Primary Succession:
- As earth warmed, the glaciers melted and land was lifeless and rocky. Pioneer plants like lichen took a very long time to grow on these rocks. In time, rocks broken down by the lichens mixed with decay lichens formed the first soil. Wind also blew dust, which congregated in small cracks in rocks so that moss and small plants could begin to grow. As more moss and soil forms, grass begins to grow in the area.
Secondary Succession:
- Soil remained and succession followed even after fires and hurricanes. This is faster than primary succession because the soil is already present. In the tundra, this occurs after a fire or a mudslide.