Climate change, snow mold and the Bromus tectorum invasion: mixed evidence for release from cold weather pathogens

Thinning snow pack cover could alter how snow molds interact with plants over the winter.

In many temperate ecosystems, warming associated with climate change is reducing the depth and duration of seasonal snowpacks leading to dramatic changes in the soil environment. Thick snowpacks insulate the soil from fluctuations in air temperature, whilst thinner snowpacks leave the soil vulnerable to wide fluctuations in temperature, more frequent freezing and thawing cycles, and freezing to greater depths. These changes will undoubtedly have an impact on the plant and microbe communities of these ecosystems and the interactions between them. Snow molds are fungi that grow beneath the snow and can infect plants over winter and have been shown to cause overwinter mortality of certain plant species. However, little is known about how warming (and thinner snow packs) will affect snow molds and their interactions with plants in these ecosystems.

One of the snow melt treatment plots near the Utah State University campus.
Image credit: P. Adler.

In a recent Editor’s Choice study published in AoBP, Smull et al. studied the potential for climate change to promote the growth of a destructive invasive annual grass, Bromus tectorum, by reducing snowpack and releasing the plant from snow mold infections. The authors conducted greenhouse and field experiments to investigate the interaction between early snowmelt and either fungicide addition or snow mold infection of B. tectorum. They found evidence that snow molds do limit seed production but not survival or overall population growth. These results will help to guide management decisions in areas where depth and duration of snowpack will decrease in the future, leaving them vulnerable to invasive species. The authors also highlight that the potential for climate change to reduce the impact of cold weather pathogens deserves further investigation.

Researcher highlight

This paper was a collaboration among members of Peter Adler’s lab group at Utah State University. Danielle Smull, a MS student, designed and performed the field experiment. Nicole Pendleton, working as a summer Research Experience for Undergraduates student, designed and conducted the lab experiment. Andy Kleinhesselink isolated the snow mold and helped mentor both Dani and Nikki. Andy is now a post-doctoral researcher at the University of California Los Angeles.

The Adler lab investigates plant population and community responses to climatic variability and change, with a particular focus on the role of species interactions in mediating climate change impacts. Current work in the lab attempts to rigorously validate predictive models with independent data.

You can read more about the work of the Adler lab here: https://qcnr.usu.edu/labs/adler_lab/

Further reading

Smull, D. M., Pendleton, N., Kleinhesselink, A. R., & Adler, P. B. (2019). Climate change, snow mold and the Bromus tectorum invasion: mixed evidence for release from cold weather pathogens. AoB PLANTS, 11(5). https://doi.org/10.1093/aobpla/plz043