Arid - KQ2 (why fragile) Flashcards
What are arid ecosystem characteristics?
- 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
What is the impact of climate on ecosystems?
- 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
What are animals that are adapted to arid conditions?
- Camel
- Scorpions
How have camels adapted to arid conditions?
- 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
What plants have adapted to arid conditions?
- Saguaro cacti
- Quiver tree
How have saguaro cacti adapted to arid conditions?
- 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
How have scorpions adapted to arid conditions?
- 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
How have quiver trees adapted to arid conditions?
- Trunk is smooth and impermeable
- White dusty bark rejects heat
- Leaves, few pores, thick cuticles = reduce water loss
- Self amputates branches to reduce evapotranspiration
What are ephemerals?
Plants with a short life cycle which flower after rain and then seed and die
What are succulents?
Store water in fleshy leaves or stems and collect/store water during seasonal rains
What are halophytes?
Plants adapted to growing in saline conditions such as salt marshes and salt pans
What are phreatophytes?
Plants living in dry areas which have root systems to groundwater supplies
Why are arid areas so fragile?
- 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
What is the case study?
Arches National Park, Southern Utah
What are the key facts about Arches National Park?
- 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
