2.4: Biomes, Zonation, and Succession

Question 1

Define biome

Answer 1

Abiomeis a collection of ecosystems that are classified according to their predominant vegetation; they share similar climatic conditions and organisms that have adaptations to the environment.

Question 2

What are the three cells of the tri-cellular model

Answer 2

• hadley cell
• ferrell cell
• polar cell

Question 3

Hadley cell- where is it located and why

Answer 3

• Centred on the thermal equator: the point of greatest heating
• because the equator receives the highest solar radiation which causes rising air and thus a low-pressure zone (called the ITCZ- inter tropical convergence zone)
• the warm air rises to the atmosphere and thus cools down and descends back to the surface and creates high-pressure zones (30 N or S)

Question 4

Ferrell cell

Answer 4

This is a slightly odd cell in that it appears to defy the laws of physics - it has rising air in cooler regions and sinking air in the warmer latitudes

Question 5

Polar cell

Answer 5

• Warm air in the region rises to the troposphere where it tracks poleward and cools
• Cooling in this cell is extreme
• The high pressure creates stable conditions and clear skies

Question 6

Hadley cell

Answer 6

• in the ITCZ (inter tropical convergence zone) the rising air creates high rainfall and regular thunderstorms
• the descending warm air is very dry and creates deserts

Question 7

Draw the tri cellular model

Answer 7

Practica en un papel

Question 8

Earths Tilt and seasons - (HINT: Rotation and revolution)

Answer 8

• The rotation creates day and night.
• The revolution on the tilted axis create the seasons.
• Thecombinationof rotation and revolutiongives varying day length.
• ie. rotation and revolution are not the same

Question 9

Explain the earths rotation:

Answer 9

• Every 24 hours the earth rotates on its axis, this creates day and night
• This impacts biomes because it changes the amount of daylight hours in different locations of the globe
• At the poles day light can be 24 hours in summer and 0 in winter

Question 10

Explain a revolution

Answer 10

• As the earth revolves around the sun on an elliptical orbit it results in the seasons
• The tilt of the earth’s axis results in the sunbeams hitting the surface at different angles
• this impact is less extreme the closer you are to the equator

Question 11

Give an example of ocean current that impact biomes

Answer 11

Example: La corriente del humbolt
1. very cold→ cooling effect on Peru
2. responsible for the dry coastal area of Peru

Question 12

Explain the maritime effect

Answer 12

• It takes twice as long to heat 1 kg of water as it takes to heat 1 kg of land
  therefore: It takes a long time for the oceans to heat up in summer, keeping summer time temperatures lower
• Martitime locations tend to have warm summers and mild winters

Question 14

How do mountains and altitude impact biomes?

Answer 14

• the higher you ascend the lower the temperature
• The rain shadow effect

Question 15

Explain rain shadow effect

Answer 15

A rain shadow is a patch of land that has been forced to become a desert because mountain ranges blocked all plant-growing, rainy weather

Question 16

Revise the biome graph!

Question 17

What are the trends? What are the similarities and the differences?

Answer 17

• Tropical rainforest shows no seasonal variation, then the savannah shows little seasonal variation. the tundra and the desert show a lot of season variation
• Desert and tundra show more extreme temperatures

Question 18

What is a way to show how much water stress there is in a biome?

Answer 18

Precipitation/evaporation (P/E)

Question 19

Describe what does a P/E below and above of 1 (and 1) shows

Answer 19

• P/E below 1 is indicative of water shortages (deserts).
  
  • Rainfall may soak into the soil but high evaporation rates will draw it back to the surface and possibly cause salinization
• P/E ratio of 1 will have good soil moisture conditions leading to fertile soil and good water available to the plants.
• P/E ratio above 1 suggests waterlogged or heavily leached soils.

Question 20

What are k-strategists (in relation to survival strategies)

Answer 20

Animals who produce very few offsprings, but they increase thequalityof them by investing in a lot of parental care.In this case quality means fit for purpose – survive long enough to reproduce themselves

Question 21

What are r-strategists (in relation to survival strategists)

Answer 21

Animals who focus on increasedquantityof offspring at the expense of quality. With little or no parental care survival chances are low but high numbers of offspring ensures at least some survive

Question 22

what is the survivorship curve

Answer 22

• a graph that shows the number of individuals in a population of 1,000, that are expected to survive to a certain age

y axis = number of survivors

x-axis = percentage of maximum life span

Question 23

Type I survivorship curve:

Answer 23

• Indicative of the K-selected species.
• The curve starts out very flat showing a high survival rate in early life.
• ## This long life expectance causes the line to have a sharp drop at the end as the mortality increases dramatically.

Question 24

Type II survivorship curve

Answer 24

• this shows the middle ground with a more or less constant mortality rate throughout the organisms life.
• That is they are as likely to die at birth as they are at old age.

Question 25

Type III survivorship curve:

Answer 25

• this is typical of the r-selected species.
• The curve drops sharply immediately showing very low survival rates after birth.
• Very few individuals make it into later life.

Question 26

Define zonation

Answer 26

• Zonation is the change in a vegetation community along an environmental gradient.
• eg: altitudinal zonation is triggered by a change in climatic conditions due to height

Question 27

Define succesion

Answer 27

Succession is the change in a vegetation community over time

Question 28

What are the stages of succession

Answer 28

Pioneer species
- Bare rock
- Lichens
- Small anual plants and lichens
- Grasses and perenials

Intermediate species
- Grasses shrubs and shade intolerant tress , such as pines

Climax community
- Shade tolerant trees such as oak and hickory

Question 29

How does sucession take place (steps) –> Think about r strategists and k strategists

Answer 29

1. colonisation

a) Pioneer species that are adapted to the extreme conditions

b) r-strategists that are suited to the unstable environment of early succession

2. establishment

a) soil quality becomes better
i. The soil becomes deep enough to provide niches for invertebrates, they breakdown the dead organic matter to form humus which improves water holding capacity

b) competition

    i. Pioneer plants have made the atmosphere more livable and thus abiotic conditions are less extreme → making it so that new plants move in and outcompete the specie for space light and nutrients

    ii. k-strategists are thus more sucesfull

    iii. After competition the sucession stages start to stabilzie and less new species come along

3. Climax community

   a) in a steady-state equilibrium