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Environmental Science 315 > C6 Change of Ecosystems > Flashcards

C6 Change of Ecosystems Flashcards

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1
Q

LAYERS OF THE ATMOSPHERE: troposphere
- order
- features

A

1st layer
- approx 10-15km high
- gets colder further up, air gets thinner
- weather + clouds occur in this layer

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2
Q

LAYERS OF THE ATMOSPHERE: stratosphere
- order
- features

A

2nd layer
- gets warmer
- contains ozone layer (absorbs harmful UV rays from sun)
- drier than troposphere

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3
Q

LAYERS OF THE ATMOSPHERE: mesosphere
- order
- features

A

3rd layer
- coldest layer
- meteors/rock fragments burn up on entry

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4
Q

LAYERS OF THE ATMOSPHERE: thermosphere
- order
- features

A

4th layer
- hottest layer
- auroras occur within the layer
- space shuttle orbits

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5
Q

LAYERS OF THE ATMOSPHERE: exosphere
- order
- features

A

5th final layer
- very thin
- made up of He and H

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6
Q

Describe the timeline of the atmosphere and how gas concentrations have changed over time.

A

EARTH FORMS (4.6 BYA)
- by volcanic activity
- very hot
- mostly CO2, with N2, some H2O + methane

EARTH COOLS
- H2O cools, forming oceans
- CO2 dissolved into oceans, taken in by organisms
- CO2 confined into sedimentary rock + FFs

PLANTS EVOLVE (2.7 BYA)
- Phs takes in more CO2, produces more O2
- other gases (methane, ammonia) reacted with O2, and decrease in quantity
- N is very stable, and has built up over time

NOW
- atmosphere mostly N2 (79%), O2, with small amounts of H2O, CO2, and other gases

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7
Q

State the types of evidence available for past climate change (9).
- provide some info on how they are used

A

Rock types + locations
- rocks in an area give info about past climates (e.g. ancient coral atolls in areas far from oceans)

Ancient landscapes (changes/structure)
- landscape shapes show climates of the past (e.g. U shaped valleys show the area was glaciated)

Fossils
- fossils indicate past climates by the organisms that lived there (e.g. ammonites found in a desert, coral found in a forest)

Sea/lake evidence
- changes in water lvls give an indication of past climate

Dendrochronology (tree rings)
- tree ring dating indicates whether a climate was wetter (rings are thicker)

Historical/archaeological records
- cave paintings may suggest species that the current climate would not support (e.g. grazing animals in Sahara)

Coral/sediment cores
- cores taken from coral/sediments show evidence for climate when they were formed, for 100s-1000s of years ago
- combined with fossils, can provide continuous data

Atmospheric monitoring
- baseline gas conc.s are monitored at: Tas (Sth Hemi), Hawaii (Nth Hemi)
- measure greenhouse/ozone depleting gases in clean air enviros
- critical for global monitoring

Ice cores
- very robust evidence
- cores drilled from ice caps
- past air is trapped in the ice from snow falling, this is analysed
- O2 indicates the temp of the past (less heavy O2 means cooler temps)

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8
Q

trade winds

A
  • winds that circle the Earth near the equator
  • EAST TO WEST (clockwise)
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9
Q

ENSO (El Nino Southern Oscillation)
- what?
- what is the graph that represents it

A
  • predictable changes in atmospheric circulation (weather/wind/clouds) between North Australia and South America
  • a cycle, around 4-7 years, from which weather predictions can be made
  • known as a ‘climate driver’
  • it oscillates between neutral, El Nino, La Nina

SOI (Sthn Osc Index) GRAPH
- gives an indication of development + intensity of El Nino/La Nina
- larger peaks show when cycle is in El Nino/La Nina

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10
Q

Describe the neutral phase of ENSO.
- what
- Walker Circulation

A
  • in the phase more than 1/2 the time
  • strong trade winds blow E to W
  • causes upwelling of cold, nutrient dense water in Sth America (good for fishing)

