L33 Terrestrial Ecosystems (Deserts, Tundra and Peatlands) Flashcards
where is the tundra biome found?
high latitudes
where is the desert biome?
mid latitudes
what biome are you most likely to find at high altitudes on tops of mountains?
tundra
what does a rain shadow lead to?
arid dry conditions
what is the annual rainfall in deserts?
<250mm per year
what is climate variation in the desert like?
high variation in temperature, 50 degrees during day and below freezing at night
what are three ways organisms in the desert can ‘tolerate drought’?
1) intensification of water absorption
2) reduction of transpiration
3) CAM - Crassulacean acid metabolism photosynthesis
how do plants intensify their water absorption?
shallow roots that are spread very far horizontally or by deep tap roots of >15m
what plant adapts to the desert biome by intensifying water absorption?
agave filifera have dew/fog traps which capture fog moisture
what is an air plant?
they have no roots in the ground, they absorb all moisture from atmosphere through leaves example tillandsia
what are the absorption scales on tillandsia called?
trichomes
how do plants reduce the level of transpiration?
closing stomata
hair around stomata prevents wind flow
how much water is lost via stomata from transpiration/ gas exchange in photosynthesis?
95% of water absorbed is lost
what is CAM?
crassulacean acid metabolism photosynthesis
when is CAM used?
when stomata are closed during the day to prevent water loss
this also leads to reduced photosynthesis
CO2 is taken in at night and is used up the next day during photosynthesis
what are the 3 ways a plant completes photosynthesis?
C3, C4 Cycle and CAM
what is the most popular plant in the desrt biome?
Threophytes (annuals) because they have a short life cycle
what occurs in tundra due to low precipitation?
permafrost
why are there no trees in the tundra?
too windy, cannot root in permafrost
why are there limited species in the tundra?
it is too cold and arid
what is peat?
partially decaying organic matter of plant origin formed under wet anaerobic conditions
how is peat able to form?
OM is produced at a faster rate than at which it can be broken down
what is the accumulation of peat per year in Ireland?
1mm
what layers does peat consist of?
acrotelm layer, water layer and catotelm layer
what is acrotelm?
biologically active top layer of peat
what is catotelm?
biologically inactive and permanently waterlogged bottom layer of peat
what is a fen?
a fen is a minertrophic form of peat which occurs when OM fills a shallow lake
what does minerotrophic mean?
it is highly nutritious for plants
why is peatland popular in Ireland?
high rainfall leads to anerobic conditions
what is a blanket bog?
a form of peat when OM builds up on pre-waterlogged soils
where are blanket bogs found?
in areas of >1200mm rain and >200 rain days
what does ombrotrophic mean?
dependent on atmospheric moisture for its nutrients example blanket and raised bog
what is the challenge for plants in blanket bogs?
fen bogs pH is 7, in blanket bogs it is <4 due to high rainfall
what plant adaptations have evolved for living in peat?
1) Mycorrhizae
2) Efficient Recycling
3) Xeromorphs
4) Carnivorous Habit
5) Efficient ion exchange
what are xeromorphs?
in summer drought they have small leaves and waxy cuticles (prevent water loss)
in winter they freeze over
what is carnivorous habit?
plants that trap and digest insects for nutrients
what is a huge advantage of peat?
it filters water - high efficiency in ion exchange
why can plants not grow on peatlands?
no nutrients
how are peatlands advantagous?
they absorb lots of water preventing flooding
they sequester 25% of global carbon and store it
what will happen bogs with increasing temperatures/ climate change?
they will release carbon
