11,000 varieties of trees in North America, but only a few species dot urban landscapes



If you look at the trees, especially in urban areas of Florida, you will usually see southern live oaks or cabbage palms. Logic. These are the two most common species in towns in the Sunshine State.

Indeed, most American cities rely on half a dozen species for the majority of their street and park trees. But there are so many other types of trees you could plant and grow. In North America alone, there are 11,000 species of trees, said Andrew Koeser, associate professor of environmental horticulture at the University of Florida.

Koeser told attendees last month UF Cityscape Summit it is important to plant many different types of trees in cities for them to survive and to increase wildlife habitat, among other reasons.

If you look at Florida, just 10 species make up 63% of Tampa’s interior urban forest, and a similar pattern can be found in other Florida municipalities. But if you plant different types of trees in urban areas, you can reduce maintenance costs and infrastructure damage.

“A lack of species diversity sets the stage for tree loss to diseases or pests that attack certain trees,” said Koeser, a faculty member at the UF/IFAS Center for Research and Education. Gulf Coast.

For example, in Florida, palm trees are often an iconic and abundant feature of the state’s urban areas. The deadly tan, which affects a wide range of palms — but is particularly devastating for date palms — is infecting palms across the state. Mass plantings of the same species repeatedly may be particularly affected by deadly tan, as it has spread to approximately 30 of Florida’s 67 counties.

“This reliance on a small subset of trees is largely driven by market forces, public policy, and a lack of familiarity with underutilized tree species,” Koeser said. “This often results in the loss of trees and the reduction of the air filtering and shading services they provide.”

Other losses include:

  • Remove trees. Tree loss can lead to canopy loss, which results in increased problems such as the urban heat island effect as well as stormwater flooding.
  • Reduced access to green spaces, necessary for human health and well-being.

To bring different types of tree species to cities, Koeser and a colleague at Iowa State University are working with a $50,000 grant from the United States Department of Agriculture to learn how urban areas across the country use various species of trees.

Koeser and Grant Thompson, an assistant professor at Iowa State — along with a set of national collaborators — lead focus groups. They interview arborists, landscape architects, urban foresters, government officials, and representatives of government and nonprofit organizations from across the United States.

Deb Hilbert, a recent PhD graduate from Koeser’s program, led focus groups that included tree growers and buyers as well as city officials, among other stakeholders. They want to determine which of these problems could be solved in the short term.

Researchers hope to pinpoint the root causes of why the same tree species always seem to be planted in cities across the country.

“Is it a communication problem? Is it a biology problem? Is it an economic problem? said Thompson. The focus groups have ended and the researchers are still collecting data.

The mission of University of Florida Institute of Food and Agricultural Sciences is to develop relevant knowledge about agricultural, human and natural resources and to make this knowledge available to maintain and improve the quality of human life. With more than a dozen research facilities, 67 county extension offices, and award-winning students and faculty at the UF College of Agricultural and Life Sciences, UF/IFAS brings science-based solutions to the agricultural and natural resource industries. of the State and to all residents of Florida. . ifas.ufl.edu | @UF_IFAS


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