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

ECOSYSTEM FORM & FUNCTION UNIT 2: ECOLOGY Succession

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

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

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.

Secondary Succession of a Lake