All bark but no bite, trees are arguably one of the most important natural resources on the planet. Forests are the lungs of the world, taking in carbon dioxide and releasing oxygen during photosynthesis. Trees provide vital food and habitat for countless species of planets and animals. From construction materials to the paper this article is printed on, tree products are an integral part of human society. Needless to say, our lives are deeply connected to trees. What a better way to thank the trees for what they do then to plant a tree? And what a better day to plant a tree then on Arbor Day?
Officially first proclaimed in 1874 in Nebraska, Arbor Day is now celebrated in all 50 states and around the world. In Colorado, Arbor Day is celebrated on the third Friday in April. The day is set aside to celebrate trees and encourage tree planting. Before you get swept up in the spirit of the day and plant that future shade tree in your yard, you should know that not all trees are created equally. Not all trees belong here in the mountains. The concern is not a palm tree freezing to death in your yard, the concern is that certain species from outside our region can thrive and take over with negative consequences for native flora and fauna. These plants are known as invasive species.
When it comes to invasive tree species to avoid planting this Arbor Day, make sure the Russian olive and the tamarisk (also known as the salt cedar) are on the do not plant list. Both of these small trees are originally native to Europe and Asia. Planted in the United States for windbreaks and stream bank stabilization, the populations of these nonnative trees have greatly expanded with increasingly negative impacts on native ecosystems. The tamarisk raises the salinity of the soil surface to the point that the soil is inhospitable for native plants. Additionally, the tamarisk is an extremely water hungry plant and has been shown to contribute to the intensity of drought. Russian olive also outcompetes native plant species thanks to its ability to grow in a variety of soil and light conditions. Similar to the tamarisk, Russian olive also can deplete water resources.
As a result of these negative impacts and their aggressive ability to spread, these two tree species have been listed as “List B” species on the Colorado Noxious Weed Act. Depending on the infestation, these plants must be eradicated, contained or suppressed. The best way to reduce the impact of these invasive tree species is to prevent future populations from being established and that is why it is important to understand what you are planting on Arbor Day or any day. Instead, consider planting native trees this Arbor Day. Native trees support a wider variety of local wildlife by providing food and shelter than nonnative trees support. They also require less water, fertilizers, and pesticides than nonnative trees. Talk to your favorite nursery about which plants are native and which are the most suitable for your yard. Whether it be a celebratory tree planting or a hike through a shady forest, take a moment this Arbor Day to reflect on the many ways trees have positively impacted your life.
Scott Dunn is the Community Programs Coordinator at Walking Mountains Science Center and will be celebrating Arbor Day relaxing in his hammock between two trees.
Arbor Day Info: https://www.arborday.org/celebrate/?Trackingid=404
Saltcedar Fact Sheet: https://drive.google.com/file/d/1qMxP9ogp7Z_Q_bnCSlF6wyKdkIELKOCO/view
Russian Olive Fact Sheet: https://drive.google.com/file/d/18pDzVp6Gwl42CQmQZdyQh4PvMqkatahk/view