The Health of Trees in Bioretention: A Survey and Analysis of Influential Variables

This research study compared the health of trees in bioretention systems in TN and NC with trees in other open-grown, urban settings.

Results from this comparison showed that trees from five of the six species examined in the study [red maple (Acer rubrum), river birch (Betula nigra), pin oak (Quercus palustris), eastern redbud (Cercis canadensis), and lacebark elm (Ulmus parvifolia)] were less healthy, having smaller composite crown volume (CCV) and composite crown surface area (CCSA) values than similar non bioretention trees. Only bald cypress (Taxodium distichum) exhibited better health in bioretention.

These results suggest that natural growing habitats and species-specific preferences for site condition should be considered when selecting a tree species for a bioretention practice. Drought tolerant trees that thrive in sandy, well-drained, nutrient-deficient soils with periods of water inundation will tend to be healthier in these types of stormwater practices.