Tundra to forest transitions in ALFRESCO

Tundra to forest transitions in ALFRESCO

ALFRESCO 1.0

ALFRESCO 2.0

Tundra to Forest Transition

Tundra to Forest Transition

Colonization of tundra by spruce is a two-step process consisting of:

1) seed dispersal2) seedling establishment

Tundra to Forest Transition

Once established, infilling of tundra by spruce is also a two-step process consisting of:

1) tree growth2) colonization from within

a pixel and/or from neighboring white spruce pixels

Photo: T. Jorgenson

Tundra to Forest Transition

Tundra to Forest Transition

Tundra to Forest Transition

If a fire occurred in the past 3 years, modify seed:seedling ratio by severity:• Low, moderate & high canopy, low surface set to 1:50• High canopy, high surface set to 1:10 (Johnstone & Chapin 2006)

All else in undisturbed tundra set to 1:10 (Hobbie & Chapin 1998)

Tundra to Forest Transition

Tundra to Forest Transition

Tundra to Forest Transition