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Trees That Thrive in the Urban Jungleby Contributor April 13, 2016
City life places a number of unique demands on the trees living in them. In addition to satisfying their needs for sunlight, water and appropriate soil chemistry, city trees must cope with polluted air, constricted growing spaces and little to no regular maintenance.
It’s a tall task. One that lies outside the capabilities of many species.
Plant a few Lombardy poplars (Populus nigra ‘Italica’) on a cramped city lot and you’ll regret it. Between their invasive root system and habit of shedding branches, you will be faced with a variety of logistical nightmares. This, of course, assumes that the tree survives the sulfur-laden air common to many urban areas.
You also have to consider any potential litter problems created by some trees. You do not want to plant a sweetgum tree (Liquidambar styraciflua) over a commonly trodden sidewalk unless you select one of the fruit-free cultivars. Even trees with edible fruit – which often work very well in suburban and rural areas – can be problematic in dense urban areas.
Instead, you must select a species that can thrive in the urban habitat. One with the right combination of traits and tendencies.
A few traits are so at odds with city life that they
categorically disqualify trees displaying them. Very large trees – particularly
those with widely spreading crowns – are almost never suitable for the cramped
confines of most cities. Sure, you’ll see a few scattered coastal redwoods (Sequoia sempervirens) or white pines (Pinus strobus) living in cities, but
those that thrive in them are the exception to the rule.
Similarly, species that commonly exhibit poor growth habit, low wind resistance or weak wood are too dangerous to plant in high-traffic areas. Accordingly, Callery pears (Pyrus calleryana) and cottonwoods (Populus tremuloides) are bad choices.
Shallow, invasive roots systems are also problematic for the sidewalks, sewer lines and foundations in the vicinity of a street or lawn tree. This rules out most willows (Salix spp.) and many maples (Acer spp.). Trees that require frequent, regular maintenance are also poor choices for urban locations, as are trees that need copious water or are unable to tolerate air pollution, high temperatures and compacted soil.
This means that a generic, idealized city tree should:
·Be relatively small – particularly as it relates to spread
·Possess a relatively tame root system
·Able to tolerate polluted air
·Require little maintenance
·Be relatively litter free
Of course, aesthetics are also important, but they should only be considered after the above factors are taken into account.
Recommended Species for Urban Locations
While there are few clear-cut rules regarding trees (or any other living organisms, for that matter), some trees tend to thrive well in urban settings, and should be on your short list for consideration.
·London plane trees (Platanus × acerifolia)
·Maidenhair trees (Ginkgo biloba)
·Crepe myrtles (Lagerstroemia spp.)
·Arborvitaes (Thuja occidentalis)
·Red oaks (Quercus rubra)
·Valley oaks (Quercus lobata)
·White firs (Abies concolor)
·Japanese maples (Acer palmatum)
·Trident maple (Acer buergerianum)
·Downy serviceberry (Amelanchier arborea)
·Redbud trees (Cercis spp.)
·Washington Hawthorne (Crataegus phaenopyrum)
Of course, not all of these species will work in all urban areas – you must take soil conditions, sun exposure and soil compaction levels into consideration before making definitive choices. Regardless of which species you select, your trees will fare better with the help of a competent, reliable tree service. So, if you need professional tree care in Larkspur, San Francisco or Millbrae, give us a call and let us help keep your trees healthy, happy and looking their best.
Photo from MorgueFile