While typically thought of as having top-down roles in ecosystems, small mammal herbivores bottom-up roles are often underappreciated. As structure builders, small mammals can impact ecosystem function through alterations of soil nutrient cycling. We examined the effects of small mammal-built structure types (hay piles, runways, latrines) on soil and plant biogeochemical cycling across three tundra ecosystems in northern Alaska.
We found that structures play important roles in regulating soil nitrogen levels, regardless of tundra ecosystem. However, different structures influence soil nutrients in different ways. Hay piles increased soil N and plant P, while latrines influenced soil C, N, and P, and runways mainly affected soil N. We also found strong changes in the cover of structures on tundra during different phases of the small mammal population cycle.
Structures built by small mammals have the ability to increase or decrease biogeochemical cycling rates and arctic ecosystem function. Additionally, changes in the abundance of these structures may create pulses of resource availability during the high phase of the population cycle or may aid in maintaining ecosystem function when animals are rare on the landscape. Our work highlights the roles that small mammals play in the bottom-up regulation of tundra ecosystems and the need to include small mammals in our understanding of ecosystem function.
You can read the full paper here: https://doi.org/10.1111/1365-2435.14127
Reference: Roy, A., Gough, L., Boelman, N.T., Rowe, R.J., Griffin, K.L. and McLaren, J.R., 2022. Small but mighty: Impacts of rodent‐herbivore structures on carbon and nutrient cycling in arctic tundra. Functional Ecology.
Text: Austin Roy, University of Texas at El Paso. This paper is a contribution of Team Vole, a group of collaborative scientists seeking to understand the impacts of small herbivores on carbon and nutrient cycling in tundra ecosystems.
Photo credit: Luke Johnson