Primary succession occurs where bare stone or earth is exposed by geologic activity such as volcanism or glaciers. It occurs when all the previous organisms in a habitat are wiped out by some disaster. Common primary successor organisms include mosses, ferns, grasses and insects, depending on the surface left after the previous habitat was wiped out.
Because primary succession is, by definition, the movement of life into an area without life, it is highly reliant on nearby areas to spread new life into it, whether by migration or by seeds and spores. Primary succession happens at different rates depending on conditions. On the Hawaiian islands, where lava flows frequently wipe out existing habitats, the organisms are well-adapted toward quickly colonizing the new stone. However, this occurs much more rapidly in wet areas than in dryer areas.
Primary succession is the movement of new organisms into an empty habitat, but these organisms are relatively temporary. Further succession occurs once the activity of the organisms in primary succession makes the habitat more suitable to other species. Several stages of species often follow, barring another disaster, until a climax community is reached. These communities are usually of long-lived trees or other plants and the animal species adapted to live among them.