The transition from forest to treeless tundra on a mountain slope is often a dramatic one.
从森林到山坡上没有树木的苔原的过渡通常会十分突然和明显。
2
The Canadian Arctic is a vast, treeless polar desert that's covered with snow for most of the year.
加拿大的北极是一个广阔的、没有树木的极地沙漠，一年中大部分时间都被雪覆盖着。
3
Black bear cubs use trees for defense, whereas brown bears and polar bears, which regularly inhabit treeless environments, rely on aggression to protect their cubs.