Landscape variation in nitrogen mineralization and nitrification.

The N Michigan forests studied were an oak ecosystem primarily associated with glacial outwash features and 2 sugar maple Acer saccharum ecosystems that occurred on morainal landforms but differed in the diversity and abundance of ground flora species. Litter was collected from all ecosystems during autumn. Litter production, N returned to the forest floor, and net mineralization differed by a factor of 2 between the oak and sugar maple ecosystems. The species-rich sugar maple ecosystems exhibited a 4-fold increase in potential nitrification compared with the species-poor sugar maple ecosystem. Nitrification was virtually absent in the oak ecosystem. The distribution of ecosystems could be used to predict differences in potential mineralization and nitrification. Areas susceptible to nitrate loss following intensive forest management practices may be related to the occurrence of plant associations. -from Authors