The word monitor derives from the Latin monere “to warn.” As I find myself spending much of my time monitoring rare plants, I reflect on what we’re doing. At its core, I suppose that we are keeping track of these plants so that we can warn everyone if they start to decline. However, we are also watching them in order to celebrate population growth and even population stability, and, more often than not, in order to learn relatively unknown details of their life histories.
In the last couple weeks, the team I’m working with has traveled to an area outside of Kremmling, CO in order to monitor two different plants that only exist within a single Colorado county. Penstemon penlandii has an estimated range of only 5 square miles (NatureServe Explorer), while Astragalus osterhoutii is more widespread, occurring in an estimated 63 square mile area (NatureServe Explorer). Both plants were listed under the ESA when a reservoir was constructed within their range, flooding part of the Astragalus’ habitat and creating concern that an increase in recreation to the area would endanger both species. Further, that Astragalus plants are heavily preyed upon by a native species of blister beetle within part of their range. The plants suck up selenium (a stinky element that occurs in the soil) as a defense against herbivory. Unfortunately for them, the blister beetle has also found selenium to be an effective defense compound, so it eats the plants and stores the selenium. The beetles are immune, but any predators are in for a nasty treat. In fact, ingesting only a few accidental beetles can kill a horse.
Due to this herbivory, the plants in one site seemed to be barely getting by and some were bare sticks, from which all the leaves had been eaten. In our other site, the plants appeared healthy, and in both sites monitoring has shown that the populations are steady. The way that this is possible is because the species is extremely long lived. My mentor did her PhD research on this species, following in the footsteps of someone else who was also studying the population. Yesterday we found one of their old plots. Many of the old tags from the early ‘90s were still in place next to healthy, happy looking individuals. This means that some of these plants (which only grow up to 1 or 2 feet tall) are at least approaching 20 years old. This knowledge is extremely important for managing the population. We now know that it isn’t a crisis if no seed set occurs one year, or if blister beetle herbivory is particularly bad for 5 years. Instead, we simply have to make sure that nothing happens to kill the mature individuals.
I enjoy learning these details about different life histories, and about how a species is adapted for its own unique location and predators. I also appreciate that our data is used to make more informed management decisions. It seems that “to monitor” is in fact much more than simply to warn.
Sama, CO BLM State Office