IDENTIFYING CHANGES IN TREE FORM FOR HARVESTED PONDEROSA PINE IN THE BLACK-HILLS

Recent underestimates of total volume for timber sales in the Black Hi lls National Forest prompted analysis of two felled ponderosa pine (Pi nus ponderosa Laws.) data sets that were collected approximately 10 ye ars apart. Though neither data set collected was a representative samp le of the Black Hills, both were similar in terms of diameter at breas t height and total height. We investigated several methods for assessi ng differences in tree form and applied them to these two data sets. U nder the assumption that these two data sets were representative of ha rvested trees in the Black Hills (which may be incorrect), we conclude d that the average tree form of harvested ponderosa pine has changed s ignificantly in the last 10 years. This conclusion highlights the impo rtance of using representative data in model building.