The Importance of Tree Biodiversity when PlantingWritten by Myles Cooley, Field Arborist II
With spring upon us, the planting season in Central Texas is coming to an end. Our team at Tree Mann Solutions want to share the importance of biodiversity when selecting trees for planting at your home or in a new development site.
A simple definition of biodiversity is the variety of life in a place or on Earth. The more biodiverse an ecosystem is, the healthier and more resilient it is to any environmental or biotic stressors. The same goes for the urban forest we all live in. Besides resiliency increasing with tree biodiversity, it also increases wildlife habitat and the many beneficial ecosystem services trees provide us.
Benefits of Biodiversity
To increase the likelihood that there will be a thriving urban forest for decades to come, we need to be mindful when selecting trees for planting. The most common mistake when selecting trees people will choose the same tree for a uniform look. This creates a monoculture that is then highly susceptible to diseases and pest. The famous Dutch elms disease wiped out a vast majority of the urban forest across the U.S. due to the prevalence of elm trees. Now the Emerald Ash Borer has wiped out many of the ash trees in the Northeast leaving streets bare and is currently spreading across the U.S. Here in Central and South Texas we have a rising issue with Oak Wilt wiping out sloughs of Live Oaks and Red Oaks. The rapid spread of these species targeted diseases and pest can be limited by increasing the biodiversity of the trees in the urban landscape. An increase in the number of tree species limits the spread by decreasing the number of susceptible hosts for these diseases and pest to thrive.
With the warming climate exacerbating more extreme weather events, it is essential to begin to select trees that are more resilient to the increase in temperatures and droughts. Still these drought hardy trees shouldn’t be the only trees to plant because as we have seen in Texas these past winters that cold freeze snaps are still possible and could wipe out these trees. So, choosing a variety of species that can handle a multitude of climates and provide many wildlife and ecosystem services is essential.
Tips for Increasing Biodiversity
The widely used 10-20-30 rule for tree planting suggest that an urban tree population should include no more than 10% of any one species, 20% of any one genus, or 30% of any family. This has been a subject of debate recently due do to if this rule is followed then 1/5th of the tree population could be loss. This is a significant amount of urban canopy that would be gone. This rule however is still better than traditional monoculture planting in urban environments that has been practiced throughout the country. Recently experts in the arboriculture industry are suggesting a new rule, “look around”. If you look around and see a tree planted nearby, plant a tree of a different species. The more species of different genera or family’s you plant the more biodiverse and resilient your tree population becomes. This is going to be extremely important with the uncertainty of the weather and potential pest and diseases that the future holds. If we want to have a thriving urban forest for the generations to come we need to be more creative and diverse with the trees we plant today.
There are many guides out there to help find new trees and what are best to plant for your site and region. The Texas A&M Forest Service tree planting guide is a great resource to use; www.texastreeplanting.tamu.edu. Also feel free to reach out to our team if you have any questions! We appreciate our clients, colleagues, and friends and want to be a resource for healthy trees across Texas!