Self Sustaining Ecosystems

Ecological succession

Gradual and long-term change in species composition and community structure in an ecosystem

Dynamic ecosystem

Ecosystem that changes over time due to biotic and abiotic factors

Causes of ecosystem change

Catastrophes, seasonal changes, and succession

Catastrophes

Natural or human events that disturb ecosystems

Examples of catastrophes

Volcanic eruptions, forest fires, hurricanes, deforestation

Seasonal changes

Changes in temperature, rainfall, light, and wind that affect species distribution

Succession change

Long-term change in community composition due to organism interactions with environment

Seral stages

Intermediate stages of succession

Sere

Complete sequence of seral stages in succession

Climax community

Final stable community in succession

Pioneer species

First organisms to colonise bare or disturbed areas

Examples of pioneer species

Lichens, algae, mosses

Adaptation of pioneer species

Tolerate harsh conditions and low nutrients

Primary succession

Succession on bare land with no soil or previous life

Examples of primary succession

Volcanic rock, glacial deposits, sand dunes, new ponds

Key feature of primary succession

Soil must be formed first

Rate of primary succession

Slow

Secondary succession

Succession in areas where soil and previous life existed

Examples of secondary succession

Forest fire, flood, deforestation, hurricane damage

Key feature of secondary succession

Seed bank and soil already present

Rate of secondary succession

Faster than primary succession

Difference between primary and secondary succession

Primary starts with no soil; secondary starts with soil present

Succession process

Organisms modify environment making it suitable for new species

Environmental modification

Soil formation, organic matter accumulation, shade, moisture changes

Competition in succession

Better adapted species replace existing species

Plant succession effect

Change in plant species leads to change in animal species

Reason for animal change

Different plants support different herbivores and carnivores

Microhabitat role

Plants create habitats that determine animal distribution

Fungi role

Fungal species change with plant communities

Climax community characteristics

High biodiversity, stable structure, complex food webs, high biomass

Biomass in succession

Increases over time

Species diversity in succession

Increases over time

Food web complexity

Increases over time

Hydrosere

Succession in aquatic environments

Xerosere

Succession in dry environments

Halosere

Succession in salty environments

Lithosere

Succession on rocky surfaces