The timberline is the edge of the forest on a mountainside. Above the timberline, reach the timberline, below the timberline.
It is where cold, wind and short seasons stop trees growing upright, and the last trees before it are often stunted and bent by the wind. Its height falls as you go towards the poles — it is thousands of metres up in the tropics and at sea level in the far north. Note treeline, the commoner word.
1nountimberlineThe edge of the forest on a mountainside.
“Above the timberline, there was nothing but rock, snow and a few low bushes.”
timberline is a boundary.
Timber plus line. Treeline is the more usual word outside North America.
From timber + line.
Etymology from Wiktionary, CC BY-SA