EESC203 Flashcards
L12: Name 2 societies that have failed due to resource overuse
- Sumer (first major civilisation) ~10000BP
- Zargos mountains (between iran and iraq) - Easter Island (last settled landmass on earth)
- european discovery ~1722
L12: Why is Easter Island a failed society?
After colonisation, population increased from 6000ppl to 30 000ppl.
Islanders survived on root plants, fruit, chickens with pollen record suggesting diverse vegetation.
Trees disappeared, burnt suggested by charcoal. Trees used by islanders for canoes, moai statue movement, depleted for gardens.
Crop yields decreased
- loss of topsoil by erosion - sediment found in swamps
- exposed crops
Agriculture abandoned in 1400AD, resumes in 1500AD, and abandoned again a century later.
WHY??
Large population
Inability to crow crops
Starvation
L12: Why is Sumer a failed society?
Agricultural and technological advancements: irrigation
Irrigation developed, complex society evolved, all fertile land cultivated by 4500BC
population thought to have peaks to around 20 million
Growing population and growing demand
Irrigation led to rising ground water containing high levels of sodium. Evaporation increased accumulation of salt in soil. Wheat is salt sensitive so stopped growing from 2000BC (recorded in clay tablets).
Armies declined, society decline, by 1800BC crop yeild was 1/3 of peak harvest, salinity spread north resulting in agricultural collapse ~1300-900BC.
L12: what are the reasons societies fail?
Jared diamonds 12 indicators of failure
- Deforestation
- Destruction of soil resources (erosion, salinisation, soil fertility loss)
- Water management issues (irrigation)
- Overhunting
- Overfishing
- Introduced species
- Overpopulation
- Increased percapita impact of people
- Anthropogenic climate change
- Build up of toxins
- Energy shortages
- Full humans use of earths photosynthetic capacity
L12: how do societies succeed?
long term planning and considering environmental costs.
L12: When and where did agriculture start
Mesopotamia 11000BC
Animal domestication 11000BC
Crops 9500BC
(wheat, peas, lentils, chickepeas)
L12: Why did humans begin agriculture and why did agricultural
societies out compete other societies.
Agriculture began from increasing populations and colonisation.
Societies outcompete when there is a stored food surplus, enabling technological development, armies and governments to become established.
L12: The links between agriculture, population and environmental
variability
both agriculture and climate is linked to human population growth.
L11: How has the Australian landscape been altered
since European arrival
Pre European
Aboriginal communities had complex and organised use of land. Controlling vegetation and using vegetation mosaics. (fire)
European arrival in 1770. Rapid expansions of pastoral industry. Extensions into arid regions. Mineral exploitation (copper, zinc)
Lead introduced into petrol after 1850 seen in peat deposits in snowy mountains.
L11: When was there a big spike in minerals found in records after collonisation?
1950s: nuclear bomb markers found in records
Environmental contamination.
L11: what was shown in the The snowy mountains records as an example of a
transformed landscape.
Minerals and mining
soils, dust, erosion
L11: What factors underpin the economic and cultural development of Australia after 1770?
Farming and Mining
L10: What is the Anthropocene?
describes the human impact on the planet that will be visible in years to come
L10: What are the stratigraphic markers of the anthropocene?
Temperatures and atmospheric CO2 is currently outside the natural range of variability seen through the holocene.
Globalisation (colonisation of americas ~1600s)
Atomic weapons ~1964
Detected radionuclides in tree rings around this time.
The Great acceleration ~1950s
Post WWII
Dramatic population increase
Global spikes in nadionuclides and fossil fuels
Increased manufacturing
L10: what is the defined ‘golden spike’ marker for the start of the anthropocene?
Crawford lake, canada
L9: How have human populations changed
through the Pleistocene and how have they impacted
the environment
a) Hominid speciation and environmental change during quaternary from dispersals
b) Modern human dispersal
Enviro and cultural influences on human dispersal
- climate change
- Biological change
- Technology and cultural advances
c)Early human-environmental impacts
Mega fauna extinctions and Fire presence - changing ecosystems
d)Limited visible human impacts.
L8: what defines the quaternary and when did it start?
Quaternary began ~2.6mya
Defined by
- large climate instability
- Sea Saw
- species extinctions and spread of humans
- environmental change
L8: When did the Holocene begin?
11.6ka
L8: How is the Quaternary expressed in today’s landscapes?
- sea level change
- hydrological change,
- biological change
- cryosphere change
L8: What drives the Quaternary variability
Feedbacks:
- Albedo
- Greenhouse gases and the carbon cycle, including the solubility pump , the biological C pump,
vegetation change. - Ocean thermohaline circulation
What are the 4 forest fire switches?
- Fule load (biomass)
- Fuel Dryness
- Ignition
- Fire Weather
What are the abiotic factors influencing distributions of Australian ecosystems?
- mean annual rainfall
- water availability
- temperature
What was in the age of the pleistocene. Between what years did these occur?
Age of Megafauna
2.5MYA - 11700ya
What it Australias vegetation like?
Evergreen
- too hot for deciduous plants
What does Australias phytogeography consist of?
high proportions of endemic species reflecting geographic isolation.
What does Autochthonous (native) vegetation in Aus represent?
Highly endemic vegetation adapted in response to climatic pressures and geographic isolation
What happened to Aus from the mid Cenzoic
Continent drifted north and became dryer because it became subject to descending dry air under high pressure cell
Mid-Late cenzoic is described as a period of what?
a period of circum-polar currents, increased thermal gradients between poles and equator.
& Northward drift of aus continent by 6cm/year.
How are the Supercontinents divided
Pangea: all present continenets
Laurasia: N America, Greenland, Europe, Asia
Gondwana: S America, Africa, Arabia, Madagascar, India, Aus, Antartica
What are the factors contributing to distribution of biomes?
- Altitude
- Precipitation
- Soil
- Temp
What are the 2 forms of fire tolerance in plants
- Sprouters (survive fire)
- Epicormic buds
- Rhizomes/Lignotubes - Obligate Seeders (killed in fire)
- Serotiny (smoke released dormancy
- Heat Stimulated dormancy
What is epicormic budding and provide an example.
Epicormic budding:
Epi-buds are bud structures located within bark, hence resprouting can occur above and below groung (meristems)
EG: Eucalypts: Epicormic strands
How do Rhizomes and Lignotubers benefit plants??
When the whole plant above surface is consumed by fire, underground material is protected.
Regenerate via
1. lignotubers
2. root suckers
3. rhizomes
What is an obligate seeder and provide an example
Obligate seeder:
Populations re-established by a new generation recruited from seeds.
EG: Banksia serrata
Smoke released Dormancy
- retention of mature in closed fruit in canopy
- common in shrublands
Heat released dormancy
- Fire genrminates seeds by crackling seed coating (Acacia)
What are some species in the S-H with fire adaptive traits?
- Proteaceae (banksias)
- Myrtaceae (eucalypt)
- Haemodoraceae (kangaroo paw)
explain the priodiverity-biodiversity hypothesis
Fire is a major driver for diversity
2. drives population turn over
3. promoted fire adaptive responses
What happens when a landscape burns too hot and too frequently
?
Fire destroys carbon rich surface above and below ground, dirt loses the ability to absorb and hold water. Increasing flood risk and erosion.
