The Effects of Whole Tree Harvest on Soil Carbon and Nitrogen after 15 years

This study examines the effects of whole tree harvesting on soil carbon and nitrogen 15 years following harvest. Two specific questions were addressed: what is the duration and extent of C and N loss following harvest; how do C and N cycles in the forest floor and mineral soil behave after disturbance? Hubbard Brook Experimental Forest Watershed 5 (HBEF W5) was whole tree harvested (WTH) in 1983-84 and a quantitative pit approach was used to collect data in 1983 (pre-harvest), 1986, 1991 and 1998. The forest floor mass in 1998 was 97 Mg ha^-1, total C was 31 Mg ha^-1 and total N was 1.5 Mg ha^-1. The mineral soil mass in 1998 was 3100 Mg ha^-1, total C was 110 Mg ha^-1 and total N was 5.1 Mg ha^-1. The data suggests that after 15 years C and N pools of the forest floor and mineral soil are comparable to pre-harvest levels. However the effects on the individual organic horizons and mineral depth strata vary, with a significant decrease between 1983 and 1998 in the C pool for the combined Oi + Oe horizon and strong decreasing trends for the C and N pools of the 20+ depth strata and for Oie mass. The effects of harvest after fifteen years also differ by elevation group with the highest and lowest elevations losing nutrients, and the mid elevations retaining nutrients.