Ecological Succession Biology 11(D). Learning Objectives Describe how events and processes that...

Ecological SuccessionBiology 11(D)

Learning Objectives• Describe how events and processes that

occur during ecological succession can change populations and species diversity

Ecological Succession

Population – individuals of a given species in a particular area

Community – all the different populations in an area• Pioneer community – first inhabitants in new

community• Climax community – established community

Ecological succession – orderly change in makeup of a community over time• Pioneer Climax

Ecological Succession

Pioneer Community• Harsh

environment• Biomass

increasing• Energy

consumption inefficient

• Some nutrient loss• Low species

diversity• Fluctuations

common

Climax Community• Favorable

environment• Biomass stable• Energy

consumption efficient

• Nutrient cycling• High species

diversity• Fluctuations

uncommon

Pioneer vs. Climax Community

Ecological succession – land and water Two types:• Primary succession – newly formed area• Secondary succession – area that has been

disturbed

How do events and processes that occur during succession change populations and species diversity?

Ecological Succession

Primary succession in newly formed pond:1. No organisms2. Algae and bacteria 3. Heterotrophic protists and

small invertebrates4. Floating plants (pondweed)5. Larger plants (cattails)

grow around edges

Primary Succession in Pond

Primary succession in newly formed pond:6. Larger animals 7. Becomes marsh, fills in8. Shrubs and trees

Results: • Pioneer Climax• Aquatic Terrestrial• Increased species diversity• Complex food chains

Primary Succession in Pond

Primary succession on rocks:1. Cooled lava rocks form after volcanic

eruption2. Lichens and mosses

appear, dissolve rock, form soil

3. Dead lichens add organic matter

4. Small animals

Primary Succession on Rocks

Primary succession on rocks:6. More diverse plants 7. More diverse,

larger animals

Results:• Pioneer Climax• Barren rock Terrestrial ecosystem• More diverse species and populations

Primary Succession on Rocks

Secondary succession – sequence of changes after a climax community has been destroyed• Natural disasters– Forest fire– Flood

Secondary Succession

Secondary succession – sequence of changes after a climax community has been destroyed• Destruction by man– Clearing land for construction or harvest– Abandoned farmland

Secondary Succession

Secondary succession on abandoned farmland:1. Soil is sunlit and dry2. Weeds are pioneers species

Secondary Succession on Farmland

Secondary succession on abandoned farmland:3. Weeds die, adding nutrients to soil4. More plant species5. Soil shaded by grasses and shrubs6. Pine seedlings 7. Pine forest community (climax)

Results:Abandoned farmland Pine forestMore diverse species and populations

Secondary Succession on Farmland

Summary of Ecological Succession• Species, populations, and communities

change over time• Unfavorable environment Favorable

environment• Few food sources Many food sources• Few species Many species Diverse

populations• Pioneer community Climax community

Ecological Succession

Learning Objectives• Describe how events and processes that

occur during ecological succession can change populations and species diversity

Ecological Succession