Arid - KQ2 (why fragile) Flashcards Preview

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Flashcards in Arid - KQ2 (why fragile) Deck (17)
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1
Q

What are arid ecosystem characteristics?

A
  • Strong winds and shifting sand create unstable surfaces = difficult for vegetation to grow
  • Animals and plants suffer when exposed to long periods of drought
  • Soils thin and infertile = lack of precipitation limits chemical weathering processes
  • high evaporation from rain, runoff and groundwater = saline soil
  • Hard, salt crusts impede root growth
  • Without vegetation = little organic matter created that would normally decompose to release plant material
  • Lack of vegetation exposes soil to wind and water erosion
2
Q

What is the impact of climate on ecosystems?

A
  • High diurnal temperatures/low and unreliable rainfall
  • Strong winds/shifting sands unstable surfaces = hard for vegetation to be established
  • Thin infertile soils = lack of precipitation limits chemical weathering processes = composed mainly of weathered fragments = few nutrients for plant substrate growth
  • Loss of soil by wind/erosion can cause desertification
  • High evaporation from rain runoff and groundwater makes soil saline = hard, salty crusts impede root growth = little organic matter to decompose plant nutrients
  • High temps and low moisture = slow biological activity to break down organic matter
3
Q

What are animals that are adapted to arid conditions?

A
  • Camel

- Scorpions

4
Q

How have camels adapted to arid conditions?

A
  • Large, flat feet to spread their weight on the sand
  • Thick fur on the top of the body for shade, and thin fur elsewhere to allow easy heat loss = large surface area to volume ratio to maximise heat loss
  • Can go for a long time without water (lose very little through urination and sweating)
  • Can tolerate body temperatures up to 42°C.
  • Slit-like nostrils and two rows of eyelashes to help keep the sand out
5
Q

What plants have adapted to arid conditions?

A
  • Saguaro cacti

- Quiver tree

6
Q

How have saguaro cacti adapted to arid conditions?

A
  • Stems that can store water
  • Widespread root systems that can collect water from a large area
  • Spines instead of leaves = minimises surface area = reduces water loss by transpiration
  • Spines also protect the cacti from animals that might eat them
7
Q

How have scorpions adapted to arid conditions?

A
  • Body covered in wax to help tolerate high temps and reduce water loss (can lose up to 40% of body fluid)
  • Low metabolic rate = long time without food
  • Daytime spent in burrows/underground and prey at night
8
Q

How have quiver trees adapted to arid conditions?

A
  • Trunk is smooth and impermeable
  • White dusty bark rejects heat
  • Leaves, few pores, thick cuticles = reduce water loss
  • Self amputates branches to reduce evapotranspiration
9
Q

What are ephemerals?

A

Plants with a short life cycle which flower after rain and then seed and die

10
Q

What are succulents?

A

Store water in fleshy leaves or stems and collect/store water during seasonal rains

11
Q

What are halophytes?

A

Plants adapted to growing in saline conditions such as salt marshes and salt pans

12
Q

What are phreatophytes?

A

Plants living in dry areas which have root systems to groundwater supplies

13
Q

Why are arid areas so fragile?

A
  • Extreme climate (drought, frost, lightening strikes)
  • Flash flooding breaks foliage and stems and removes plants from sides of swollen rivers
  • Urbanisation and road, rail and airport construction
  • Delicate nature of water supple
14
Q

What is the case study?

A

Arches National Park, Southern Utah

15
Q

What are the key facts about Arches National Park?

A
  • Over 1 million visitors annually
  • 2004-2009 = increase of 100,000 cars
  • Day hikers are concentrated on unpaved trails
  • 250m of rain a year
  • Located around 38*N
16
Q

What are the human factors making ANP vulnerable?

A
  • Air, noise and water pollution
  • Introduced species
  • Damage to cryptobiotic crust by footprints or machinery
  • Intense ORV use
17
Q

What are the physical factors making ANP vulnerable?

A
  • Wind blows pieces of broken up crust away = prevents reattachment to disrupted areas, as well as disrupting underlying loose soil
  • Slow rates of growth and recovery
  • Bedding planes in red sandstone rocks = lines of weakness
  • Temperatures fall below 0*C for 7 months of year = freeze thaw and crystal salt weathering
  • Cracks widen by crystallisation