1. Journal
Compare and contrast density dependent and density independent limiting factors.

2. ECOSYSTEM FORM & FUNCTION
UNIT 2: ECOLOGY
Succession

3. How do ecosystems form? PRIMARY SUCCESSION
Development of a community from barren rock to productive ecosystem
Occurs in areas that previously contained no life
Can take 1000’s of years b/c soil has to be created first.
Results in a CLIMAX COMMUNITY- final stable community
EX: island formed by volcano, land uncovered from retreating glacier

4. 3. Steps of Primary Succession
Formation of Soil- rocks broken down by
Chemical weathering- pioneer species (lichen & moss) secrete acids that breakdown rock; acid rain
Physical weathering- freezing/thawing of rocks creates cracks
Colonization of plants & animals
Grasses & small plants- shallow soil so small plants grow first.
Shrubs
Pine trees- prefer sunny locations so are first trees to colonize
Deciduous trees- oak, hickory, maple, elm- prefer shade so grow under pine trees & eventually out compete pine trees and take over ecosystem

6. How are ecosystems disturbed/altered?
Goes through secondary succession
Occurs after a disturbance- kills organisms but not soil.
EX: fire, tornado, hurricane, lake becomes forest
Pioneer species- grasses, shrubs
Takes less time- soil is already formed.

7. Secondary Succession of a
Lake