Metrics for comparing stand structure and dynamics between Ecological Reserves and managed forest of Maine, USA

A data set of common forest metrics was prepared using inventory data from Ecological Reserves in Maine, northeastern USA. An Ecological Reserve is generally defined as an area where timber harvesting does not occur and natural disturbance events are allowed to proceed without significant human influence. Beginning in the early 2000s, permanent, long term monitoring plots were established in Reserves across Maine. To date, 50 Reserves occupying approximately 70,820 ha with a total of 1,103 monitoring plots comprise Maine's Ecological Reserve System. A goal of the Ecological Reserve Monitoring program is to remeasure plots every 10 years and about half of the plots have been remeasured since the initial inventory. Stand metrics were calculated for both monitoring rounds and include: live tree basal area, live tree density, large (diameter at breast height, dbh ≥40 cm) and very large (dbh ≥51 cm) live tree density, standing dead tree density, large (dbh ≥40 cm) and very large (dbh ≥51 cm) standing dead tree density, total and large (diameter at transect intersect ≥40 cm) downed coarse woody debris volume, as well as various stand dynamic metrics. For comparison, the same metrics were computed for managed forests in Maine using permanent plot data from the US Department of Agriculture, Forest Service, Forest Inventory and Analysis (FIA) Program. Information on Ecological Reserve monitoring plots includes Ecological Reserve name, forest-type group, geographic location, elevation, slope, aspect, and harvest history. This data should prove invaluable for assessing and evaluating long-term changes in Ecological Reserves across the broad ecological/climate zones that are present in Maine. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper. These data are freely available for non-commercial scientific use.