How Small Mammal Populations Adapt to Forest Seed Cycles

Trees in northern forests have boom-or-bust-like seed cycles, called masting events, that yield large quantities of seeds in some years but many fewer in others. Small mammals that depend on the seeds for food must adjust their behaviors accordingly to thrive. The ability to adapt on the fly is vital for their survival and for the health of the forest, and it may be tested by the changing climate.

A 12-year study in the Bartlett Experimental Forest led by Rebecca Rowe, professor of natural resources and the environment, examined responses to masting events by five species of small mammals, including shrews, mice and voles. While the researchers found species-specific responses, they also found some important commonalities. In general, many of the species tended to breed later in the season during masting events to coincide with peak availability of new seeds. Conversely, they bred earlier when new seeds were scarce, relying on stored seeds from a more abundant season.

“The way these small mammals adapt to resource availability has a ripple effect throughout the entire ecosystem, impacting everything from seed dispersal to interactions among predators,” says Rowe. “By closely monitoring these patterns, we can anticipate changes in forest dynamics and identify management practices that support long-term ecosystem stability.”