LWB: Lesson - Ecological Succession (Topic 2.7) đź“–
⏳ Estimated Reading/Watching Time: 7 - 9 minutes
Describe ecological succession and the effect of ecological succession on ecosystems.
Succession
Ecological succession is a transition from one biotic community to another after a disturbance.
Some anthropogenic disturbances are...
- 🏢 urbanization
- 🪓 deforestation
- 🚬 air pollution
Some natural disturbances are...
- 🔥 fire
- đź’¨ wind
- 🏜 drought
- 🌨 blizzards
Primary Succession
Primary succession is the process of initial invasion and progression from one biotic community to the next. This type of succession USUALLY begins in places with no soil.
This could happen in areas where new islands are forming, where glaciers are receding, or after a volcanic eruption, where the only thing left is bare rock in the form of hardened and cooled lava.
Secondary Succession
Secondary succession occurs when an area has been affected by a disturbance, either human or anthropogenic. If an area is cleared and then left alone plants and animals from the surrounding ecosystem may gradually invade the area. This process begins with pre-existing soil, so it occurs much more quickly than primary succession.
Secondary succession is continually occurring all around us. You may see it on the side of the highway, in a neighbor’s yard if they aren’t mowing and weeding it regularly, in a farmer’s uncultivated land, or any number of places.
There are two main types of ecological succession: primary and secondary succession.
Types of Species
Certain organisms serve particular roles in ecosystems. Click through the tabs to learn more about keystone, indicator, and pioneer species.
A keystone species in an ecosystem is a species whose activities have a particularly significant role in determining community structure.
An indicator species is a plant or animal that, by its presence, abundance, scarcity, or chemical composition, demonstrates that some distinctive aspect of the character or quality of the ecosystem is present.
Pioneer members of an early successional species commonly move into an unoccupied habitat and over time adapt to its particular conditions, which may result in the origin of new species.
Effects of Succession
Succession usually begins with a climax ecosystem. A climax ecosystem is an ecosystem that appears to be balanced between all of the species and the physical environment. This implies more stability than actually occurs in nature, but it gives us a place to start. Then, there is usually some type of disturbance, whether natural or anthropogenic, that causes the ecosystem to lose many of the climax species (large trees, etc.). The process of succession then begins to take place. Pioneer species begin growing in the gaps left by the large, climax species and then shrubs begin growing, and then eventually trees replace the shrubs, creating a new climax ecosystem…until the next disturbance.
Succession in a disturbed ecosystem will affect the total biomass, species richness, and net productivity over time.
Primary succession occurs on bare rock and secondary succession occurs where soil is present.
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