Fig 9. Transitions to páramo start at 1–1.5 d yr^-1 of frost.

Transitions to páramo from TMCF began at frost frequencies of 1 to 1.5 d yr^-1, highlighting frost as a major factor delimiting equatorial Andean tree lines. (A) a Landsat image composite in which páramo appears in dark pink to magenta-green shades, subalpine TMCF appears in green-violet to green shades, and montane to lower montane TMCF is green; (B) areas exceeding minimum frost frequency thresholds for subalpine (i.e., transitional) or páramo zones; (C) how the frost frequency thresholds were used to map subalpine cloud forest and páramo zones. A frost day is any day that temperatures fall to ≤ 0° C.