What If Gone

Species → Moose

Moose

Alces alces

524 individuals
Extinction risk Least Concern
Trophic cascadeBoreal forestPredator-prey cycle
Moose (Alces alces)
Photo: Charles J. Sharp, Wikimedia Commons (CC BY-SA 4.0)

What if it disappeared?

Impact Moderate
1 year

From the very first winter without moose, the young balsam fir, birch, and willow shoots that moose would normally have chewed back to the stem go untouched for the very first time — a single winter isn't yet enough to show up in the wood itself, but it's the first season nothing comes along to crop them back.

Extrapolated
Detail

Extrapolation à partir de McLaren & Peterson (1994), qui établissent le lien inverse entre densité d'orignaux et croissance du sapin baumier sur plusieurs décennies, sans isoler ce qui se produit dès le tout premier hiver suivant une disparition complète.

McLaren & Peterson (1994) reconstruct moose density fluctuations on Isle Royale since the 1950s from balsam fir growth rings: when moose become scarce, young tree growth rebounds sharply. Since winter browsing is the direct mechanism behind this relationship, its complete interruption should be felt from the very first winter — but the study measures multi-year trends, not an effect isolated to twelve months.

What's missing to confirm it: A measurement of terminal shoot growth in the very first spring following a confirmed moose disappearance — rather than a retrospective multi-decade reconstruction — is still missing to confirm a first-year effect.

10 years

That relief then shows up directly in the wood: on Isle Royale, when moose become scarce over several years, balsam fir growth rebounds sharply, as recorded year after year in its growth rings — the exact opposite of what happens when moose are abundant.

Documented
Detail

McLaren, B.E. et Peterson, R.O. (1994). Wolves, Moose, and Tree Rings on Isle Royale. Science, 266(5190), 1555–1558.

By analyzing balsam fir growth rings on Isle Royale, where wolves and moose have coexisted in a closed system since the 1950s, the authors show a direct, recurring link between moose scarcity and accelerated young-tree growth — one of the few records this long of a complete trophic cascade, etched into the wood itself rather than reconstructed after the fact.

100 years

Over a century without moose, the island's young fir and birch would likely grow without ever being cropped back winter after winter, forming a much denser, taller forest than any of the natural population lows recorded so far, none of which has ever lasted more than a few years running.

Hypothesis
1000 years

Over a thousand years, this would no longer be just a question of forest density. Smaller browsers, like white-tailed deer or snowshoe hare, would likely take up part of the gap moose left behind, but without ever reaching the same branches or browsing as heavily in winter — the very composition of the island's boreal forest, not just its height, would likely end up diverging permanently from what it is today.

Hypothesis

Documentation

Last verified: August 16, 2026

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