The University of Maryland, Baltimore County (UMBC) Forest Structure sites are located on the campus of UMBC in Baltimore, MD USA within a suburban neighborhood landscape roughly 5 miles from Baltimore City. The two 6.25 ha sites (250 m x 250 m) are located near the intersection of the Piedmont and Coastal Plain physiographic provinces of the eastern United States. Forest and tree-cover area occupies roughly half of each site, with the remaining area occupied by non-forest land cover types associated with UMBC (e.g., maintained grass, pavement, roads, parking lots, and buildings). Both sites are temperate deciduous forests of similar species composition and representative of United States east-coast forests (tulip poplar association).
The forest overstories are dominated by oak (Quercus spp.), beech (Fagus grandifoliaa), tulip poplar (Liriodendron tulipifera), hickory (Carya spp.), and black gum (Nyssa sylvatica) species. The forest understories are dominated by black cherry (Prunus serotina), black locust (Robinia pseudoacacia), and red maple (Acer rubrum). The second-growth forests are primarily remnant woodlot patches from previous agricultural land use. Based on aerial photo interpretation, the forests are greater than 75 years old but have several areas of new regrowth following disturbances caused by UMBC campus construction. Recently distubed areas are dominated primarily by relatively younger (< 35 years old) black locust, black cherry, and ash species (Fraxinus spp.).
Permanent sites and the first tree census were established in 2012 within a surveyed 25 m x 25 m quadrat grid roughly centered on two main woodlot patches that are 650 meters apart (named 'Knoll' and 'Herbert Run'). Within forested / woodlot quadrat areas, all tree stems (living or dead) greater than or equal to 1 cm in diameter at breast height (DBH) that reached a height of at least 1.37 m above the ground were tagged, mapped to the location within the quadrat, measured, and identified to species between 2012-2014. Outside woodlot areas, all tree stems within the plot areas were mapped by digital aerial photo-interpretation or precision GPS (global positioning system) equipment and were similarly tagged, measured, and identified. In total 7,161 unique tree stems were inventoried. Across the total site area (12.5 hectares), basal area was 12.9 m2 ha-1 with a density of 597 stems per hectare. Within forest / woodlot areas only (roughly 6.25 ha across both plots) basal area was 25.6 m2 ha-1 and density was 1,140 stems per hectare. These stem densities are similar to those seen in other eastern US temperate deciduous permanent forest sites. A total of 68 unique species were identified across both sites, which includes both native, introduced, and planted / ornamental taxa. Approximately 11% of all stems were identified as standing dead trees, representing about 12% of the within-woodlot total basal area.