Theory 55/Mountain & Alpine/Alpine treeline
Alpine Treeline Is a Season Ratio
The claim
The alpine treeline is set by the ratio of growing season length to frost frequency, not by mean temperature.
01Mechanism
Trees need a season long enough to harden before frost; the ratio determines whether any cohort can establish.
02Prediction
Treeline should track the ratio.
03Refutation
Treeline tracking mean temperature would remove frost.