Effects of Organic Matter Removal on Nitrogen and Carbon Leaching Fluxes in a Douglas-Fir Plantation.

The increasing interest in energy production from woody biomass may possibly affect the uptake of carbon and nitrogen in soil due to the removal of branches and foliage during the timber harvesting. This study aimed to look at the influence of organic matter removal during timber harvest. Specifically, how does the presence/absence of harvest debris (such as chips, branches) influence the accumulation of nutrients in the soil and, consequently, the final productivity of Douglas-fir plantation?  The experiment was installed in the Mackenzie River watershed, Eugene/OR, in a tree farm owned by Weyerhaeuser Company. The total area has 20 plots, with 1 acre in each plot. Three types of harvest were conducted in the different plots: bole-only harvest, total-tree harvest and total-tree harvest plus forest floor removal, as well as soil compaction in combination with these treatments. Lysimeters at the depths 20-cm and 100-cm depth were installed in the treatments in order to measure the concentration of nutrients leached along the soil profile. The measurements have been taken once a month. Samples will be analyzed for soil alkalinity, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), as well as macronutrients and micronutrients. There are no data available at the moment.