What If Gone

Species → Northern Red Oak

Northern Red Oak

Quercus rubra

a common, non-threatened species; what varies sharply from year to…
Extinction risk Least Concern
Foundation speciesPublic healthTemperate forestClimate change
Northern Red Oak (Quercus rubra)
Photo: Peter Cooper Jr., Wikimedia Commons (CC0)

What if it disappeared?

Impact High
Two years after a mast year

A heavy acorn crop in autumn causes the white-footed mouse population to surge the following summer, which translates the year after that into a record abundance of tick nymphs infected with the Lyme disease bacterium — a chain reaction spanning two years, not an immediate effect.

Documented
Detail

Ostfeld, R.S., Canham, C.D., Oggenfuss, K., Winchcombe, R.J. et Keesing, F. (2006). Climate, Deer, Rodents, and Acorns as Determinants of Variation in Lyme-Disease Risk. PLoS Biology, 4(6), e145.

A thirteen-year study in the deciduous forests of New York State, a region where Lyme disease is endemic. The white-footed mouse is the primary reservoir of the bacterium responsible for the disease; its summer population, itself driven by the previous autumn's mast crop, in turn determines the abundance of infected nymphs the following year — to the point that the authors were able to link the timing of heavy mast years to Lyme disease risk among the region's residents.

The year following an acorn shortfall

The effect also runs in the opposite direction: when acorns become scarce, the mouse population collapses — and since these mice are an important predator of gypsy moth caterpillars, their absence releases the insect from that pressure, opening the way to defoliating outbreaks.

Documented
Detail

Jones, C.G., Ostfeld, R.S., Richard, M.P., Schauber, E.M. et Wolff, J.O. (1998). Chain reactions linking acorns to gypsy moth outbreaks and Lyme disease risk. Science, 279(5353), 1023–1026.

This study was the first to establish the complete acorn-mouse-deer-tick-gypsy moth chain in the oak forests of the eastern United States. It shows that the same variable (mast seeding) can trigger two cascades of opposite nature depending on whether it is abundant (more mice, more infected ticks two years later) or scarce (fewer mice, more gypsy moths the following year).

Coming decades

In European beech, a different species but one with the same pulsed reproductive mode, warming has already weakened the link between climatic cues and seed production — if a comparable effect affected red oak, the timing of the acorn-mouse-tick and acorn-mouse-gypsy moth cascades documented above could become less predictable.

Extrapolated
Detail

Extrapolation à partir de Bogdziewicz, M. et al. (2021). Climate change weakens the tie between weather and mast seeding. Communications Biology, 4, 459 — étude menée sur le hêtre européen (Fagus sylvatica), pas sur le chêne rouge.

The reference study covers 39 years of data on European beech in England, a species different from the North American red oak but sharing the same reproductive mode of irregular mast years synchronized by climatic cues. No equivalent study on red oak itself has yet measured whether this decoupling also occurs in it.

What's missing to confirm it: A long-term study directly measuring whether warming alters the synchronization or frequency of mast years in red oak, as has been measured in European beech, remains to be conducted.

Documentation

Last verified: August 7, 2026