Ecological Succession and Fire Ecology Flashcards
What is ecological succession?
A series of progressive changes in the species that make up a community over time.
When does primary succession occur?
When new land is formed or bare rock is exposed, providing a habitat that can be colonised for the first time.
Give an example of primary succession.
May take place following the eruption of volcanoes in Hawaii. As lava flows into the ocean, new rock is formed.
When does secondary succession occur?
When a previously occupied area is re-colonised following a disturbance that kills much or all of its community.
Give an example of secondary succession.
Oak and hickory forests cleared by wildfire. Wildfires will burn most vegetation and kill animals unable to flee the area. Their nutrients, however, are returned to the ground in the form of ash. Since a disturbed area already has nutrient-rich soil, it can be recolonized much more quickly than the bare rock of primary succession.
What is the climax stage?
The climax stage is the last stage of an ecosystem. It is when the ecosystem has become balanced and there is little risk of an interfering event or change to mutate the environment.
Give an example of an ecosystem in the climax stage.
Rainforests and deserts.
What is tricky about climax stages?
Given human development, any ecosystem that is in the climax stage now holds the risk of being destroyed and going backward in the stages.
What are fire regimes?
Traditional practise of Aboriginal and Torres Strait Islander people where they control burn segments of bush.
What are fire regimes determined by?
- The season in which fires occurs
- The intensity of the fires
- The frequency of fires in a given period over time.
What was the purpose of controlled burnings?
- Encouraged grassland ecosystems to persist which meant for easier hunting and stimulated growth of edible plant species.
- When fires become infrequent in areas often invasive grass species can become dominant, these build up over time which increases the fuel load and therefore intensity of fires when they occur naturally.
Are controlled burnings still used today?
Yes the controlling of fires is still used today because of its advantages.
What is the relationship between climate change and fire?
Incidence of fire is increasing as global temperatures rise:
- Increased fuel load due to larger areas of dry plant material
- Higher temperatures leading to more intense and more frequent fires
- Larger areas being burnt
- Even plants with adaptations to fire cannot survive the hotter fires
What are the 8 benefits of ecological prescribed burns?
- Stimulates the germination or flowering of particular plant species.
- Modifies the habitat of individual wildlife species.
- Promotes overall ecosystem resilience through regeneration of particular vegetation formations.
- Regeneration of fragmented landscapes where there is an absence of fire such as peri-urban grasslands.
- Weed control.
- Treatment of key threatening processes ie. disease.
- Mitigates the risk of wildfire burning fire sensitive ecological assets.
- Removes larger slow growing tree species so that other species have space to grow.
Describe how some plants have developed adaptations to fire in order to survive.
- Obligate seeders die when their leaves are scorched however rely on seeds which are triggered to germinate after a fire event, meaning they are able to survive after a fire.
- Re-sprouters may appear destroyed but are able to re-sprout from lignotubers or buds under their bark, meaning they are able to survive after a fire.
