Caring for Trees at Zoos:
Enhancing Aesthetics and Preserving a Healthy Ecosystem

When guests visit zoos, they do not always notice the trees immediately, but when they seek out shelter from the heat or when they enjoy the realistic design of an exhibit, they start to see the important role trees play.
As Parks Director for the Cape May County Zoo and Park, in Cape May Court House, N.J., Mike Laffey is making trees a priority in the zoo, park and in a newly designed area called the Born Learning Trail, a third of a mile asphalt and mulch trail designed to promote physical activity for children.
“This is a project being completed by the county health department and United Way. The idea is to get children to be as active as possible,” Laffey noted. “Along the trail, there are stations, and each one has instructions for a specific activity such as ‘play hopscotch.’ The trail also will have different trees, which will be tagged so that children and adults can learn to identify them.”
Owned by Cape May County, the zoo and surrounding park has free admission and welcomes between 385,000 and 420,000 guests annually, most of whom visit between May and September, the peak months for the shore community. Home to more than 550 animals, the zoo displays a variety of native and non-native trees including Oak, Pine, Holly, Japanese Maple and Bamboo.
“Trees are a very important part of zoo life,” Laffey said. “We are very conscious of delivering the message that we need to conserve and sustain them. We are aggressive in caring for trees from fertilizing to identifying those that are in hazardous situations due to damage or disease. We have tree experts on staff who prune trees, and if need be, take them down. We recycle trees most of the time, and if we can’t we will send it off to the Municipal Utilities Authority, who will turn the tree to mulch and use it elsewhere.”
Along with providing an authentic atmosphere for exhibits, the Bamboo trees are used for food for some zoo animals, and are also cut into sections and made into toys for the monkeys.
Horticulturists at The Calgary Zoo and Botanical Gardens in Calgary, Alberta, Canada, consider the entire zoo one garden. The 80-acre zoo maintains a six-acre area within its borders that is dedicated just to horticulture. The Dorothy Harvie Gardens is a show garden of hardy plants and showy annuals and also encompasses the ENMAX Conservatory, home of the zoo’s indoor botanical collections.
“We try to have a wide variety of trees at the zoo. Evergreens are trees that are native to this area, and we have many of them here including Scotch Pines and Siberian Cedars,” said Boyd Nave, interior gardener for the zoo. “We try to tailor trees to our outdoor exhibits, which is a challenge sometimes. Our exhibits represent so many regions of the world including Eurasia, South America, Australia, Africa, and of course, the Canadian Wilds. It takes a great deal of research to find the right trees and plants that simulate those which would exist in the natural environment but would not survive in our climate.”
The zoo maintains a number of indoor exhibits including the African Savannah Building and the TransAlta Rainforest, which immerse guests into the sights, sounds and climate of these exotic locations.
“In the interior exhibits, we can get the actual trees and plants that one would see in these regions because we can control the climate and environment,” Nave explained. “For instance, we do have African Mahogany and African Oil Palms. We do not label these trees as much as we do in the exterior part of the zoo because we do not want to take away from the natural experience of the exhibit.”
Nave noted that daily maintenance and care is needed for all trees, especially those in the interior exhibits.
“Care for the trees is ongoing. For example, in their natural setting, Mahogany trees can grow to 200 feet. They can’t grow that large here, so we need to keep them at a certain level, which takes a specialized skill to do so. Our goal is to conserve and show the beauty of these trees, which many are endangered because the wood is so in demand.”
The trees in the exterior exhibits do not require quite as much maintenance, and they are labeled for guests. Automatic sprinklers water them regularly and the staff monitors the soil.
As project designer for the 580-acre Columbus Zoo and Aquarium in Columbus, Ohio, Karen Schenk oversees about 120 developed acres. More than two million guests visit the zoo each year to enjoy exhibits such as the African Rainforest, which contains more than 700 species of trees and plants, Asia Quest and Australia and North America, which is home to its newest exhibit Polar Frontier.
