Last Monday I got a chance to go with an EWU grad student named Kristen out to an area where she is thinking about studying management of invasive grasses. The area that she is focusing on is another mima mound area at the refuge: the basaltic mima mounds. I couldn’t hold back from taking a trip out there with Kristen to look at the lichen in that area and learn from Kristen about the different grasses out there, particularly the invasive grasses.
Kristen’s M.S. research is focusing on the affects of different management and disturbance practices on invasive grasses. Her study involves lichens in a way because the cryptogamic soil crusts (lichens, mosses, fungi, cyanobacteria, algae) have been shown to play a role in keeping out the invasive plants while nurturing the seeds and fulfilling the needs of the native plants. Kristen will be altering her plots with fire, with pesticides, foot traffic, and other practices and seeing how these increase or decrease the native grass vegetation.
What lit up in my mind was the potential to see how these disturbances affect the composition of lichen, and if the lichen go through different stages of succession in response to different disturbances. That study would have to be a long term study but I could at least get a baseline assessment of the lichen distribution in those plots, and let someone else pick it up in a few years.
So we took a quick trip out there with her to get a feel for what’s going on out there, and what we found was pretty incredible: a huge patch of Xanthoparmelia wyomingca! I did not notice any Diploschistes like I did over in the alluvial mounds, which seems to indicate a change in soil quality, and I did learn quite alot of grasses, the primary ones of which are invasive. I’m going to briefly go over these here because that will help us identify crusts that are hosting invasive versus non-invasive grasses.
A quick peek at the Turnbull NWR Comprehensive Conservation Plan (see grass species list at bottom of page) shows that more than half the listed grass species are exotic species. It is important to note that exotic species are not necessarily invasive, but many of these grasses are in fact invalsive. These invasives include Poa bulbosa, Ventenata dubia, and Bromus tectorum (the infamous Cheatgrass).
Although none of the native grasses are listed as being endangered or threatened, it is very hard to predict what types of ecological affects may be happening due to the decrease in native plant abundance. The affects may be simple: certain insects may be favored by the changes in spring bloom time and quality, and this could impact the health of our regions forests and farms if these insects become pests. Or they may be complex, causing changes in migration patterns of certain birds and causing a ripple effect throughout North America from a seemingly minor causation factor. Or the effects could be very local, the grasses may be releasing toxins harmful to other plants and microbes (allelopathic chemicals), preventing the establishment of thick cryptogamic soil crusts, thus leading to major erosion issues that affect riparian ecosystems and cause the suspended silt in the water to rip up the tender gills of fish. This all sounds catastrophic, but the effects of loosing native organisms can have vast consequences on an entire ecosystem.
I like to think of an ecosystem as a net that is holding up all the soil and water and living creatures in an area, and its obviously a super strong net because its carrying trillions of tons of biomass. Creating this net are a bunch of threads, and each species is one of those threads and they each have numerous roles to play. And when one of the species is unable to function properly due to a competing invasive organism, or by environmental stressors, that little thread in the net snaps, and the ecosystem becomes a tiny bit weaker. But no fail, the surrounding threads can often figure out how to plug that hole and keep the ecological net intact. However, if these threads snap all over the place, so fast that the other creatures are unable to respond and repair, then the shear weight of the biomass will start snapping more threads. Worst case scenario is that all the soil and water and living creatures will fall into an unorganized massive mess on the floor, the net in tatters, and the humans too. So, although invasive grasses seem pretty harmless, its important to make sure that our native grasses and their roles in our local ecosystems aren’t compromised.
So, going back to lichen, there’ll be a post up soon going over the roles that lichen and cryptogamic soil crusts play in meadow steppe. Stay tuned!