Overstory tree and regeneration data from the "Silvicultural Effects on Composition, Structure, and Growth" study at Penobscot Experimental Forest: 3rd edition

This data publication contains all available data collected from 1952 through 2023 at the Penobscot Experimental Forest in Bradley and Eddington, ME, under the study plan: FS-NRS-07-08-01 "Study Plan: Silvicultural effects on composition, structure and growth of northern conifers in the Acadian Forest Region: Revision of the Compartment Management Study on the Penobscot Experimental Forest". This third edition comprising data previously published and data collected since the publication of the second edition in 2015. Data were collected on a series of permanent sample plots distributed across management units receiving various silvicultural treatments. Plot data are available in eight separate data sets. Overstory tree and sapling data include tree species, condition (e.g., merchantability status and cause of mortality), and diameter at breast height of living and dead trees, 1952 to 2023. Regeneration data include tree seedling species, presence, and count by height class, 1964 to 2023. Tree location data include the distance and azimuth from plot center of a subsample of trees, 2003 to 2023. Height and crown radius data include total height, height to crown base, and crown radius measurements for a subsample of live trees, 2003 to 2020 (heights) and 2003 to 2017 (radii). Understory vegetation and substrate data include percent cover by substrate and vegetation categories, 2003 to 2023. Standing deadwood data include heights and bark condition of standing snags, 2013 to 2020. Permanent sample plot location data include geospatial coordinates for permanent sample plots, 2018 and 2020. Depth to water table data include minimum, maximum, and average water table depths at three drainage thresholds at each plot location, 2023. Future inventories are planned for this study indefinitely.
The primary objective of the long-term silvicultural study, called the Compartment Management Study (CMS), conducted by the USDA Forest Service at the Penobscot Experimental Forest (PEF) is to quantify tree and stand response to silvicultural treatment. Response variables include regeneration, species composition, and tree and stand growth, productivity, and quality. Data provide information about natural and human disturbances and their effects on forest stand dynamics. A secondary objective of the study is to provide a variety of forest structures at one location to be used as the framework for short-term experiments in ecology and silviculture.
A number of revisions have been made to this long-term study over time, including but not limited to changes in silvicultural prescriptions (e.g., target residual basal areas, tree size thresholds for removals, and species composition goals), sampling protocols (e.g., numbers and sizes of sample plots, tree species and condition codes, and frequency of inventory), and response variables (e.g., overstory tree attributes, regeneration, understory vegetation and substrate, and deadwood). The first edition of this data publication was published in 2012 (https://doi.org/10.2737/RDS-2012-0008). The second edition (https://doi.org/10.2737/RDS-2021-0008-2), published in 2015, included two years of additional data as well as corrections to data errors. This third edition includes nine additional years of overstory tree, regeneration, stem mapping, and understory data (through 2023), six additional years of tree height and crown data (through 2020 and 2013, respectively, when collection of those data was paused), and updated values for plot-level depth to water table. A protocol for collecting additional data on standing deadwood (total height, height to base of splinter, and bark condition) was in use for eight years (2013 through 2020), and these data have been included as a new data table in the third edition. Corrections to data have also been addressed in this version. Supplemental materials and metadata have been revised to reflect these changes, and a list of changes between the first, second, and third editions are located in the supplemental files (available with the full data publication download). We strongly recommend that users read the study plans and accompanying documentation provided with the full data publication download, and familiarize themselves with the methodology references before proceeding with data summary or analysis.