An analysis of litter nitrogen dynamics using artificial soils across a gradient of forest soil disturbances

Abstract

The release of nutrients from a standard litter is often assumed to be solely a function of its decomposition rate. We tested whether nitrogen release would also be influenced by soil attributes affected by disturbance, such as interactions with soil microflora. Changes in nitrogen contents of decaying litter (Populus balsamifera) were compared across soil compaction and organic matter removal treatments in central British Columbia, using artificial materials to isolate litter bags from contact with forest floors or mineral soil. After 30 mo, nitrogen content of litter was only slightly higher on artificial soils than actual soils, suggesting that most nitrogen had been lost by leaching. A significant interaction, however, was detected in leaf nitrogen content between organic matter removal and soil compaction treatments that was not found on the artificial soils. This difference in nitrogen release led to a range in C:N ratios of 28 to 32 (from an initial C:N ratio of 52) for leaves at 1.5 g (70% mass loss). The differences in nitrogen release were relatively small and will perhaps be less important than other effects of soil disturbance (such as changes in litter quality) on nitrogen cycling. Key words: Nitrogen, decomposition, litter bag, translocation, compaction, forest floors