A systematic assessment of threats affecting the rare plants of the United States

  • Haydée Hernández-Yáñez, Justin T. Kos, Matthew D. Bast, Janeisha L. Griggs, Paul A. Hage, Alex Killian, M. Isabel Loza, Matthew B. Whitmore, Adam B. Smith
  • Biological Conservation, November 2016, Elsevier
  • DOI: 10.1016/j.biocon.2016.10.009

What's the #1 threat to rare plants in the United States? Outdoor recreation!

What is it about?

Across the US about 1 in 8 plants is in danger of extinction, and yet we know very little about what is threatening them. We conducted a systematic analysis to identify the threats facing all the known rare plants in the United States. All told we analyzed over 2700 species.

Why is it important?

We were surprised to find that across the continental US recreation was the most common threat, affecting 35% of species. Most the the impacts from recreation are from off-road vehicles like dirt bikes and 4-wheelers, but a large number were also threatened by activities like hiking, mountain biking, and climbing. The next-most common threats were from residential development, agriculture, invasive species, and construction and maintenance of roads and railroads.


Dr. Adam B. Smith
Missouri Botanical Garden

While we weren't able to measure the severity of threats (how much they actually impact any given plant species), we were able to find how common threats were. I was personally surprised that recreation was so commonly a threat to plants. I love being outside and try to go hiking every weekend. Trails generally won't take me across populations of rare plants, but going off-trail might. So while I'm always tempted to leave the trail, I'll restrain my urge to wander.

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The following have contributed to this page: Dr. Adam B. Smith