Ecosystems under stress: Ecosystems in the British Isles over time

Explain how plant succession leads to a climatic climax community.

Figure 3 shows pollen percentages in a peat core from the British Isles (data are illustrative, written for this paper).

Years before present	Birch	Oak	Grasses
9 000	60	5	10
6 000	15	45	8
3 000	10	25	35

Analyse the data shown in Figure 3.