<er the cover of darkness, hordes of furry critters emerge from their underground hideouts and venture onto the prairie in search of a meal. Scurrying between grasses and goldenrods, mice and voles must dodge a long list of predators including owls, coyotes, hawks, weasels and shrews just to survive the night. These unheralded rodents often dismissed as repulsive pests are actually some of the most important species in the Arboretum. Besides providing the occasional meal for some of the Arb’s more charismatic residents, small mammalian herbivores play another important role in prairie ecosystems.
According to Biology Professor Dan Hernandez, “Mice and voles are the dominant herbivores in the Arb prairies.” Small mammals have high metabolisms and live at high densities so, in spite of their diminutive stature and short life expectancy, the collective impact of these herbivores can be significant.
“Through their selective feeding and deposition of nutrients in waste, herbivores can influence the composition of the plant community and rates of soil nutrient cycling,” said Hernandez. In other words, think of the prairie as one big communal salad bowl. Some diners are picky and nibble at only their favorite pieces while others have no noticeable preference. For example, the prairie vole (recently discovered in the Arb) tends to consume more roots and legumes than the more widespread meadow vole which prefers the stem and leaf material of grasses. Over time, the plant com- position of a prairie may change as a result of which herbivores are present and what they are eating.
This summer, Hernandez and his lab studied the effects of herbivores on restored prairie ecosystems in the Arb. By using different types of fence to regulate which herbivores had access to different plots, the researchers were able to observe the relative impacts of deer, rabbit, mice and vole herbivory on plant communities. Among other findings, they discovered that deer have a greater impact on prairie vegetation than previously thought. Hernandez hopes his research can inform land managers and contribute to the success of restoration projects.
-Jared Beck ’14 , for the Cole Student Naturalists
