在海拔3000米以上，我们到达了林木线，那里只有低矮的灌木和苔藓。

Above 3000 meters in elevation, we reached the ___timberline where only low shrubs and mosses could survive.

徒步时，我们到达了林木线，再往上就看不到树木了。

During the hike, we reached the ___timberline where no more trees grow above that point.