Living world - ecosystems Flashcards
what is an ecosystem?
a complex natural system made up of plants, animals and the environment - both at small and large scale
what is a biome?
a global ecosystem with flora and fauna that are adapted to their environment
what are biotic features?
living parts - eg. plants and animals
what are abiotic features?
non-living parts - eg. climate, soil and light
Where is Epping Forest (deciduous forest)?
- NE of London
- M11 + M25 run through it
- south of Cambridge
- site of special scientific interest (SSSI)
What is a producer?
link to epping forest
- organisms that convert energy from the environment into glucose
- eg. oak trees in deciduous forest through photosynthesis
what is a consumer?
link to epping forest
- organism that gets energy from eating producers
- eg. caterpillar that eats leaves from a tree or birds or foxes (apex predator)
what is a decomposer?
link to epping forest
- organism that breaks down plant + animal material and returns nutrients to the soil
- eg. bacteria and fungi found in woodland
what is nutrient cycling?
a set of processes where organisms extract minerals for growth from soil and water, pass them through the food chain, and ultimately end back in soil and water
what is a food chain?
shows the direct links between producers and consumers as a single line
what is a food web?
shows the complex hierarchies of interlocking food chains in an ecosystem
what are the levels on food chains/webs called?
trophic levels
what is the apex predator?
the consumer at the top of the food chain/web - it has no predators
what are the 3 components of the nutrient cycle?
soil, biomass and litter
what is nutrient cycling like in deciduous forest?
- large biomass store - tall trees + dense undergrowth
- large soil store - lots of humus
- high flow rate - vigorous cycle of new growth each year
how long does it take for an ecosystem to reach a sustainable balance?
thousands of years
how does change impact an ecosystem?
one small change can seriously disrupt the balance of the ecosystem
what two types of changes affect ecosystems?
- natural changes
- changes due to human activities
what natural changes can happen to an ecosystem?
- changes to the habitat/species
- extreme weather events - eg. droughts can dry up water sources, killing aquatic creatures and other things that depend on them.
what changes do humans make to ecosystems?
- agriculture
- tourism
- fishing
- deforestation
what are the effects of agriculture to a pond ecosystem?
- fertilisers can contaminate water with nitrates and encourage the growth of algae - ponds become oxygen depleted and fish die
- ponds may be drained for farming - all pond life will die
- hedgerows removed to make larger fields - habitats destroyed, altering plant animal balance
- woods cut down - bird habitats destroyed + nutrient cycle affected
Where is Yellowstone National Park?
- in the USA
- in the NW corner of the state of Wyoming
what change had occurred in the Yellowstone ecosystem?
wolves had been exterminated by humans to make it safer for them and for cattle
what was the effect of changing the Yellowstone ecosystem?
losing the wolves meant elk had no predators so there was elk overpopulation which meant the ecosystem became overgrazed
what was done to restore balance in Yellowstone ecosystem?
wolves were reintroduced
what were the benefits of restoring balance in Yellowstone?
- elk were constantly moving - nature had a chance to recover
- cottonwoods, aspens and poplars came back and cleared the river
- beavers returned
- elk population was brought back under control - 20000 to 10000 in 8 years
how are biomes distributed across the world and why?
they form broad belts parallel to lines of latitude due to global atmospheric circulation
what are some causes of biomes?
- solar energy - the poles are heated gently, at the equator heat is more concentrated so it is heated more strongly
- global wind patterns - convection currents (warm ocean moves north, cold ocean moves south)
what causes variation within biomes from east to west?
- ocean currents
- winds
- distribution of land and sea
- altitude
What are the main biomes globally?
- polar
- tundra
- deciduous forest
- desert
- Mediterranean
- temperate grassland
- tropical grassland (savannah)
coniferous forest - tropical rainforest
describe the polar biome
- found at the arctic and antarctica
- dry conditions, low temps of -50C very little life
describe the tundra biome
- between arctic circle and 60-70 degrees N
- cold, windy, dry - short tough grass
- fragile - easily damaged by development
describe the deciduous and coniferous forest biomes
- both found 50-60 degrees north
- coniferous dominates further north - needles reduce moisture loss and maximise photosynthesis
- deciduous trees drop their leaves in winter due to lack of sunlight
describe the desert biome
- 30 degrees N + S of equator
- 1/5 of earth’s surface
- high daytime temps, low nighttime temps + very low rainfall = only very specialised life forms
describe the Mediterranean biome
- isolated biome in S Europe + N Africa
- hot, sunny, dry summers + mild winters = olive groves and citrus fruits
describe the temperate grassland biome
- 30-40 degrees N+S of equator and always inland
- warm dry summers + cold winters = grasses for grazing animals
decribe the savannah biome
- 15-30 degrees N+S of equator
- distinct wet + dry seasons = large herds of grazers and their predators
describe the tropical rainforest biome
- close to the equator
- 6% of earth’s surface
- high temperatures + heavy rainfall - ideal conditions for vegetation
