Our forest structure data are from the MDNR Forest Operations Inventory (OI), private industrial forest stand records, and timber stand cruises of private industrial and non-industrial forest stands undertaken during summer 2008 and early spring 2009.
The OIclassifies stands based on vegetation as well as management objectives and contains information such as stand type (e.g., aspen, northern hardwood, mixed swamp conifer, etc.), stand basal area (BA), and mean stand diameter-at-breast-height (DBH).
MDNR update OI data for individual stands on a 10-year rotation, so we adjusted the OI to account for changes in BA and DBH since last data collection for each northern hardwood stand.