The Arctic is the area around the Earth’s North Pole. The Arctic includes parts of Russia, Alaska, Canada, and others, as well as the Arctic Ocean, which is an ocean, but is always covered with ice. Trees will not grow in the Arctic because the temperatures get too cold. The forests stop when they get too far north or too high up a mountain. (Higher places are colder, too.) The place where the trees stop growing is called the tree line or timberline.
The area north of the tree line is not an empty ice field. In fact, the only large ice-covered land is central Greenland, which is covered year-round by ice. The land of the Arctic is around the edges of the Arctic’s border and is usually covered with moss and grasslike plants called sedges.
(edited from: source)