COMMUNITY CHANGE (SUCCESSION) Krebs chap. 21; pages ; 431 “the non-seasonal, directional and continuous pattern of colonization and extinction of species populations on a site”

PRIMARY SUCCESSION Mt. St. Helens pp Lake Michigan dunes pp Glacier Bay pp

SECONDARY SUCCESSION Krebs pp Abandoned fields Forest regrowth Abandoned lots

Mount St. Helens Vegetation recovery

Sand dune ecology Vegetation hummock Beach grass

Fig 21.11Profile of Lake Michigan sand dunes succession “SFT” – space-for-time substitution pastpresent

“Polyclimax” sand dune successions Fig

Krebs Fig Ice recession in Glacier Bay, Alaska, since

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 21.9Change in soil-N Topsoil Mineral soil

1 year later Wildfire

Wind disturbance (“blowdowns”)

Opax Mountain Silvicultural Systems Trial (near Kamloops, BC)

Control burning

Control burn plot

Monitoring succession after fire