Terrestrial Succession Meredith Burke June 13, 2002

DEFINITION * A series of regular, predictable changes in the structure of a community over time.

Succession begins with a simple change. Two types of succession are… PRIMARY SUCCESSION Begins with bare minerals and surface water. SECONDARY SUCCESSION Begins with the disturbance of an existing ecosystem.

Stages of Primary Succession Pioneer Stages: Bare rock, lichens, small annual plants, perennial herbs, grasses Intermediate Stages: Grasses, shrubs, shade-intolerant trees Climax Stages: Shade-tolerant trees, climax community

Factors affecting the rate of succession… 1) Competitive abilities of the species involved. 2) Tolerance to the environmental conditions brought about by changes in vegetation 3) The interaction with animals (particularly grazing herbivores) 4) Fire

New communities start as the result of disturbances in the current environment. Changes to an area often make the environment less suitable for current organisms and more suitable for others. New communities are referred to as PIONEER COMMUNITIES: a collection of organisms able to “eat” bare rock (I.E. lichens) The Beginnings of Succession

Timeline of Terrestrial Primary Succession 1)Primary Community: colonization of organisms on bare rock 2)Lichens break down the rock and and accumulate debris creating a thin layer of soil 3)Small life forms are supported in the soil layer 4)Life forms replace the lichen community

Timeline Continued… 5)New community replaced by perennial plant community 6)Shrubs replaced by shade intolerant trees 7)Shade intolerant trees replaced by shade tolerant trees 8)Climax community is reached

Climax Communities *Stable and long lasting *Larger more diverse populations * Extensive and well defined (AKA a biome) * Results from pioneer and transitional organisms as well as cycling * Changes occur very slowly

Terrestrial Succession At Beaver Lake *Many different stages can be seen *Both manmade and natural *Considered a climax community *Surrounds a kettle lake (MUD Lake) created by the glaciers *Bogs, open fields, and forest are present *Consists mainly of deciduous and evergreen trees