AFRICAN
RIFT VALLEY GARDEN TOUR
Many visitors can remember a time when
they entered the zoo and stared up the long steep hill that lead to our
world famous giraffe herd. A line of Silver Maples was the only vegetation
to provide shade and a relief from the hot summer sun. Now that line of
trees is gone and in its place stands a mixed planting of grasses and shrubs.
The
landscape in the African Rift Valley was designed to replicate the thornbrush
savanna of Africa. Being at 7,000 feet in elevation, we could not use Acacia
trees and others plants typically found in that region.
After the successful My Big Backyard
project undertaken by the horticulture staff in summer and fall of 2001,
we decided to complete this much larger project in-house rather than utilizing
a contractor. Many large 3-4" caliper specimens were planted with the hope
that they would better withstand frequent animal contact. By combining
swathes of grass and thorny trees and shrubs we intend to create a landscape
similar to a thornbrush savanna. We opted not to used Honeylocust, even
through they resemble the Acacia trees growing in Africa, because large
specimen do not transplant well on our site.
Looking across a thornbrush savanna you should see a canopy of thorny
trees, a mid story of shrubs, and a mix of grasses and flowering plants
covering the ground. Savanna plants are adapted to low levels of rainfall
and do not look lush or tropical so we needed to select plants with smaller
leaves. The Cheyenne Mt. Zoo selected small trees and large multi-stem
shrubs like Silver Buffaloberry, New Mexico Privet, Honeysuckle, and many
species of Hawthorn because they accomplished these objectives. The
selection of grass species provided a variety of textures in the height
range from 2 to 10 feet tall.
Another important thought in plant selection process was “will this
be functional?” Plants with similar water needs were grouped together according
to irrigation zones. All plants to be place in or near the exhibit were
checked for toxicity. Larger trees were 
placed
in a few key locations to provide shade along parts of the path. Native
plants were selected for non-exhibit hillside revegetation. Because of
the potential for animal damage, most of the plants inside the exhibit
were selected because they have the ability to re-sprout from the root
system, grow quickly, and have been previously tested on grounds for hardiness.
Large planting areas were designed to limit natural browsing and minimize
use of hotwire.
Cheyenne Mountain Zoo purchased several decorative planters to place
along the elevated boardwalk. Often potted plants will struggle to survive
through the winter because they are subjected to Colorado's extreme and
irregular winter temperatures. Plants in the ground benefit from the insulation
of the surrounding soil. snowmound spirea, red yucca, fernbush and various
shrub roses seem to have survived their first winter.
PLANT LIST:
Trees:
Crataegus ambigua, Russian Hawthorn
Crataegus crusgalli, Cockspur Hawthorn
Crataegus douglasii, Douglas Hawthorn
Crataegus mollis, Downy Hawthorn
Forestiera neomexicana, New Mexican Privet
Gymnocladus dioicus, Kentucky Coffeetree
Prunus americanan var. manchurica, Manchurian Apricot
Salix ‘Prairie Cascade’
Shrubs:Amorpha fruticosa, Indigo Bush
Caragana arborescens, Siberian Peashrub
Cotoneaster lucidus, Peking Cotoneaster
Fallugia paradoxa, Apache Plume
Lonicera spp. Honeysuckle
Potentilla fruticosa ‘McKay’s White’ McKay’s White
Potentilla
Ribes inerme, White-stem Gooseberry
Rosa woodsii, Woods Rose
Sheperdia argentea, Silver Buffaloberry
Grasses:
Andropogon gerardii, Big Bluestem
Andropogon sacharoides, Silver Bluestem
Calamagrostis x acutiflora ‘Karl Foerster’ Feather
Reed Grass
Elmymus glaucus, Lymegrass
Erianthus ravennae, Plumegrass
Miscanthus sinensis ‘Autumn Light’
Miscanthus sinensis ‘Gracilimus’
Panicum virgatum ‘Rahbraun’
Panicum virgatum ‘Prairie Sky’
Schizachyrium scoparium, Little Bluestem
Spartina pectinata, Prairie Cordgrass
Stipa tenuissima, Ponytails
Sporabolis wrightii, Sporabolis
Perennials:
Kniphofia spp., Torch Lily or Red-hot poker
Sidalcea ‘Partygirl’, Partygirl False Mallow
