Chapter 6 - Changes In Ecosystems

Question 1

Primary Succession

Answer 1

The colonisation/ initial inhabitation of an area after a nudation event.
Eg) volcanic eruption or earthquake
R- selected species will be the first to inhabit the area ( mosses and lichens)

Question 2

Secondary succession

Answer 2

Occurs after a primary succession or minor natural disasters like floods or fires
K-selected species will inhabit the area after R- selected species
Eg) Karrie trees

Question 3

Nudation event

Answer 3

Catastrophic events which cause a bare site with no organisms inhabiting the effected area
Eg) volcanic eruption, earthquake, cyclone

Question 4

Climax community

Answer 4

The end point in a community succession where the community has become relatively stable
Eg) old growth forests and rainforests

Question 5

Timeline of important events

Answer 5

Australia separated from Gondwana - 40 million years ago
1st Homo sapiens - 100000 years ago
1st life - 3.9 million years ago
1st of each vertebrate - 500 million years ago - fish, 400 million years ago - amphibians, 300 million years ago reptiles, 200 million years ago - mammals and birds
1st hominid - 5 million years ago
Snowball earth - 800 million years ago
Oxygenation of atmosphere - 2.5 million years ago
Cambrian explosion - 542 million years ago
1st terrestrial plant - 500 million years ago
K-T event - 65 million years ago
Permian extinction - 240 million years ago

Question 6

Timeline of Earth moving

Answer 6

Pangea - Gondwana - Southern super continent

Laurasia - Northern super continent

Question 7

Habitat Destruction

Answer 7

• clearing of native vegetation for urbanisation or agriculture
• reduces the size of habitats which reduces populations of animals and plants due to competition
• land is clear in fragments - habitat fragmentation
• habitat fragmentation cause reduced home range for animals which means they get cut off from food supplies. There is no escape from fires and floods which can cause extinction in animals and it increases risk for disease and inbreeding

Question 8

Eutrophication

Answer 8

• algae blooms
• increased fertiliser use especially high soluble fertiliser including Nitrogen and Phosphorus
• The excess fertiliser runs off into estuary a and rivers
• increase in amounts of nutrients and stagnant water and sunlight makes algae blooms
• this results in a decreased amount of oxygen concentration in the water
• aquatic animals are deprived of oxygen
• also decrease light penetration
• plants can’t photosynthesis

Question 9

Evidence of past change

Answer 9

Using ice cores
Ice cores have preserved the continuous record of past conditions
Trapped gas bubbles and the presence or absence of traces of organisms reveal information about changes in temperature and concentration of atmospheric gases