Long-term effects of stump removal to control root rot on forest soil bulk density, soil carbon and nitrogen content

Removal of stumps and fertilization after harvesting have been proposed to reduce root diseases in succeeding stands. Potential impacts such as compaction and loss of soil C or N could limit the use of this technique. This research examined forest soils in five Pacific Northwest stands 22–29 years after stump removal and fertilization with N. Results show that small long-term soil bulk density increases caused by stump removal are not likely to either limit tree growth or discourage the use of stump removal to reduce root rot. However, an extended decrease was noted in mineral soil total N and C and forest floor depth caused by stump removal. The stumped areas show a mineral soil nitrogen concentration that is 20% lower than the non-stumped areas. Mineral soil carbon concentrations were 24% lower and the forest floor depth was 24% lower. A non-significant trend of lower foliar N was also observed with stump removal. These results were consistent in all five soil types. This reduction in the organic component of the soil may be a concern for nutrient cycling and long-term productivity on poor sites.