When it comes to plant variety in a planned arboretum like Shelby Avenue, it’s important to consider how different species of trees, plants, and animals will benefit one another. Shelby Ave. hosts a variety of trees that are native to Tennessee, but there are many non-native trees here as well. Read on for some insight on how we chose to plant specific trees in Nashville’s newest arboretum.
Urban landscaping has always placed a high emphasis on non-native plants when planning a city’s greenery. In the past, the reasons for this were largely aesthetic. Did you know that the vast majority of the iconic palm trees of Hollywood and Los Angeles are not native to California? They were brought in by city planners in order to create an image for their city. There’s no doubt that this worked for L.A, but these non-native trees provide nothing for the residents of Los Angeles, and that’s a problem. As the palm trees reach old age and begin to die out, there are no plans to plant new palms in their place. City planners now understand that every aspect of a city’s infrastructure, including its greenery, needs to serve a purpose.
Fortunately, many native Tennessee trees are perfectly suited for the Shelby Avenue Arboretum and provide countless benefits to the residents beyond their natural beauty. California and Florida’s palm trees are a good example of why non-native trees need to be selected carefully for an arboretum, but that doesn’t mean they shouldn’t be used at all. Non-native trees in an arboretum are useful educational tools and can be exotic without feeling too out of place. As an arboretum, it’s our goal to expose people to trees they’d otherwise not encounter. Additionally, just because a tree is non-native does not mean it isn’t good for the native trees around it. Many trees attract beneficial insects and animals, and provide things like shade and fruit for pedestrians. In an ecosystem, many factors can come together to reach a balance, and that’s been one of the thrilling challenges in planning Shelby Avenue Arboretum.
It’s not a matter of only using native trees in an arboretum. Rather, selecting and planting an exciting variety of different trees is greatly important for an arboretum’s mission. As we go into some of the arboretum’s native and non-native trees, it’s important to keep in mind that these trees were all hand-selected to put up with the particular climate of Nashville, and the unique challenges of urban life.
There are actually unique benefits to using non-native trees in an urban setting, but that practicality depends on several factors. Many trees native to Tennessee are meant to grow in the shade surrounding larger trees. In a natural forest, there is a mix of high canopy and low canopy trees. Some trees grow best in the shade of other trees, while others need to be the tallest in the forest. When you’re planting along a roadside, trees that need some shade are not going to be the best fit. Trees along a street need to provide shade, but also can’t grow tall enough to dwarf the other trees around them. So when you look at an arboretum and don’t see massive trees and small trees alongside each other, know that the reason for this relative uniformity in size is not all aesthetics.
In a city like Nashville where many native trees are better equipped to grow in the shade of larger trees, non-native trees can fill in the gaps. Non-native trees are often selected based on a similar degree of hardiness to drought and agreeable soil needs. Many non-native trees could be grown in Nashville, but the fertilization and water needs vary so greatly that it wouldn’t be wise to use them. When the trees of an arboretum all need similar soil, water, and sunlight, they can flourish together and be far more sustainable than ornamental and needy non-native trees. In an arboretum, things often come down to practicality.
Why is it important to have native trees? Trees provide a home and food source to many insects and animals, who in turn benefit the ecosystem by spreading pollen, fertilizing plants, or killing harmful insect populations. Nature has spent thousands of years developing an equilibrium, and there can be dozens of ecosystems in the same square mile.
Many species of maples, oaks, yellow poplars, and dogwood trees are all very common in Tennessee’s natural woodlands. These species of trees have found their way into our arboretum, introducing the city to trees that often can only be found in rural areas outside of Nashville. On Shelby Avenue, you can expect to see familiar trees alongside trees native to other parts of Tennessee and the surrounding states. These trees are all considered native within our arboretum because they could grow here without human intervention. It’s incredibly important to conservation and sustainability that we focus on what we have near us for a variety of reasons. By preserving trees in urban settings, we ensure that they continue to grow, develop, and evolve.
Why are native trees better for the environment? It’s much more efficient to plant trees that are native to your area because they’re already adapted to the soil, climate, and rainfall (or lack thereof). Local trees are also the best at preventing erosion and deterioration of the soil, and by extension, roadways and sidewalks. Trees can also soak up a lot of rainfall in a city, helping to make sure that flooding is kept to a minimum. There’s a lot that native trees can do for us, and that we can do for them.
