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Effects of stump removal on bulk density and nitrogen content of forest soils Removal of infected stumps and fertilization after timber harvest has been used to reduce root rot infection in the succeeding forest rotation. However, concerns about the effects of heavy equipment and the large degree of disturbance of forest soils from stump removal has limited application of this method.This research examines soil bulk density, soil and forest floor total nitrogen levels, and forest floor mass taken 20 years after stumping operations performed at five locations in the Pacific Northwest to control laminated root rot (Phellinus weirii (Murr.) Gilb.) in stands regenerated with Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Results show that on these sites the soil bulk density increases caused by stumping, while long lasting, are not severe enough to limit tree growth or discourage the stumping practice. A continuing deficit caused by the stumping procedure was noted after 20 years in mineral soil total nitrogen and carbon levels and forest floor depth. The stumped areas show a nitrogen concentration that is 20% lower than the non-stumped areas. Soil carbon concentrations were 24% lower and the forest floor depth was 24% lower in the stumped areas. This reduction in the organic component of the soil is a concern for nutrient cycling and long term productivity on poor sites. Disturbance of the soil and forest floor has been shown to lead to similar reductions in studies of mechanical site preparation. Mitigating soil and forest floor disturbance should be a goal when utilizing the stump removal practice. |