Alien trees that threaten southern ecosystems
The USDA Forest Service Southern Regional Task Force for the Assessment of Nonnative Invasive Species has compiled a list of invaders that they believe to be a very grave threat to forest and grassland ecosystems of the South. This "High Priority" list includes 121 non-native, invasive species -- and 10 of them are trees.
On the list:
- Tree of heaven, ailanthus -- Ailanthus altissima
- Silktree, mimosa -- Albizia julibrissin
- Russian olive -- Elaeagnus angustifolia
- Chinaberry tree -- Melia azedarach
- White mulberry -- Morus alba
- Paulownia, princess tree, royal empress -- Paulownia tomentosa
- Octopus tree, schefflera (in southern Florida) -- Schefflera actinophylla
- Brazilian peppertree (in Florida and southern Texas) -- Schinus terebinthifolius
- Saltcedar -- Tamarix ramosissima
- Tallowtree, Chinese tallowtree -- Triadica sebifera
Eight of these trees also appear on the Invasive Plants of the Eastern United States list at invasive.org.
According to the Executive Order on Invasive Species signed by President Clinton in 1999, an alien (non-native) species is invasive when its "introduction does or is likely to cause economic or environmental harm or harm to human health."
May 22 is The International Day for Biological Diversity, and the theme is "Invasive Alien Species". A booklet, Invasive Alien Species: A Threat to Biodiversity (pdf) can be downloaded. In observation of the day, I've written this post to help increase awareness of some invasive trees that are (or may become) a big problem in the southern United States.