Plant diversity is not just for the wide open prairie or local forest preserve. Bringing a variety of tree species to streetscapes, parking lot and residential landscapes creates a diverse urban forest fabric. This provides a more resilient ecosystem that can withstand pressures when plant disease, insect pests or extreme weather comes to town. Chestnut Blight, Dutch Elm Disease and now Emerald Ash Borer have proved that monoculture plantings can be expensive and dangerous when they fail.
To diversify the landscape plantings in your part of the city, a good rule of thumb is the 30/20/10 rule: In any community, no more than 30 percent of trees should be within the same family, no more than 20 percent should be from the same genus, and no more than 10 percent should be the same species. Two examples trees are Red Maple and White Oak.
Common Name: Family Genus Species
Red Maple: Aceraceae Acer rubrum
White Oak: Fagaceae Quercus alba
Applying this rule at the micro level is a way each of us can contribute to ecosystem diversity. This can be difficult when working in the urban environment given the many constraints faced by street trees. Where there is room for tree roots to spread out in fertile soil and for branches to avoid overhead wires the list of possible tree types gets much bigger than what is often possible in city parkways.
Not sure which trees to choose? Upland Design has had success with these varieties:
Autumn Gold Ginkgo, Black Hills Spruce, Espresso Kentucky Coffeetree, Exclamation! London Planetree, Redmond Linden, Accolade Elm, Skyline Honeylocust, Marmo Maple, Speckled Alder, Little King River Birch, Bald Cypress, China Snow Peeking Lilac, Black Tupelo, English Oak, and Chicagoland Hackberry.
The Morton Arboretum Tree and Plant Finder can also be a great resource.