Answer/Explanation:
The diagram below shows the various stages of ecological succession that occurs over time and how an ecosystem forms from bare surfaces like an area of land covered by lava as a result of volcanic eruption.
The changes in the group of species that occur overtime is depicted in the "six stages" graph which can be described as follows:
1. The first line in the graph shows bare rock which initially supports no life forms.
2. The second stage is dominated initially by pioneer species such as mosses, lichen, which usually produce many small spores and seeds that are dispersed over large area of land. They colonize the bare rocks and their activities help in the breaking down of the rocks to form soil. They also help in the formation of organic matter, and with time, enable the growth of herbaceous plants such as grasses and ferns.
3. At stage 3, herbeceous plants like grasses and herbs that are usually annual plants, gradually replace the mosses and lichen, followed by perrenial herbaceous plants. Further build up of organic manure occurs, thereby encouraging more species of organism to dominate the land
4. At stage 4, woody pioneers that are more later than grasses begin to form and dominate the area with time as more group of species are added.
5. At stage 5, Fast growing trees that are shade intolerant begin to emerge and populate the area, in the presence of herbs and other vascular plant species.
6. At stage 6, a climax community is formed as shade tolerant trees emerge.
