2.4 Biomes, Zonation and Succession Flashcards
Succession
the gradual process by which ecosystems change and develop over time, involving a series of communities or stages that lead to a stable climax community
Primary vs Secondary Succession
Primary succession starts from bare, soil-less environments and develops slowly as soil forms (think volcanic islands), while secondary succession occurs in areas where an existing ecosystem has been disturbed but soil remains, allowing for a faster recovery and regrowth.
Stages of succession
- Colonisation
- Establishment
- Competition
- Stabilisation
- Climax community
Pioneer Species
the first organisms to colonize barren or disturbed environments, possessing traits that allow them to thrive in harsh conditions.
Comprises largely of r-strategists, including “weeds” and annual species.
Climax Community
In steady-state equilibrium.
A stable and mature ecosystem, where the structure and species composition remain relatively unchanged until disrupted by an external event.
Comprises of mostly K-strategists
Seral Stage
one of the sequential communities that develop in an area as it undergoes ecological succession. Each seral stage features distinct dominant species adapted to the specific conditions of the environment at that time.
When does biodiversity peak during succession?
When the most ecological niches are available - usually during the middle stages. Many species are still competing for dominance, and there is overlapping pioneers and climax representation.
GPP similarly peaks in the early/intermediate states.
What happens to biomass as succession occurs?
It increases as community progresses towards climax.
Why is primary succession typically a longer process than secondary succession?
Secondary succession starts with existing soil, seed banks, and sometimes residual root systems, which facilitate quicker plant growth and ecosystem recovery.
Zonation
The spatial arrangement of vegetation into distinct bands or zones in response to differences in environmental factors.
Zonation vs Succession
Zonation refers to spatial differences in ecosystems; succession refers to the temporal changes in community structure.
Environmental (abiotic) gradient
A change in abiotic factors (like temperature, light, pH) over a distance, influencing the distribution of species.
Examples of zonation
Mountain
Rockpool (intertidal zones)
Sand dune
Layers in a forest
Kite diagram
A graphical tool used to display the abundance and distribution of species along an environmental gradient.
ACFOR
A classification system for recording plant abundance: Abundant, Common, Frequent, Occasional, Rare.
Thermohaline Circulation
Also called the Global Ocean Conveyor Belt.
Powered by variations in water density, influenced by temperature (thermo) and salt content (haline).
Involves deep-ocean water movement and upwelling, critical for nutrient and carbon dioxide cycling.
Circulates water globally over hundreds to thousands of years.
Gulf Stream
A powerful, warm, and swift Atlantic ocean current that originates in the Gulf of Mexico and flows into the Atlantic.
Responsible for mild European Climates.
Upwelling
The rising of deeper, cooler, and usually nutrient-rich water towards the ocean surface, promoting biological productivity.
El Nino/La Nina
Climate phenomena in the Pacific Ocean causing global weather extremes; El Nino warms and La Nina cools sea surface temperatures.
Australia receives floods during La Nina and bushfires and drought during El Nino. And the opposite occurs in California and Peru at the same time.
Biome
a distinct geographical region with specific climate, vegetation, and animal life.
It consists of a biological community that has formed in response to its physical environment and regional climate.
A biome encompasses multiple ecosystems within its boundaries.
Latitude
Parallel lines increasing either side of the equator (0 degrees) to the poles (90 degrees)
Tropic of Cancer (23.5 degrees northern hemisphere). Tropic of Capricorn (southern hemisphere).
Arctic circle (66.5 degrees northern hemisphere). Antarctic Circle (southern hemisphere)
Why temperature varies with latitude
Temperature decreases with an increase in latitude due to the angle of solar radiation reaching the Earth.
Tri-cellular model of atmospheric circulation
A model explaining atmospheric circulation, consisting of three cells (Hadley, Ferrel, Polar) per hemisphere.
Powered by changes in temperature (hot, air rises). and pressure (air moves from high pressure to low pressure). Hot air is less dense than cold air.
Hadley cell
Warm air rises at the equator creating a low pressure area near the surface. As it cools, the moisture within it condenses (and precipitates).
The air moves toward the poles and approximately 30 degrees north and south becomes cool and dry. And descends. Creates a high pressure zone. Desert conditions.
The air flows back to the equator across the surface (high pressure to low pressure), and warms. Called the trade winds.
