L9 - Biodiversity and Biogeography

Question 1

Ecology

Answer 1

The study of relationships between living organisms and their physical environment
Major subdivisions Autecology (individual) and synecology (ecosystem)

Question 2

Autecology

Answer 2

The study of individual organisms of a single species in relation to their environment

Question 3

Synecology

Answer 3

the study of homogenous or heterogenous groups of organisms in relation to their environment

Question 4

What is species richness on islands determined by?

Answer 4

Determined by balance between extinctions and immigration. Larger islands have more species than smaller islands. Number of species decreases with distance from the mainland (isolation), and is eventually constant over time

Question 5

Why is there high extinction rates for small populations?

Answer 5

Low genetic diversity and high chance of stochastic events

Question 6

Stochastic event

Answer 6

random and unpredicted events causing immigration and emigration

Question 7

Name conservation policies aimed at increasing reserves?

Answer 7

Netherlands Nature Network, and Natura 2000 (EU)

Question 8

Succession

Answer 8

specific sequence of plant communities. Visible in time and sometimes space (zonation)
- Primary (new land previously unoccupied)
- secondary (after disturbance)

Question 9

Are climax communities always forests?

Answer 9

No, there are (fire) climax grasslands in south Africa and (fire) climax semi arid rangeland in Kenya

Question 10

theories on succession?

Answer 10

1. monoclimax
2. polyclimax
3. mosaic
4. cyclical climax

Question 11

Facilitation

Answer 11

pioneer species modify conditions that benefit successional species

Question 12

Inhibition

Answer 12

pioneer species modify conditions that hamper the development of late successional species
e.g. reduce rate of N accumulation by increasing denitrification rates

Question 13

Inoculation

Answer 13

using plant soil feedbacks in ecosystem restoration with microbes

Question 14

Feedback in plant invasions

Answer 14

release from specialist pathogens, while receiving benefits from generalist mycorrhizae

Question 15

How did grasslands survive through glaciations?

Answer 15

Species survived 1200 years of glaciation due to the high dispersal ability

Question 16

Why are tropical grasslands in the same location for long periods of time?

Answer 16

Extremely long lived and poor colonisers

Question 17

What is the role of chance?

Answer 17

Describes how the chance of a species reaching a larger island is greater than for a small island, a close island is greater than for a distant island and how extinction rate is higher for small populations

Question 18

What is the role of habitat diversity and heterogeneity?

Answer 18

Describes how heterogeneity is higher on larger islands. This is due to more variation in conditions and resources, thus more species diversity

Question 19

What is the role of time?

Answer 19

Describes how species richness increases over time
- Demonstrated by natural experiment where new island was made (Surtsey Island, Iceland)
- Species abundance can be restored over time

Question 20

What is the role of size/disturbance?

Answer 20

Describes how larger islands are more likely to be disturbed by events such as lightning strike and forest fire. This sets back succession, thus large islands are dominated by early species (e.g. Pinus sylvestris)
- Small islands are less disturbed and thus have more time for succession, hence have greater abundance of late species (e.g. Picea abies).

Question 21

Do mainland islands (e.g. forest ‘islands’ due to deforestation) behave differently to real islands?

Answer 21

No, same theories apply

Question 22

How does primary succession occur?

Answer 22

Occurs on new land, previously unoccupied. Can result from glacier retreat, landslides, formation of new islands by volcanic activity, sedimentation etc.

Question 23

How does secondary succession occur?

Answer 23

After disturbance such as forest fire, land-use change, floods, grazing, herbivory, prescribed burns. Usually occurs faster than primary succession as some seeds may survive in soil (resprouting strategies)

Question 24

Climax community

Answer 24

final stage of succession. It represents a stable and self-sustaining ecosystem that has reached equilibrium under prevailing environmental conditions

Question 25

Characteristics of old growth grasslands?

Answer 25

Contain species which do not occur in young (less successional) grasslands, bud/seed banks and slow growing grass

Question 26

Characteristics of pioneer species?

Answer 26

Able to survive harsh conditions and often modify (facilitate or inhibit) conditions for late successional species.