Design Choices and Urban Forest Characteristics in Raleigh, North Carolina, U.S. Parking Lots    (View PDF)

Evan M. Keto, Melissa R. McHale, George R. Hess, Bronson P. Bullock, and Gary B. Blank

Abstract: Trees provide important environmental, economic, and social benefits that can help to offset the negative effects of parking lots. Many cities recognize that adding space for trees in parking lots is beneficial and have created regulations that dictate minimum requirements for tree planting. However, it is not clear if tree plantings in parking lots achieve the urban tree canopy goals initially imagined by these communities. The study authors sampled parking lot trees in Raleigh, North Carolina, U.S., to determine how species composition and urban forest structure vary with respect to parking lot size, shape, and design. Using a two-stage cluster sampling scheme, Raleigh’s parking lots were found to contain 44,000 ± 24,000 trees (95% confidence interval). No differences in tree compos tion were explained by the size or shape of the parking lots. Planting spaces within the parking lot that were preserved during construction were found to have more trees, canopy, and basal area per hectare than designed planting spaces in which the number, spacing, and species of trees were prescribed. Among designed planting spaces, large, linear rows had greater canopy and basal area per tree but fewer trees per hectare than smaller, circular islands. These results suggest that decisions made during the design process may have lasting effects on the structure and function of this portion of the urban forest.

Keywords: Automobile; Car Park; Environmental Impacts; Parking Lot Design; Transportation; Tree Planting; Tree Preservation; Urban Forest Structure.

https://doi.org/10.48044/jauf.2012.009