The nitrogen budget of Thoreau's Bog.

Abstract

Dinitrogen fixation and atmospheric deposition are the dominant N sources to Thoreau's Bog, contributing c.1.0 and 0.7 g m-2 yr-1, respectively. Denitrification must compete with nitrate uptake and the reduction of NO3- to NH4+; the latter process accounts for the fate of c.25% of nitrate input. Gaseous ammonia is not an input, but appears to be lost in small amounts from the bog surface. Organic N is deposited into the peat by plants, a third 'permanently' deposited, and the balance recycled through mineralization and uptake. Compared to other ecosystems, the bog processes nitrogen in a parsimonious fashion. Annual fluxes are small compared to total N stored in the ecosystem, and nearly 80% of annual N input is retained with the system.-Author