Changes in stand structure and fuel load have complicated the safe application of prescribed fire to ponderosa pine forests. Mechanical fuel reduction has become a necessary first step to reduce ladder fuels and tree density. A restoration project has been completed at Mount Rushmore National Memorial. Tree removal with chainsaw and hand piling of material was utilized. The objective of the project was to cut ponderosa pine trees with a dbh less than 10cm and pile it later for burning. The 65-acre Old Growth unit at Mount Rushmore was thinned late fall/early winter of 2007. Seven monitoring plots were established within the unit in 2007 before the thinning treatment was implemented.

The figure below displays number of stems by size class pre and post-thinning treatment. There was an inverse exponential curve of number of stems by size class prior to the thinning treatment. This thinning treatment significantly reduced ladder fuels, raised average crown base heights, and thus lowered the risk of crown fire.

The figure below shows a 98% decrease in pole density (> 2.5 & < 15.0 cm dbh) and a 23% increase in overstory density following the thinning treatment. Approximately 18 TPA remained in the pole class following the treatment.