Most of the data collected by the Forest Service in its long-term (1950s to present) silvicultural experiment (“compartment study”) on the PEF are maintained in a relational database. These data have been collected on permanent sample plots before, after, and at intervals between treatments.
Each experimental unit (compartment, or management unit [MU]) is about 20 acres in size; permanent sample plots cover 15% of the area and consist of nested 1/5, 1/20, 1/50 and 1/1000-acre circular plots. Tree measurements are taken on sample trees as small as 0.5 inches in diameter at breast height, and include species, diameter, and condition; seedlings have also been measured by species and height class since the 1960s. Since the 1970s, individual sample trees as small as 0.5-inches dbh have been assigned identification numbers and tracked over time.
Since the 1990s, a subsample of tree heights, crown widths, crown lengths and tree locations is taken; ground cover is recorded; and trees continue to be measured after they die. This intensive sampling has resulted in a wealth of data made available to researchers; more than one million tree measurements have been made.
Many of the data from the Forest Service’s long-term silvicultural experiment on the PEF is available through our Data Catalog. Requests for additional data should be directed to the Lead Scientist.