April is National Landscape Architecture Month, reminding us to appreciate the national capital’s unique urban landscape. Springtime weather, lengthening days and the explosion of colorful blossoms draw us outdoors. But Washington’s aesthetically wonderful landscape and abundant vegetation also enhance the city’s ecology and conserve energy.
Unlike other cities with long, cold winters or long, hot summers bracketed by relatively brief spring and fall periods, Washington is blessed with four distinct seasons, each of comparable duration. Thus Washingtonians can comfortably spend substantial amounts of time outside much of the year.
With the retreat of winter, debris is being swept off terraces, decks and balconies. Homeowners, along with landscape contractors and nurserymen, are beginning to attend to lawns and gardens — pruning, spreading mulch, planting annuals, fertilizing trees and shrubs. Brown grass is again turning green.
The arrival of pleasant weather motivates some to walk a half-mile or even a mile rather than driving or riding transit. In early spring the population density of the public realm soars. People flock to the growing number of cafes and restaurants offering outdoor seating, animating downtown and edge-city streetscapes as they dine.
A remarkable variety of wildlife share our appreciation for Washington’s urban landscape. The city’s deciduous and evergreen trees, ornamental shrubs and broad lawns are habitats for many species of birds, including finches, cardinals, morning doves, tufted titmice, hummingbirds, woodpeckers and, of course, messy Canada geese. Predators such as red-tail hawks, turkey vultures and peregrine falcons regularly cruise overhead.
Moreso than many cities, metropolitan Washington is home to an assortment of freely roaming mammals. Residential yards and gardens constitute a veritable salad bar for the steadily rising population of urbanized, white-tail deer who have little fear of humans and pay little heed to moving vehicles and backyard fences. When I was growing up in Texas, where deer hunting was a major pastime, one was lucky to get within 200 yards of a deer. At my house in the District, deer regularly hang out just a few feet away from our back door, grazing on the lawn as if they owned it.
Foxes and coyotes prowl the Washington area, along with raccoons and possums. Gray squirrels are everywhere, and in recent years chipmunks have invaded. But you won’t see dead squirrels, chipmunks, raccoons, moles, mice or rats lying around outside except when flattened in the street. Scavengers quickly consume the carcasses, an indication that America’s capital city encompasses a relatively complete wildlife ecosystem.
Migration and proliferation of animals are facilitated by the extensive network of stream and river valleys weaving through the metropolitan region. In coming years, it would be little surprise if black bears, moving eastward from the Appalachian mountains in search of food, exploit these natural pathways and show up in the city more regularly.
Being well-vegetated yields significant environmental benefits, easily forgotten during winter months when deciduous trees are leafless, days are cold and the sun is low in the sky. But when the sun is high and daytime temperatures rise, leafy tree canopies provide indispensable shade that cools the ground, paved surfaces and building facades, in turn cooling the air around buildings. This reduces summer air-conditioning loads and energy usage, in addition to augmenting outdoor comfort.
Intensely vegetated urban areas significantly improve urban stormwater management by slowing and dispersing rainfall before it hits the ground. This allows soil to absorb, retain and filter rainwater more effectively. Trees, shrubs and ground-cover also prevent erosion and conserve topsoil. Through photosynthesis, vegetation helps purify the atmosphere by absorbing climate-changing carbon dioxide while emitting oxygen.
Washington’s plants and animals do produce some seasonal, unwanted side effects, most notably allergenic reactions to pollen and armies of warm-weather insects including ants, flies, mosquitoes, wasps, fleas, deer ticks, tent caterpillars and wood-boring carpenter bees. Fortunately, the benefits of living in a rich, urban environment, one in which humans, plants, animals and architecture coexist, enable most of us to tolerate and cope with these adverse effects.
Roger K. Lewis is a practicing architect and a professor emeritus of architecture at the University of Maryland.