WALKER CIRCULATION
- warm air over Nth Aus rises
- condensation/clouds causes rain
- dry air blows on T winds to Sth America
- gets cooler, descends
- is carried on T winds back to Aus
- gets warmer, cycle begins again

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11
Q

Describe the La Nina phase of ENSO.
- general effects
- Aus
- Sth America

A
  • WALKER CIRCULATION INTENSIFIES - the ‘extreme’ version of neutral phase
  • trade winds are stronger
  • positive feedback loop (drives itself)

AUS
- warmer H2O in oceans in Nth Aus
- increased rainfall/clouds
- atmospheric instability: storms, cyclones, flooding

STH AMERICA
- colder H2O in oceans
- less rainfall, drought
- stronger upwelling (good for fisheries)

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12
Q

Describe the El Nino phase of ENSO.
- general effects
- Aus
- Sth America

A
  • TRADE WINDS WEAKEN/REVERSE
  • warm H2O drifts to Sth America

AUS
- colder H2O in oceans in Nth Aus
- less rainfall, drought, bushfires, heatwaves

STH AMERICA
- warmer H2O in oceans
- increased cloud/rain, flooding
- less upwelling (bad for fisheries)

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13
Q

biodiversity

A

the variety within all species and the ecosystems within they live

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14
Q

levels of biodiversity

A
  • Genetic: differences among individuals/populations, due to sexual reproduction
  • Species: the variety of different species within an ecosystem
  • Ecosystem: all the communities, habitats and processes within different ecosystems
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15
Q

Explain the importance of biodiversity (3)

A

INTRINSIC VALUE
- everything has the right to exist

VALUE TO OTHER SPECIES/ECOSYSTEMS
- Genetics variation: increases resilience to change, increases chance of gaining useful adaptations
- Habitat variation: provides opportunities for competition, adaptation + evolution, conserving habitats preserves species/genetic diversity

HUMAN VALUE
- Economic benefits: wide variety of materials, wide gene pool reduces risk of diseases wiping out farmed products, warns us against use of some toxins (e.g. DDT), provides pharmaceutical services
- Ecosystem services: pollination, nutrient cycles, pest control via predators, maintain stable atmosphere (CR + Phs)

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16
Q

biodiversity hotspots

A
  • 36 identified worldwide
  • support around half of the world’s plants and animals
17
Q

State the threats to biodiversity.

A
  • natural events (e.g. ice age, eruptions)

Human causes
- habitat loss (deforestation, plantations, urbanisation)
- invasive species
- overharvesting/ hunting / fishing
- pollution (damages habitat + organisms)
- climate change (many effects: temp change, coral bleaching, frequent fires, etc)

18
Q

Explain why invasive species are so successful once established.

A
  • ecosystems, over millennia, evolve to reach a balance between species interactions
  • there are limiting factors that restrict the size/range of all species
  • however, different habitats have different limiting factors
  • when a species is introduced, the new limiting factors may fail to restrict its growth
  • results in the species outcompeting all natives
  • ecosystem may collapse
19
Q

INVASIVES: Feral Cats
- biology
- how introduced?
- successful due to
- impacts (2)
- control methods (3)

A

BIOLOGY
- domesticated cat but larger
- nocturnal and live almost anywhere
- eat any prey they can catch (marsupials, reptiles, rodents, birds etc)

INTRODUCED
- as domesticated pets in 1800s: escaped into wild
- deliberately introduced to control pests (rats, rabbit, mice)
Successful:
- lack of apex predators in Aus
- abundance of prey due to this, not adapted to deal with high hunting efficiency of cats
- cats have higher reproduction rates than most Aus marsupials

IMPACTS
- loss of species: extinction, many under threat
- prevents reintroduction programs of species
- toxoplasmosis: makes prey lose natural fear of cats, destruction of the population
- affects livestock/agriculture populations

CONTROL
- trapping, shooting, fences to protect areas
- baiting (may affect native species)
- grooming traps: spray poison onto fur