One highlight of the native trees shines in the variety of magnolias that are planted in Shelby Avenue Arboretum. With four magnolia species, you can expect to experience the southern charm and fragrant flowers that magnolias are famous for. Magnolia flowers are a unique sight in the spring, and not every area of the country is fortunate enough to see magnolias in bloom. Another important native species in the arboretum is the pecan tree. Pecans are a huge part of Tennessee history, growing mostly in the western part of the state. Thanksgiving wouldn’t be complete without pecan pie, but did you know that some pecan trees can live more than 300 years? These hardy Tennessee native trees offer a lot more than just their nuts.
While non-native trees may have some stigmas to shake off, their importance in an arboretum like Shelby Ave. cannot be overstated. When carefully selected and considered in a larger scope as part of a complete ecosystem, non-native trees can do a lot more than just look unique. Some non-native trees in Shelby Avenue Arboretum aren’t even from the same continent! Take the Japanese maple as an example. This cultivar, known as the Emperor I Japanese maple, is not from around here, but it works incredibly well in our climate regardless. These trees only grow to a height of 10 – 15 feet and don’t flower in the spring but make up for it almost year-round with their stunning, deep red color that is sure to catch the eye.
Some of the cherry trees being planted, especially along the red and blue sections of the arboretum, are also not native to Tennessee. The Okame cherry tree, for example, is a cultivar of the cherry tree that was created by hybridizing the Taiwan flowering cherry and Fuji cherry trees in England. So these are two trees native to parts of Asia, cultivated in England some 200 years ago, now being planted in Nashville. It doesn’t get much less native than that, yet these cold weather-tolerant trees are a perfect fit for this city. Trees that blossom like these cherry trees support local pollinators like bees, who are themselves not native to the U.S. Having as many blooming trees as possible at the arboretum necessitated the inclusion of many non-native trees that can put up with city living.
When planning an urban arboretum, you need to find trees that work well alongside city streets, considering power lines and surrounding trees that also need sunlight. Non-native trees are selected for their ability to grow in shade, or simply to grow much shorter than other trees. The cherry trees mentioned above also produce beautiful blossoms in the spring, and what these small trees lack in size they make up for in natural beauty and aromas. All of the trees in Shelby Ave. Arboretum were carefully selected to cooperate and thrive alongside one another. Much like the city of Nashville, these trees have diverse backgrounds, rich histories, and tons of stories to tell.
On the other hand, many of the non-native trees were selected due to pure practicality. A lot of native species cannot tolerate all of the salt, oil, limited space, and other factors that city streets pose. The non-native species planted at Shelby Ave Arboretum were picked because they were readily available, as many native trees are harder to source. Logistically, it’s easier to source non-native trees because they’re what’s on the market. An arboretum is nothing special without variety, and the selection of hardy non-native trees made it much easier to incorporate a broad range of species to be put on display.
But non-native trees aren’t without their setbacks. One risk posed by non-native trees is that they can become invasive if not properly monitored. Not all non-native trees run this risk, but there are some non-native trees that spread too quickly. Care was taken to avoid these types of trees, like the rampantly spreading tree of heaven for example. Any trees that pose a risk for spreading and negatively impacting Tennessee trees, or the infrastructure of the city, are not included in the arboretum. If something changes, we will be sure to remove high risk trees and replace them with native plants.
Shelby Avenue Arboretum uses trees from Nashville and surrounding states, as well as trees from across the ocean to provide natural beauty to a city that could always use more. An arboretum is a lot like a living museum, and being able to display trees both strange and familiar is a unique privilege for arboretums. If you’d like to learn more about the Shelby Avenue Arboretum, shop our selection of trees, and support our ongoing fundraising and planting projects, don’t hesitate to reach out. We’d be happy to talk trees with you.
The Shelby Avenue Arboretum is a community-grown project led by Nashville Tree Conservation Corps and is in partnership with NTCC and Metro Nashville.
Nashville Tree Conservation Corps
PO BOX 60683
Nashville, TN 37206
