paper 3- people and the biosphere Flashcards
how is the biosphere important in controlling the water cycle
good source of water vapour into the atmosphere as water is transpired from leaves
helps reduce flood risk as plants/trees intercept precipitation and absorb water which reduces surface run off
interception encourages water to soak into the ground so groundwater stores can be replenished
how does rainfall influence the location of temperate deciduous biomes
in mid latitude areas there is low pressure so high rainfall and no dry season which encourages forest growth
how does temperature influence location of temperate deciduous biomes
avergage temperature never drops below freezing which is good for forest growth
cold winters lead to seasonal deciduous trees rather than coniferous or evergreen
what is malthus’ theory
population will increase faster than resource production as population increases geometrically (1,2,4,8,16) but resources increase arithmetically (1,2,3,4,5)
this will lead to a crisis in food supply and a declining population
what is boserup’s theory
population and resource supply are in balance as farming technology improves to keep in pace with demand eg farm machinery replacing human labour
what year did malthus propose his theory
1798
what year did boserup propose her theory
1965
what is the 2030 perfect storm and who proposed it
john beddington (uk chief scientific advisor) in 2009:
by 2030 we will be running out of resources as food reserves are at a 50 year low but by 2030 we need to be producing 50% more energy, 50% more food and 30% more water
what is the definition of sustainability
development that meets the needs of the present without compromising the ability of future generations to meet their own needs
why are forests so crucial to the hydrological cycle
without forests and no trees there would be:
1) soil erosion as no interception so rain hits soil surface directly
2) less infiltration of water into soil meaning groundwater supplies are lower
3) water gets into river channels much faster
4) flooding becomes more frequent and river is dirty due to soil being washed into it
5) soil dries out quickly so evaporation is reduced so less clouds and less rain
what are biotic factors
living things eg plants and animals
what are abiotic factors
non living things eg atmosphere, water, rock and soil
how do abiotic factors influence biotic factors
changes in abiotic factors can alter ecosystem type which changes conditions for biotic parts
what happens with every 1000m increase in altitude
temperatures fall by 1 degree c on average
what is a biome
global scale ecosystem
what is nutrient cycling
recycling of nutrients between living organisms and the environment
there are nutrient stores in biomass, litter and soil
what is an ecosystem
living and non living components of an environment and the interrelationships that exist between them
what is sandy soil
soil with lots of small air gaps
water drains through it so it feels dry
supports rye, barley and some root crops which have tolerance to drought
what is clay soil
soil that has few air gaps
water doesn’t drain quickly so puddles remain for a long time
supports wheat, beans and grass as it holds nutrients
what is chalky soil
water drains quickly
supports grass and barley
what is peat
doesn’t contain rock particles made from old decayed plants dark, crumbly, rich in nutrients acidic supports rough grazing and forestry
why is biodiversity high in rainforests
the climate is perfect for year round growth and reproduction
rainforests are ancient and have a stable climate so thousands of species have evolved
multiple layers provide numerous habitats
what are features of the emergent layer
hardwood evergreen trees that have broken through the canopy to reach sunlight. monkeys and birds live here
what are features of the canopy layer
dense
home to tree snakes, birds, tree frogs and many more as there is so much available food
air plants grow here
what are features of the understory layer
lots of vines
thick vegetation
dark as most light is absorbed by canopy
birds, butterflies, frogs, snakes, many insects
contains trees with large leaves to capture sunlight
what are features of the forest floor
dark (2% of sunlight reaches floor)
shade loving ferns with large leaves
mammals: jaguar, leopard, tigers, elephants
what are lianas
woody creepers rooted to the ground but carried by trees into the canopy
what are buttress roots
massive ridges to help support the base of the tall trees and help transport water
helps oxygen and co2 exchange by increasing surface area
why do some leaves have flexible bases
helps them to turn to face the sun
why do trees in the TRF have thin smooth bark
allows water to flow down the tree easily and stops other plants from growing in tree surfaces
what are epiphytes
plants that live on trunks and branches of other plants which allows them to make the most of the sunlight in the canopy layer
what are emergents
fast growing trees that out compete other trees to reach sunlight
what is drip trip leaves
water runs off them quickly to prevent moss and algae growing on the leaf surface and blocking light
how are evergreen hardwood trees adapted
tall, slender trunks with no branches
