City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: https://read.dmtmag.com/i/30662
be selected for the site. The soils and infiltration need to be correct for the intended volume of stormwater. We have opportunities to advise city planners on soil recommendations and species choices for suitable sites. The final step in any design is to include a long- term maintenance plan so the trees are maintained and grow the large canopy we envision when the plan is drawn up. —Gordon Mann, Consulting Arborist and Urban Forester, Mann Made Resources, Auburn, California Plants that tolerate both wet and dry soils: Trees American Hornbeam (Carpinus caroliniana) Baldcypress (Taxodium distichum) Bur Oak (Quercus macrocarpa) Honeylocust (Gleditsia triacanthos) Pin Oak (Quercus palustris) Planetree (Platanus x acerifolia or P. occidentalis) River Birch (Betula nigra) Swamp White Oak (Quercus bicolor) River birch (Betula nigra) is a good candidate for many rain gar- den and bio-swale applications. Pervious concrete was used for the parking spaces in this Upper Arlington, Ohio park. Photo by Steve Cothrel Bioswales and raingardens are sites where stormwater can be retained and allowed to recharge slowly in the ground, infiltrating back into the soil. This reduces stormwater overloads to existing infrastructure systems, which otherwise cause flooding. Advantages also include water table recharge, a reduced need to build expensive storm sewer infrastructure, and a smaller volume of polluted water running into our lakes and streams. A bioswale or raingarden is an area that is graded to col- lect surface rainfall and runoff from paved surfaces. It should be constructed to allow for good infiltration, but it may have standing water for part of the time. In fact, the recognition that these landscapes may be flooded for some of the time has largely driven the choice of plant materials. However, raingardens and bioswales are not always wet. The key to successful plant selec- tion for these sites is to choose plants that can tolerate wet and dry periods. Trees and shrubs that can accomplish this in the Northeast, Mid-Atlantic, and Midwest regions of the U.S. follow. It is important to keep in mind other selection criteria such as soil pH, hardiness, pest and disease resistance, and sun and shade exposure when making these selections. www.urban-forestry.com Red maples (Acer rubrum) and grasses fill rain garden structures that allow stormwater to enter both through openings in the street curb and scuppers in the stone edge along the sidewalk. Photo by Steve Cothrel 31 Shrubs False Indigo Bush (Amorpha fruticosa) Black Chokecherry (Aronia melanocarpa) Buttonbush (Cephalanthus occidentalis) Grey Dogwood (Cornus racemosa) Silky Dogwood (Cornus amomum) Redtwig Dogwood (Cornus sericea or Cornus alba) Winterberry Holly (Ilex verticillata) Bayberry (Myrica pensylvanica) (for more upland edge spots) Dwarf Purple Osier Willow (Salix purpurea ‘Nana’) —Dr. Nina Bassuk, Director, Urban Horticulture Institute, Cornell University