ecosystems. light fractionations, or discriminations against the heavier N isotope, that can occur as N cycles through vegetation, soils and microbial biomass act over the long term to deplete vegetation and litter of 15N and to enrich humus in 15N. n this chapter, we show that 15N natural abundances can be used to make inferences about 1) rates and patterns of N cycling, 2) the relative importance of N inputs versus soil processes in supplying N for plant uptake, 3) retention of N by forests and 4) forest ecosystem health. e also discuss uses of 15N-labelling ecosystem-scale experiments on whole forests. uch experiments offer possibilities for checking and improving estimates of N fluxes within and N losses from forests.