climate, terrestrial and aquatic biomes Flashcards
(28 cards)
terrestrial biomes
major life zones characterised by vegetation type
ecotones
transition zones between biomes
what are the key abiotic factors that shape composition of animal & plant communities in terrestrial biomes?
- temp
- precip
THIS IS WHY THERE IS VARIATION WITHIN BIOMES
describe the tropical forest biome
- along equator: warm, little seasonal variation
- tropical RAIN forest: 200-400cm rain per year
- tropical DRY forest: 120-200cm rain per year and more seasonal
- vertically layered -> each layer has own unique plant and animal species interacting with ecosystem around them
- v high biodiversity
describe the desert biome
- can be hot (>50℃) or cold (<-30℃)
- precipitation typically < 30cm/year
- low sparse vegetation, characterised by adaptations against desiccation and herbivory
-> leaves and stems of many desert plants have thick, waxy covering…
… keeping plants cooler and ↓ evaporative loss
describe the savanna biome
- warm (>25℃ average/year)
- pretty dry (30-50cm/year)
- seasonal, with pronounced dry season
- grasslands with scattered trees (to varying degrees)
- renowned for large mammals but dominant herbivores are insects
- fire can play important part -> happen in dry season, when high fuel loads allow them to burn over large areas
how do natural fires play an important part in the savanna?
fire in combo with cattle / bison grazing = used to control trees, woody shrubs and invasive species and KEEP GRASSLANDS HEALTHY
- after fire, grazing animals attracted to lush re-growth of grass and concentrate their grazing in burned area
describe chaparral / mediterranean scrubland biome
eg Fynbos in South Africa
- hot summers, mild winters
- seasonal rainfall (30-100cm/year)
- along coasts (but extending inland)
- shrubs and small trees
- high floral diversity (fynbos ~8,500 species)
- fire can play important part
describe temperate grassland biome
- huge areas at center of North America (prairie) and Eurasia (steppe)
- cold winters, hot summers
- seasonal precip 30-100cm
- large grazers -> eg. zebras and gazelles in Africa
- fire
- largely converted to farmland
describe northern coniferous forest / taiga biome
- largest terrestrial biome on earth
- v cold winters
- warm summers
- pretty dry
- LOW BIODIVERSITY
suggest why taiga biomes have low biodiversity
- soil = low on nutrients due to slow decomposition of litter -> even stops during the deep freeze of winter
- only few plant and animal species able to survive it’s winters
describe temperate broadleaf forest biome
- hot summers, pretty mild winters
- varying precip levels (70-200cm/year)
- vertical structure
- higher biodiversity than coniferous forest
- high capacity for recovery (from climate change and humans breaking up biome)
describe tundra biome
- cold and dry
- low vegetation of mosses, herbs, grasses, lichens and dwarf shrubs
- permafrost forms huge carbon store (how will this be affected by warming climate?)
how are lakes and seas divided into zones?
- light penetration
- proximity to shore
- bottom vs water column (epipelagic zone, littoral zone, etc)
what makes up freshwater biomes?
- lakes
- wetlands / swamps
- rivers and streams
-> associated with all terrestrial biomes
-> can vary greatly in physical and chemical characteristics
estuaries
- transition between river & sea
- tidal (linked to sea) – dynamic env
- big variation in salinity
- important breeding / nursery habitats for many marine species
suggest why estuaries are seen as important breeding grounds for many marine species
- good for feeding
- safer than the sea as fewer predators can get there
- lower salinity
- more sheltered
- warmer than ocean as less deep
why is deep water algae red not green?
-> green light refracts more in water
- long wavelengths don’t travel far in water
- red light bounced off before blue and green
- red and brown algae contain extra pigments -> v good at absorbing green and blue light
- green algae live close to surface so don’t need more light
^ doesnt do well in deep water
red and brown algae is OUTCOMPETED by green algae when closer to shore as green algae more adapted to that env
intertidal zones
- periodically submerged (with high tide, low tide) and exposed by tides
- requires specific adaptations for fluctuating conditions -> so v diverse ecosystem
- exposed to fresh air
- zonation from upper to lower shore
ocean pelagic zone
- vast areas of open water (70% earth surface)
- phytoplankton accounts for 50% global p/s
- LACK OF MICRO-NUTRIENTS (e.g. iron) can produce large areas of very LOW PRODUCTIVITY – oceanic deserts
coral reefs
- photic zone of tropical marine env
- mainly near islands
- v v high biodiversity
- v sensitive to climate change
key components of climate
- temp
- precip
- sunlight
- wind
^affect life on global, regional and local levels
global atmospheric circulation and precip patterns
- sun’s rays don’t heat Earth’s surface evenly -> due to curvature
- so solar energy ↑ conc at equator than poles
- at equator: air warmed due to ↑ surface temps so hot, moist air rises
- as air rises, begins to cool as no longer heated by Earth’s surface …
- … so water vapour condenses => ↑ levels precip at equator
seasonality
caused by tilt in Earth’s axis
in summer: UK tilted towards the sun