“We have many varieties of zone-tolerant trees from Sweet Gum to Honey Locust to Maples and Sycamores. We used to have more Ash, but that species is struggling now – a victim of an insect that feeds on them and that has spread throughout many areas of the country.”
Deciduous trees are used throughout the zoo for shade and decoration, while Evergreens such as Spruce and Pine are used as natural screening in exhibits.
“We mimic plants and trees for our exhibits. Our climate would not support many species that would exist in the natural habitats of Africa and Asia, so we research and find trees and plants that might look like those in the natural environments but can survive here,” Schenk said. “For example in our African Rainforest, we have plants with large waxy leaves and vibrant colors that will thrive in our climate and they look like plants that would be in real rainforest. Our goal is to immerse our guests into the rainforest experience, so every detail of the exhibit has to contribute to that goal.”
While developing authentic horticulture designs for exhibits is difficult, the most challenging aspect is plant toxicity.
“When we do our research to see what plants and trees look similar to those in the real environment, we have to go the extra step to determine if the species we are using are going to be highly toxic,” explained Schenk. “We are not only worried about people, but the animals. We have to consider so many circumstances, such as people breaking off twigs and trying to lure an animal over to them using that twig. If that twig is toxic to an animal, that is a problem. We build a matrix of the various toxicity levels and what they mean to specific animals.”
As for maintenance of the trees and plants, Schenk noted that the staple trees that are common to the central Ohio area are easier to care for than exotic trees.
“We don’t have to tend to our staple trees on a daily basis,” she said. “we have irrigation systems and we keep track of them in specific ways during their growth. For instance, during the first one to three years of a tree’s life, we want to ensure that it is healthy and growing, so we are more vigilant, but from three years on, it’s more maintenance and making sure the tree stays healthy.”
The 17-acre Abilene Zoo in Texas is home to more than 600 animals from around the world. The zoo also displays a variety Oak and Milkweed and other trees that are native to the Abilene area.
“We include trees and plants in our exhibits,” said Bill Gersonde, zoo director. “It is very expensive to have the trees from distant regions here, but we now have a horticulturist on staff who can research and find trees and plants for exhibits that resemble the real thing.”
Abilene Zoo is growing. An additional 26 acres might be developed in the near future.
“It is important that our visitors pay attention to all their surroundings in the zoo – not just the animals,” Gersonde explained. “If we are to be true conservationists, we have to understand how plants and trees affect and aid in the survival of animals. It is our plan to label the trees next year so that guests can read about them as they explore the zoo.”
As Senior Horticulturist for the Akron Zoo in Akron, Ohio, Brad Haben oversees 52 working acres. The Akron Zoo hosts more than 315,000 guests each year and is home to 700 animals including endangered Humboldt penguins, Sumatran tigers, sloth bears and snow leopards.
“When it comes to the trees and plants, our goal is to create a complete immersion experience,” said Haben. “We find mimic plants for our exhibits when we cannot support actual trees and plants from those regions in our environment. We understand that trees and plants are extremely important in making an exhibit successful, so we put a lot of work into finding species that will fit.”
On the zoo grounds, trees that are native to the Akron area provide shade and atmosphere. The zoo has older Chestnut trees as well as White, Red and Pin Oak trees.
“We use an arbor service to trim and maintain the trees,” Haben said. “We take the health of the trees very seriously. They are beautiful. We live in an industrialized society with pollution, so these oaks now live to 120 years and we consider that old. Without pollution, they would be living to 600 years.”
Haben said the zoo is vigilant with the pruning and care of the trees because they are so large and could harm people or property if they fell. They are trimmed, fertilized and examined regularly and are not treated with chemical pesticides. Haben and his staff’s efforts paid off when during the zoo’s accreditation process last year, the trees and landscaping were recognized.
“The trees add a great deal to the experience of our guests at the zoo,” Haben noted. “We have beautiful picnic grounds surrounded by magnificent trees, and we label each tree so that our guests can learn about them.” –

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