triangular buttress roots to support weight
leaves and branches only at the top where there is sunlight
how are epiphytes adapted
live in the canopy on trees
evolved to get all nutrients from water and air rather than soil
roots dangle in mid air
how are lianas adapted
stems cling to trees and climb up to sunlight in canopy while getting water and nutrients from soil
what are drip tip leaves
thick waxy leaves with drip tips which means water runs off them quickly to prevent the leaf from rotting
how are sloths adapted to live in the TRF
huge flaws so they can hang upside down
fur grows away from feet to help shed rain
green algae growing in fur helps camouflage
how are primates (lemurs and monkeys) adapted
live in canopy where there is most food
long tails for balance
strong claws to grip trees and branches
how are big cats (jaguars, tigers, leopards) adapted
camouflaged as dark and light patches blend in with shade and sunlight
how are birds adapted to the TRF
loud calls as it’s easier to hear a mate than see one
parrots and macaws have powerful beaks to break open nuts
what is the biosphere
the thin layer of living material covering the earth’s surface, made up of ecosystems
where do tropical forests grow
equatorial regions where temperatures are above 28 degrees all year round and there is continual precipitation from convection where hadley cells meet
where are temperate forests found eg UK
40-45 degrees north in areas of high rainfall where polar and ferrel cells meet but have seasonal temperatures
where is the taiga found
far north and are adapted to cope with extreme winter cold and lack of available water
where are deserts found
25-35 degrees north and south at the descending arm of the hadley cell where there is very low rainfall, extremely high temperatures and long sunshine hours
where are grasslands eg tropical savannahs found
places with highly seasonal rainfall which in total is too low for tree and forest growth
where is the tundra found
arctic where temp and rainfall are too low for tree growth and growing season is 3-5 months
what is altitudinal zonation of ecosystems
temperature falls by 1 degree for every 1000m from sea level
in what ways is the tropical rainforest a life support system
provides food, traditional medicine, building materials eg timber, fuelwood from trees either burnt directly or used to make charcoal
what are the energy commercial uses of forests
many have fossil fuels beneath them
gas drilling leads to forest destruction
risk of oil spills and fires
forests are cut down to grow biofuel crops eg palm oil
what are the water commercial uses of forests
large rivers and high rainfall are ideal for hep
involves constructing large dams and flooding forest areas to create reservoirs
indigenous people are often displaced as well as forests being destroyed
what are mineral commercial uses of forests
mining for gold, coltan or iron ore is widespread in many forests
this leads to deforestation
waste from mining pollutes rivers and lakes and the pollution can be carried long distances
what are the 3 regulating services
composition of the atmosphere, soil health/ nutrient cycle and hydrological cycle
what is composition of the atmosphere
plants sequeater co2 from the atmosphere as they grow but release it back when they die and decay
forests store carbon so destroying forests releases co2 and prevents it from being sequestered
plants put o2 back into the atmosphere
what is the nutrient cycle
healthy soils contain nutrients
plants remove nutrients from the soil as they grow which are then passed through the ecosystem food web
dead plant and animal matter is called litter, this decays and returns nutrients to the soil
breaking this cycle by deforestation leads to declining soil health
what is the hydrological cycle
plants intercept falling precipitation slowing it down
plants also absorb water through their roots and prevent surface runoff by slowing down flowing water this prevents flooding and regulates river flow
plants return water to the atmosphere by transpiration which contributes to the formation of clouds and rain
why does the tropical rainforest have such high biodiversity
equatorial climate as this provides ideal conditions for living organisms
what si nutrient cycling
a set of processes whereby organisms extract the chemicals they need for growth from the soil and water then pass them on through the food chain and eventually back to the soil and water
why are food webs important
they support the high biodiversity
they have gradually evolved over hundreds of years
they ensure every creature has its fair share in the available food supply
what are 5 characteristics of the taiga forest
short wet summer long cold dry winters with temp below freezing little precipitation low sunshine hours snow on the ground for months
how are coniferous trees adapted to harsh taiga forest
conical shape and flexible branches help trees shed heavy snow
shed pine needles are acidic and prevent any species of plant from growing
pine needles have a waxy coating to reduce water loss and frost damage
roots are shallow and wide to avoid roots being frozen
why is biodiversity low in the taiga
harsh climate means there are few edible plant species so animal species are also limited.
