Chapter 5: Changing Ecosystems

Question 1

What is succession?

Answer 1

The progressive change of communities over time

Question 2

What are the two main modes of succession?

Answer 2

Primary and secondary?

Question 3

What is primary succession?

Answer 3

The colonization of plants in a barren place

Question 4

What is a pioneer plant?

Answer 4

A plant capable of invading bare sites, such as a newly exposed soil surface

Question 5

Why are pioneer plants effective colonizers?

Answer 5

They can live under extreme conditions, able to grow in poor soils with low nutrient levels, and have the ability to fix nitrogen into the soil through their relationship with specialized bacteria growing in root nodules. They also have effective seed dispersal, and rapid growth, and rapid reproduction. They are normally small and photosynthetic.

Question 6

What is an r-selected species?

Answer 6

A fast-growing and reproducing organism, often the first to occupy unused resources and living space. They are consistent with a J-curve of exponential growth (pioneer species)

Question 7

What is secondary succession?

Answer 7

The recolonization of disturbed plant communities, regaining equilibrium, although the number and kinds of organisms present may be different

Question 8

What is a climax community?

Answer 8

The end-point in a community succession where the community has become relatively stable, e.g. old-growth forests and rainforests

Question 9

What are K-selected species?

Answer 9

A slow-growing, long-lived typical of those in a climax community

Question 10

What limits a succession from reaching a climax?

Answer 10

Examples include: fire and selective grazing by herbivores helps to create conditions that allow grasslands to persist

Question 11

How to predict the stage of succession?

Answer 11

Refer to table 5.1.1

Question 12

What was the original supercontinent?

Answer 12

Pangea

Question 13

What were the two resulting pieces of Pangea after it split?

Answer 13

Laurasia and Gondwana

Question 14

What caused Australia’s biota distinctive characteristics?

Answer 14

Originally being Gondwana, it separated from Pangea

Question 15

What can be used to observe changes in abiotic factors?

Answer 15

Studying soils, rocks, and ice cores

Question 16

How can ice cores be used to observe past abiotic factors?

Answer 16

By analyzing the air trapped in the ice, the climate and gasses present can be observed

Question 17

How can successional changes be precited?

Answer 17

By collecting data and creating models through sampling and census collection

Question 18

What was the impact of European colonization on Australia?

Answer 18

Due to the Europeans imposing agricultural practices unsuited to the land, disregarding fire management tools, and disregarding the well-adapted animals and their food sources, the environment saw a great decline in sustainability

Question 19

What was the impact of sheep on the Australian environment?

Answer 19

Plants were disappearing, hills were slipping, springs of saltwater were appearing, and erosion from rainfall was becoming evident

Question 20

What has contributed to the extinction of thousands of species?

Answer 20

Destruction of habitats, changes to the atmosphere and water, the stripping of vegetation, and the exploitation of wildlife have all contributed to the extinction of thousands of species

Question 21

What are some main causes for the current unsustainable environment?

Answer 21

Urbanization, habitat destruction, land and soil degradation, salinity, and monoculture practices

Question 22

Since 1750, how much forest and vegetation has been cleared?

Answer 22

20% of forests have been cleared and 90% of vegetation has been cleared

Question 23

What is habitat fragmentation?

Answer 23

The process by which areas of habitat are lost, resulting in a large continuous habitat being broken up into smaller, more isolated habitats

Question 24

How do agricultural animals (sheep and cattle) impact the environment?

Answer 24

Due to hard hooves, they compact the soil which promoted invasive species, reducing tree cover and the topsoil becomes more exposed to abiotic elements (wind and rain). Due to selective grazing, they allow for specific species to grow, reducing biodiversity. Gradually changing the environment

Question 25

What other factors can impact the topsoil of an environment?

Answer 25

Past land clearances, the move to shallow-rooted pastoral grasses, the overuse of fertilizers and heavy machinery

Question 26

What is salinization?

Answer 26

The increased salt concentration

Question 27

What is monoculture?

Answer 27

The agricultural practice of growing a single crop or plant species over a wide area for a large number of consecutive years

Question 28

What are the impacts of monoculture?

Answer 28

Extensive use of fertilizers, pesticides, and herbicides; the spread of disease and susceptibility to changing environmental conditions