Biogeographical & ecological processes, lecture 33

Question 1

Problems with biomes

classification

Answer 1

• can’t map a continuum which is what they are
• in reality there aren’t clear lines between vegetation types
• therefore, biomes don’t exist they are artificial classes along a spectrum

Question 2

Problems with biomes

classifying vegetation

Answer 2

• there are lots of different properties of vegetation
• eg: canopy structure: height, cover, leaf structure
• eg: microclimate: temp. and humidity
• eg: species composition: density, frequency, richness

Question 3

Problems with biomes

distribution of vegetation

Answer 3

• at smaller regional/local scales, other factors control the distribution of vegetation such as, soil/rock variations, topography etc.

Question 4

Problems with biomes

impact of humans on natural biomes

Answer 4

humans have disturbed all natural biomes, mostly to a severe extent

Question 5

Why are biomes useful?

Answer 5

• help to display/explain the global distribution of vegetation
• helps explain relationships between plant communities. climate and other factors (can expand on this)

Question 6

Communities

2 definitions

Answer 6

1. An assemblage of two or more species populations living together

OR

2. An interrelated group of species populations with a functional identity

Question 7

What do communities possess which individual populations don’t?

Answer 7

multiple emergent properties

Question 8

Example of an emergent property

Answer 8

spatial relationship

Question 9

Who has the communities concept been debated between?

Answer 9

Clements and Gleason

Question 10

What is current research interested in, relation to communities?

Answer 10

• complex interrelationships within and between plants

- which communities are instable/vulnerable

Question 11

Ecological variables
(4 interacting groups of factors)

Answer 11

1. Abiotic/physical
2. Biotic (ex. human)
3. Anthropogenic
4. Historical or evolutionary

Question 12

Distribution of a species population is a function of 

2 factors

Answer 12

• resource requirements

- ability to exploit available resources

Question 13

Abiotic factors

Answer 13

Non-living aspects of the environment, chemical and physical

Question 14

Which 2 main abiotic factors do plants respond to?

Answer 14

climate and soil

Question 15

Abiotic factors
(important climatic parameters)
5

Answer 15

• Mean annual temp.
• Amount of temp. fluctuation
• Annual rainfall
• Degree and timing of fluctuation in rainfall
• Potential evapotranspiration

Question 16

Abiotic factors
(important soil parameters)
5

Answer 16

• Depth
• Nutrient availability
• pH,
• Water retention & drainage
• Soil structure

Question 17

Abiotic factors

For every physical parameter, there are min and max levels beyond which…

Answer 17

organisms metabolism can’t be sustained

Question 18

Optimum level of an abiotic factor

Answer 18

A level at which growth and reproduction are maximised

Question 19

Response of one species to an abiotic factor

Answer 19

• similar response over whole species

- but individuals of some species can vary in response to an abiotic factor - different tolerance range

Question 20

Tolerance range of plants to an abiotic factor varies with…
how?

Answer 20

age,

younger plants have lower tolerance

Question 21

Liebig’s law of the minimum

Answer 21

The most limiting factor controls the response of an individual

Question 22

Problems with Liebig’s law of the minimum

2

Answer 22

• Implies that changes in factors other than limiting factor have no affect on plant growth
• Implies that if we remove effects of one limiting factor another will come into operation

Question 23

The presence or absence of a species for a given location depends on whether any individual of the species is …

Answer 23

able to tolerate the set of abiotic conditions at that point

Question 24

Where do more individuals survive at - the extreme optimum conditions or around the average?

Answer 24

around the average

Question 25

Species distribution reflect…

Answer 25

environmental gradients