Have you ever heard the term “noxious herb”? Whenever I bring it up to people that aren’t familiar with the term, I get a quizzical look, and then a funny comment. People might say something like, “Oh, are those weeds like my uncle Joe?” Noxious weeds have nothing to do with your Uncle Joe; they are plant species that are not native to New Mexico, and have negative economic and environmental impacts throughout our state. To be considered a noxious weed in New Mexico, they must be on the State Noxious Weed List. This list can be found on New Mexico Department of Agriculture’s site. bit.ly/3uBQklq.
Native plant species can be outcompeted by noxious weeds. They can eventually replace diverse native plant communities and create monotypic plants if they are not controlled. They do this by using three key attributes.
Seed production is a powerful process: Even noxious weeds can produce large quantities of seed. Musk thistle, Carduus nutans, can produce up to 20,000 seed per plant. Common teasel, Dipsacus fullonum, can produce up to 3000 seeds per plant.
Extensive root systems. One Canada thistle (Cirsium archense) can grow to 3 to 6 feet across in just two growing seasons. Horizontal roots can grow up to 15 ft, while vertical roots can grow 6 to 15 ft deep.
Lack of competition by native plants: No native plants have evolved the ability to compete directly with noxious plants. Because of this, noxious plants have an advantage on any site they are present.
All of this leads to the destruction and loss of native plant communities, adverse impacts on ecosystem function, increased soil erosion, and decreased productivity of agricultural and wild land. Multiple studies have shown that sites dominated with noxious plants have a decreased use rate and presence of wildlife such as elk and Deer, upland birds like Sage grouse or quail, and a wide range of migratory bird species.
Taos County has many riparian habitats that run along streams, acequias, and ponds. There are also moist soil meadows, wetlands, and ground water tables that are quite high. This provides subsurface moisture for diverse plant communities. These habitats are important for migratory birds, native wildlife and plant biodiversity. These habitat types also make up less that 4 percent of the total habitat in the southwest. These habitat types are being dominated by noxious plants in Taos County thanks to the benefits discussed above.
Over the last 15-years, I have seen a dramatic rise in these types of sites infested noxious plants. These sites are slowly disappearing along with the biodiversity they provide. These sites become dominated by noxious plants and monocultures. We begin to see more bare land, higher soil compaction, lower soil moisture, and more soil erosion from wind and water overland. Because the root systems of noxious plants that invade these sites are deep, they can reach well below the top 8 inch of soil, which holds the organic matter, the fungi, as well as the nutrients that our native plants require to grow. It is extremely difficult and expensive to repair soil once it has been lost by erosion or degraded from the loss of a live root.
This scenario is repeated in Taos County as well as in every ecosystem and habitat type. From the high country’s forested lands to the rangelands that border the gorge, as well as the highly productive irrigated agricultural land throughout the county, you can find everything here.
There is a way to deal with this growing problem. It is possible by being proactive and early detection. You can stop the spread of noxious plants by being able to identify them and then quickly remove them. Although a larger infestation may require more time to address, if they are allowed to spread, one thing’s certain: they will continue to grow.
To learn more about how to identify noxious weeds, please visit the Taos Soil and water Conservation Districts site. tswcd.org/. The Taos County noxious weeds list includes descriptions and photos. New Mexico State University has a publication called Noxious & Troublesome Weeds in New Mexico. ces.nmsu.edu/pubs/_circulars/CR698.pdf. This is a great resource for identification. If you are interested in joining the fight against noxious weeds, the Taos County Cooperative Weed Management Area meets every Wednesday. They are always looking to get your help. For more information, call the Taos Soil & Water Conservation District at (575-751-0584).
