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.
Tropical vs temperate
Tropical climates are warm year-round with wet and dry seasons; temperate climates have four distinct seasons.
Water surplus vs water deficit
Water surplus is where precipitation exceeds evaporation (rainforests/temperate forests)
Water deficit is where evaporation exceeds precipitation (deserts/tundra)
Chaparral
A biome characterized by hot, dry summers and mild, wet winters, with dense, spiny shrubs and periodic fires.
Often powered by a Mediterranean climate.
Adelaide is in this biome.
Deciduous
A deciduous tree is a type of tree that sheds its leaves annually, typically in response to the onset of cooler temperatures and reduced daylight in autumn. This adaptation helps the tree conserve water and energy during the winter months when growing conditions are less favorable.
Savanna(h)
A mixed grassland ecosystem characterized by the trees being sufficiently small or widely spaced so the canopy does not close.
Often has distinct wet and try seasons.
Desert
Notice the one ‘s”.
An arid region with very little rainfall (less than 250mm), extreme temperatures, and sparse vegetation.
Tundra
A cold, treeless biome found in Arctic areas and above the tree line in mountains, with a short growing season.
Taiga
A Russian word for a high-latitude biome also called coniferous (pine) forest or boreal (particularly in Canada) forest.
Emergent
Tallest trees in a rainforest, extending above the general canopy, receiving most sunlight.
Emergents therefore have a competitive advantage for resource acquisition.
Canopy
The upper layer of forests, formed by the the interlocking crowns of trees, providing habitat for numerous species.
Saprophyte
Organisms that digest dead or decaying organisms, mainly fungi and bacteria, helping in decomposition.
Epiphyte
Plants that grow on other plants for physical support but are not parasitic, like orchids and ferns in rainforests.
Buttress Root
Large, above ground roots that provide stability and nutrient absorption in shallow soils, typical in rainforests.
Humus
Organic component of soil formed by the decomposition of leaves and other plant material by soil microorganisms.
Not the dip!
Leaf Litter
Layers of fallen leaves and other organic material on the forest floor, which decompose to form humus.
Detritus
Organic waste and dead parts of organisms. Leaf litter prior to the production of humus.
Detritovore
Organisms that feed on detritus, contributing to decomposition, such as earthworms and millipedes.
Decomposer
Organisms, like fungi and bacteria, that break down dead organic material into simpler inorganic compounds.
Organic Matter
Material that comes from or is made up of organisms, containing carbon. Leaves, branches, dead animals.
Weathering
Big rocks breaking down to smaller rocks in the process of soil formation. Nutrients released.
Leaching
The process by which nutrients are removed from the soil due to rain and water flow.
Infiltration to parts of the soil profile where nutrients are not readily accessible to plants.
Not “leech” (which is a blood sucking parasite)
Gersmehl model
A conceptual model used to describe the relationships between climate, vegetation, and soil in an ecosystem and the pathways (flows) between them.
Decomposition
The process by which organic substances are broken down into simpler organic or inorganic matter.
Mostly aerobic (in the presence of oxygen) and produces CO2 as a by-product.
How the nutrient cycle is impacted when trees are cut down
Soil erosion
More runoff
Nutrient leaching
Loss of leaf litter and organic matter
Disruption of nutrient uptake
Deforestation
The removal of a forest or stand of trees where the land is thereafter converted to a non-forest use.
Nutrients vs minerals
Nutrients include organic and inorganic substances needed for life. Minerals are specific inorganic nutrients (potassium, iron, calcium).
Abiotic conditions in the emergent layer vs the forest floor
The forest floor is darker, cooler and more humid compared to the canopy/emergent layer, which receives more light and wind.
Main differences between a desert and a rainforest
Deserts are arid and have sparse vegetation, while rainforests are highly moist and biodiverse.
What causes ocean currents?
Ocean currents are driven by wind, the Earth’s rotation, temperature, and salinity differences.
Amazon Rainforest
Biodiversity hotspot in tropical South America (spanning 5 countries). Half of the world’s remaining rainforest.
Threats to the Amazon
Climate change (wildfires)
Deforestation
Cattle ranching
Agriculture (soy bean)
Mining
Urban expansion
