20 facts about tropical rainforests
Tropical rainforests have existed on Earth for hundreds of millions of years, and most of them now cover parts of the Mesozoic supercontinent of Gondw ...
The tundra is an almost treeless type of biome, characteristic of the Northern Hemisphere. It covers about 11.5 million square kilometers (4.4 million square miles). It is covered with low grasses, mosses, and shrubs. In some regions may appear very sparsely distributed trees.
A characteristic feature of the tundra is the presence of two seasons: winter and summer. Another element of the tundra is permafrost, which hinders the growth of trees.
