Figure 19.5 Complex succession. Using tree rings to date the Sitka spruce trees from different sites in Glacier Bay, we can see that older sites experienced rapid colonization by spruce trees after the glaciers retreated, whereas the younger sites experienced slow colonization by spruce trees after the glaciers retreated. Vertical red lines indicate the approximate year of glacial retreat at each site.
Data from C. L. Fastie, Causes and ecosystem consequences of multiple pathways of primary succession at Glacier Bay, Alaska, Ecology 76 (1995): 1899–1916.