20
Q

INVASIVES: Rabbits
- biology
- how introduced?
- successful due to
- impacts (3)
- control methods (3)

A

BIOLOGY
- live in most places, create warrens
- nocturnal

INTRODUCED
- 1850S for hunting
Successful:
- very high reproductive rates compared to natives
- high tolerance to lack of water/food
- lack of apex predators in Aus

IMPACTS
- comp with native herbivores: create barren areas, no vegetation
- wipe out plant pop.s rapidly
- barren soil vulnerable to erosion + infertility

CONTROL
- fencing, shooting, trapping, exploding/digging up warrens
- baiting
- myxoma virus (biological control): introduced to deal with rabbits exclusively, there is now some resistance, but still effective
- rabbit reproduction is too rapid to ever slow pop. growth

21
Q

INVASIVES: Blackberries
- biology
- how introduced?
- successful due to
- impacts (5)
- control methods (4)

A

BIOLOGY
- fleshy druplets each containing a seed
- no natural predators (likely due to spikes)

INTRODUCTION
- in 1840s, for eating fruit, making hedges, + controlling soil erosion along rivers
Successful:
- no predators, spikes, many seeds, fast spread

IMPACTS
- form dense thickets, dominating native species
- limit access to areas
- decrease land productivity
- alter water flow
- provide habitat to pest animals

CONTROL
- leaf rust (biological control): slows growth rate
- staged removal: gradually remove + replace with native plants (better for native animals using plants as shelter)
- goats (invasive) eat blackberries
- herbicides (animals may eat the fruit and be affected)

22
Q

INVASIVES: Long-spined Urchin
- biology
- how introduced?
- successful due to
- impacts (2)
- control methods (4)

A

BIOLOGY
- herbivores with long spines
- lives on rocky coastlines
- females produce millions of eggs a year

INTRODUCTION
- climate change and warming waters
- allowed urchins to move further south + reproduce more
Successful:
- overfishing of large crayfish (their only natural predator)
- the legal catching size is smaller than they need to be to kill an eat an urchin

IMPACTS
- overgrazing of kelp/coral: reduces habitat for native species, prevents absorption of CO2 from water, increases climate change
- grazing creates barren areas of no life

CONTROL
- culling or urchins by hand by divers
- establishing a market for eating urchins
- increasing populations of crayfish by dropping into areas
- reducing number/size of crayfish caught

23
Q

in situ vs ex situ conservation

A

IN SITU
- conservation of species in their natural habitat (nature parks, reserves)

EX SITU
- conservation in isolation to their natural habitat (botanic parks, zoos, seed banks)

24
Q

Describe the purpose, pros and cons of in situ conservation.

A

PURPOSE
- conserve species in their natural environment

PROS
- species have all their required resources
- more space
- greater genetic diversity
- evolution will occur
- cheaper to maintain
- non-target species will be protected due to species interactions

CONS
- large land may be hard to manage/police from illegal actions
- land may need restoration
- invasive species may affect the ecosystem
- edge effects if the land is small (design/shape of the land may not be efficient)

25
Q

Describe the purpose and issues with the types of ex situ conservation.

A

PURPOSE
- a last resort for endangered species that cannot recover in the wild
- good for species that are easily bred, harder for specialised species

ZOOS + BOTANIC GARDENS
- very small gene pool = low genetic diversity
- inbreeding is a problem, resulting in a greater chance of negative recessive traits
- aims to reintroduce back into the wild, but the natural enviro may have disappeared

26
Q

DAY AND NIGHT
- provide examples of how day/night cycle affects terrestrial ecosystems (producers + consumers)

A

Predators
- night: decreased visibility and stealth = efficient hunting
- day: animals that rely on sharp eyesight (eagles) must hunt in daytime

Producers
- night: lack of light means no Phs
- day: increased light = increased Phs and productivity

Environmental Science 315 (5 decks)

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