Vegetation and Topographic Signature of Life

Question 1

What are the controls of rainfall and subsequently also of vegetation?

Answer 1

Atmospheric Circulation: Tri-cellular model
Continental Isolation; The more inland the less rainfall
Rain Shadow: Places within it experience little rainfall
Ocean Circulation: Areas that receive colder water will experience less cloud formation

Question 2

What is the rain shadow effect?

Answer 2

A raincloud travelling over a high altitude region will condense on the side it travels over first because of the orographic rainfall. So when they travel over the other side there is little moisture left to condense

Question 3

Give an example of where the ocean circulation has altered rainfall patterns over a small area

Answer 3

In South Africa’s western coast the Benguela brings colder water from Antarctic, whereas on the Eastern coast the Aghulas brings warmer water from equator.

Question 4

What does a lack of vegetation in an area expose it to more?

Answer 4

Aeolian process

Question 5

What are Aeolian transportation processes?

Answer 5

Suspension (Finest particles carried by turbulent eddies over long distances)
Saltation (coarser particles bounce along the surface transferring the momentum to ground impact)
Creep (Larger particles are slowly pushed and slid along the surface)

Question 6

What is the most dominant Aeolian transportation method?

Answer 6

Saltation

Question 7

What differentiates Aeolian transportation methods form fluvial?

Answer 7

Fluvial can transport larger particles

Question 8

What are desert pavements?

Answer 8

Areas where Aeolian processes have removed finer sediment leaving a gravelly pavement of coarser sediment

Question 9

What are ventifacts?

Answer 9

Large structures shaped by abrasion (Sand blasting). shape determined by wind direction and object orientation

Question 10

What are Yardangs?

Answer 10

Larger than ventifacts these are ridges separated by chutes determined by the abrasion of windblown sand

Question 11

What are inselbergs?

Answer 11

Isolated mountains of resistant rock that have been exposed by erosion around them

Question 12

What are sand seas/ergs?

Answer 12

Huge dumps of Aeolian sediment downwind covering a large geographical area

Question 13

What are the most commonly occurring landforms within sand seas/ergs?

Answer 13

Dunes

Question 14

What are the four types of dune?

Answer 14

Barchans
Transverse
Longitudinal
Parabolic

Question 15

Describe Barchans dunes

Answer 15

Isolated, face downwind, form when sediment supply is limited and strong winds

Question 16

Describe Transverse Dunes

Answer 16

Perpendicular to wind direction, form when sediment supply is large, strong steady winds. They are typically a merging of barchans to form long wavy ridges

Question 17

Describe Parabolic Dunes

Answer 17

Facing upwind, common in coastal areas, form when sediment supply is moderate to large and wind direction is constant, Assisted by the presence of vegetation

Question 18

Describe longitudinal dunes

Answer 18

Parallel to wind direction, form when low to moderate sediment supply, minor variation in the wind direction

Question 19

How does vegetation affect the structure of soils?

Answer 19

1. Absorbs moisture to usually where it occurs the upper layer are drier
2. Vegetation secures soil by reducing pore space on slopes mitigating mass movement probability

Question 20

How does agriculture impact vegetation and the hydrological cycle?

Answer 20

It removes vegetation which increases runoff and weaken the soils leading to increased erosion.
Grazing can also cause compaction which increases runoff
Both of these reduces soil quality and thickness

Question 21

How does deforestation affect vegetation and therefore the external river aspects?

Answer 21

It cause instability and erosion causing soil thinning. This increases river sediment load which affects systems at the river mouth

Question 22

How does vegetation influence the internal aspects of rivers?

Answer 22

Vegetation near the banks can increase bank strength. Vegetation may also colonise the middle of the channel leading to island formation. Roughness. Sediment transport and floodplain development.

Question 23

What are ephemeral channels?

Answer 23

These are wide channels occurring in upland areas because the vegetation is sparse due to conditons. The flash-flow rainfall combined with this increases flooding.

Question 24

What are Arroyos channels?

Answer 24

Deep channels created through river incision provoked by climate and land use change

Question 25

What was the conclusion of Tal & Paola’s study?

Answer 25

Without vegetation channel was split in to multiple shallow flows. With, there was one narrow deep flow due to colonisation of bars preventing lateral processes.

Question 26

What is the topographic signature of life?

Answer 26

The idea that the presence of life has a significant stamp on the landscape.

Question 27

Is there a topographic signature of life?

Answer 27

From studying mars, there doesn’t appear to be as there are many landforms that exist there despite the planet not having any indications of previous or current life. Vegetation only appears to tweak the environment.