Spatial Patterns of Organic Matter and Nitrogen in Forest Floor Soils of the Adirondack Mountains, NY.

We used Oe and Oa horizon samples collected from 42 plots in 2006 and archived samples from those plots collected in 1984 to characterize the spatial and temporal patterns in forest floor carbon (C) and nitrogen (N) in Adirondack northern hardwood, spruce-fir and pine forest plots. The amount of C and N in forest floor horizons was positively correlated with elevation in both data sets and forest floor horizons in spruce-fir and northern hardwood plots had significantly greater amounts of C and N than pine-dominated plots. There was no significant difference in the amount of C or N in either Oe or Oa horizons between the 1984 and 2006 in any forest type. There are well-documented gradients in atmospheric N deposition and foliar N across the Adirondack Mountains and plots receiving more atmospheric N input had more forest floor N in either 1984 or 2006. However, the amount of forest floor C was not correlated with the spatial pattern of N deposition, nor were there differences in forest floor C or N content between sampling dates related to the gradient of N deposition. In summary, natural characteristics of climate and stand type appear to influence the amounts of C and N in this set of Adirondack plots, but we have been unable to identify any influence the N deposition gradient may be having on spatial or temporal patterns of forest floor C or N.