COMMUNITY CHANGE COMMUNITY CHANGE (SUCCESSION)(SUCCESSION)

Krebs chap. 21; pages 403-424; 431Krebs chap. 21; pages 403-424; 431

“the non-seasonal, directional and continuous pattern of colonization and extinction of species populations on a site”

PRIMARY SUCCESSION

Mt. St. Helens pp403-405

Lake Michigan dunes pp416-419

Glacier Bay pp413-416

SECONDARY SUCCESSION

Krebs pp419-422

Abandoned fields

Forest regrowth

Abandoned lots

Mount St. Helens

Vegetation recovery

Sand dune ecology

Vegetationhummock

Beachgrass

Fig 21.11 Profile of Lake Michigan sand dunes

succession

“SFT” – space-for-time substitution

pastpresent

“Polyclimax” sand dune successions Fig. 21-12

Krebs Fig. 21.7

Ice recession in Glacier Bay, Alaska, since 1760

1940

1860

1760

Alders and cottonwoods covering the hillsides

50 years

Spruce coming into the alder and cottonwood forest

100 years

Spruce and hemlock forest

250 years

Fig 21.9 Change in soil-N

Topsoil

Mineral

soil

1 year later

Wildfire

Wind disturbance (“blowdowns”)

Opax Mountain Silvicultural Systems Trial

(near Kamloops, BC)

Control burning

Control burning

Control burn plot

Monitoring succession after fire