Measurement and Prediction of Tree Growth Reduction in Parking Lots Based on Apparent Available Soil

Summary

Urban conditions have been thought to affect tree growth, but there is little conclusive evidence as to the severity of this influences or whether different species respond deferentially to urban stress.  It is important to understand reduced growth expectations, because they affect our design choices for the urban tree canopy, particularly as required by legislative mandate.  Five tree species (Acer rubrum, Prunus serrulata, Pyrus calleryana, Quercus palustris and Zelkova serrata), growing in parking lots ranging from 18-23 years old in central and northern New Jersey were measured.  Tree height, diameter at breast height (DBH), and canopy radius were measured, as was apparent plant available soul (nonpaved planting zone area).  Tree DBH, commonly recorded for many municipal inventories, was found to be a useful predictor of canopy area.  Data were normalized within site, to facilitation multiple site analysis.  Across different parking lots, reductions in tree size were consistently associated with reduced apparent soil access.  A previous study from Florida was used for comparison of regional data, permitting conclusions on canopy reductions, relative to specification of design space for tree establishment.