The Value of Green

The beauty added to an urban environment by plantings needs no explanation. In addition to the soothing blend of colors and forms, vegetation reduces the energy and water demands of cities. Shade lowers heat absorption, reduces water loss and clears our pollution.Soil conservation and water quality continue to be important issues for protecting and improving the environment we all share. Drought tolerant plants such as Quercus macrocarpa or crabapples, continue to be important for windbreaks and can be utilized in dry climate landscapes to decrease water demand. Planting buffer zones along water-ways reduces soil erosion.

Natives like Viburnum dentatum or exotics such as Syringa meyeri ‘Palibin’ can withstand occasional flooding in these buffer areas. Yet, all these species add beauty with flower, fruit and foliage. Beauty may be in the eye of the beholder, but it is expressed in the landscapes vegetation. From roadsides to backyards, hidden hollow to sweeping views the vegetation can provide beauty in life. Summer and fall color of Acer palmatum ‘Atropurpurea’ or winter color of Salix branches brighten the scene. Feather foliage of Metasequioia glyptostoboides or the stiff sharp leaves of Yucca filamentosa add texture and color to the landscape.

While concrete and asphalt are necessary, paved areas increase heat retention in urban landscapes. “The center of the city absorbs 10% more solar than a corresponding green area, this is due to the concentration of construction, the asphalt pavement and the high heat conductivity of most materials used, such as reinforced cement.”¹ Research “estimates that urban heat could increase Tucson’s annual water demand by more than 5 percent by 2050.” ²

The solution is vegetation that provides dense shade in summer and little interference with solar heating in winter. Trees such as Acer platanoides or Tilia cordata provide dense shade and exhibit tolerance to urban pollution. The use of vegetation for street trees, parks or roof gardens will reduce heat retention in cities and thus energy demands for air conditioning, while still providing a more inviting landscape for the population. If the more pleasant surroundings reduce travel out of the cities that energy savings is a bonus.

The place of vegetation in the carbon cycle and the value of plants in reducing energy consumption is a part future. While the focus of the times may change (soil conservation after the dust bowl ears, beautification projects with Lady Bird Johnson, global warming and water conservation today) plants and the nursery and landscape industry are essential parts of the equation. From soothing the soul to reducing water and energy needs, the truly wonderful thing is that plants can help with all these issues at the same time

¹Elsa, Fabio Bertrand. “The urban heat isles and the micro-climatic variations brought about by vegetation” Bio Archectecture Copyright © 1998 - 2007 mybestlife.com
²Poole, B. “UA researchers studying links among paving, temperature, water use” Tucson Citizen Published: 10.31.2007

 

Halesia tetraptera (Carolina Silverbell)

Native from West Virginia to Texas, Halesia tetraptera (Carolina Silverbell) makes an outstanding addition in areas with acid soils. It can function
as a tree or a large shrub. As a tree, it grows to 40 feet tall with a 30 foot spread, making it a convenient shade tree for the smaller landscape. An
early bloomer, the white bell-shaped flowers appear just before or with the leaves in April and early May, adding a subtle beauty to the spring garden. The four-winged fruits appear ineptember, last into winter and make an interesting addition to fresh or dried floral arrangements.

From unique form and color to this hive of activity, Carolina Silverbell is a fantastic center piece for your customer's back yard. Its fissured bark colored brown, gray and black provides winter interest. The wood has many uses. It’s soft, close-grained used for veneers, cabinetwork, carving, turning and pulp.Squirrels cherish the seeds and the flowers are a favorite for bees. It’s very attractive when back dropped by conifers and underplanted with Azaleas and Rhododendrons.

Its cultural problems are few, as it is an exceptionally pest and disease free species, a plus for the home gardener or where pesticides are undesirable. It grows well in full sun or part shade, making this an excellent understory plant. The Silverbell needs acidic conditions (pH 5.0 to
6.0) however, and is subject to chlorosis in alkaline soils. It appreciates high humidity and regular moisture. It can be successfully cultivated in zones 5 to 9 and can succeed in the warmer areas of zone 4.In its native range, it’s often found growing in moist soils along watercourses in
the hardwood understory of the dense crown cover of these woods it must be able to grow in shaded conditions.

Silverbell is a long-lived species; healthy specimens can be expected to last a century or longer, making it a permanent addition to the home landscape. This is a precocious species and can flower when only 3 feet tall, a desirable trait for the impatient gardener.Great success has been reported with this tree in areas well outside it native range. It has been successfully planted in many areas of Europe as well, as the states of Washington, Oregon and California. It’s a beautiful, versatile small tree or shrub and deserving of wider use.