Many animals migrate in winter or hibernate
what is net primary productivity (NPP)
a measure of how much biomass is added to the biome each year in terms of grams per square metre per year
what are 4 ways in which the taiga is different from the tropical rainforest
lower npp
less nutrient cycling ( slower flows and smaller stores)
less biodiversity
simpler food webs
what are the 2 main causes of deforestation
economic development
population growth
how does population growth link to deforestation
increase in population increases demand for food so to keep up with this land in the trf is cleared for cattle rancing
how does deforestation cause climate change
trees absorb huge amounts of carbon dioxide but when they are felled this stops and more co2 in the atmosphere means more global warming
how does global warming threaten the forest
increase incidence of drought which casues the amazon to emit co2 rather than absorb it
the dry conditions cause forest fires
what are 3 repercussions of droughts
nutrient cycles threatened by decomposers dying as litter stock drying out
food supply and food webs disturbed by leaves in canopy dying
less evaporation and transpiration from dying trees so less cloud and rain
how will climate change impact the rainforest in the long run
cause the rainforest distribution to contract towards the equator and be replaced by tropical grasslands
switch the role of rainforests from carbon sink to carbon source
endanger many animal and plant species so reduce biodiversity
what is the main cause of deforestation in the taiga
logging to provide:
wood pulp for making paper
building timber
wood chips for making chipboard, fireboard and biofuel
why is there less concern about taiga deforestation than TRF deforestation
the taiga biome is the largest in the world- only 8% has been cleared so far
taiga is remote and ‘out of sight’
much lower level of biodiversity so less species are at risk
what are 4 examples of indirect threats to the taiga
pollution of rivers and lakes by the chemcials used in production of wood pulp
strip minin gof minerals
oil and gas extraction with drilling rigs, pipelines and oil spill accidents
hep developments
what are natural reasons for forest fires
often started by lightning strikes during the short summer
thick carpet of pine needles easily catches light
trees contain a resin that burns easily
what are threats to biodiversity in the taiga
illegal logging as forest products are valuable
fires
acid rain- gets into soils and lakes and can stress and kill lakes
pests and disease
what does cites do ( convention on international trade in endangered species )
bans cross border trading in 34,000 endangered plant and animal species. hopes to stop illegal hunting and collecting
what does REDD do ( reducing emissions from deforestationa nd forest degradation)
UN project aims to stop the clearance and degradation of forests on the grounds of checking global warming
what are 3 advantages of CITES
backed by 180 countries
protection applies to species in all biomes
successful in outlawing the ivory trade and trade of rare parrots
what are disadvantages of CITES
protection of species does not halt deforestation
more concern today about reducing causes of global warming
governments have to do the policing and not all developing governments have the resources
species aren’t listed until they are on the brink of extinction
what are 3 sustainable forest management strategies
selective logging- only felling fully grown trees
agroforestry- allowing crops to be grown in carefully controlled cleared areas along with trees that may be harvested for fuelwood or timber
reforestation - collecting seeds from remaining primary forest, growing seeds into saplings in nurseries and then replanting in deforested areas
what is ecotourism
environmentally friendly and alternative form of tourism that seeks to minimise ecological impacts of tourists and consumption of non renewable resources
what are 3 features of a national park
over 1000 hectares
has legal protection and financial support
is open to the public for recreation and leisure but in a controlled way
