ecosystems and tropical rainforests Flashcards
what is an ecosystem
a unit that includes all the biotic (living) parts and the abiotic (non-living) parts in an area
how can the organisms in an ecosystem be classed
as producers, consumers or decomposers
ecosystem definition
a community of plants and animals that interact with one another and their physical environment
examples of biotic organisms
- fungi
- plankton
- bacteria
- algae
- insects
- mammals
examples of abiotic organisms
- soil
- sunlight
- heat
what is a micro-habitat
a very small scale system, such as a tree or your intestines
what is a biome
a global scale ecosystem, such as the rainforests or deserts
what is a biosphere
all the living organisms in the world and their physical environment
what is a producer
an organism that uses soil energy to produce food
what is a consumer
an organism that gets its energy by eating other organisms
what is a decomposer
an organism that gets its energy from breaking down dead material, including dead producers, dead consumers or fallen leaves
example of a small-scale uk ecosystem
Reigate Heath, Surrey
producers in reigate heath
- heather -> a dominant plant that thrives in acidic, nutrient-poor soils, providing food and habitat for many species
- gorse -> another key shrub, offering shelter and food for insects and birds
primary consumers in reigate heath
- herbivores that feed directly on producers -> rabbits
- various insect species such as butterflies
secondary consumers on reigate heath
- carnivores and omnivores that prey on primary consumers -> birds, such as the Dartford warbler, which feeds on insects
- small mammals, like the weasel, which preys on rabbits and rodents
tertiary consumers at reigate heath
- top predators in ecosystem -> birds of prey like the kestrel, hunting small mammals and birds
decomposers in reigate heath
- fungi -> various species decompose leaf litter and dead wood, releasing nutrients back into soil
- bacteria -> essential in decomposing organic matter and facilitating nutrient cycling
- detritivores -> insects such as beetles and worms that feed on decomposing plant and animal material
what do the interrelationships in reigate heath show
they show the dependency of species on one another and their environment
what is nutrient cycling
1) when dead material is decomposed, nutrients are released into the soil
2) the nutrients are then taken up from the soil by plants. the plants may be eaten by consumers
3) when the plants or consumers die, the nutrients are returned back to the soil
4) this transfer of nutrients is called nutrient cycling
what are the two main sources of nutrients in an ecosystem
- rainwater washes chemicals out of the atmosphere
- weathered rock releases nutrients into the soil
what does a food chain show
what eats what
what does a food web show
lots of food chains and how they overlap
what is a biome
a large scale ecosystem
what factors influence the distribution/location of biomes
- latitude
- precipitation
- altitude
location of coniferous forest
roughly 60 degrees north
characteristics of coniferous forest
- cold and dark winters
- quite warm summers
- coniferous trees are cone-bearing and many are evergreen so that they can photosynthesise immediately after the winter
location of deciduous forest
roughly 50 degrees north
the natural ecosystem for the uk and much of western europe
characteristics of deciduous forest
- deciduous trees shed their leaves in winter to retain moisture
- the climate is more moderate, with mostly mild and moist conditions and a few extremes of temperature
location of deserts
roughly 30 degrees north and south of equator
close to tropics of cancer and capricorn
characteristics of deserts
- sinking air in these latitudes suppresses rain formation, leading to arid conditions
- hot in daytime but cooler at night, due to lack of cloud cover, allowing heat to escape
- plants and animals have to be very well adapted to cope with these harsh conditions
location of mediterranean
roughy 40-45 north of the equator
characteristics of the mediterranean
- hot and dry summers
- wet and mild winters
- vegetation includes citrus fruit trees, oaks and olives
location of polar/tundra
arctic and antarctic and high latitudes, such as canada and siberia
characteristics of polar/tundra
- extremely cold throughout the year in polar regions
- cold winters but quite warm, brief summers in tundra regions
- limited precipitation
- very fragile and easily damaged by human activities
location of tropical rainforests
close to equator
wide-spread across asia, africa, and south america
characteristics of tropical rainforests
- concentrated energy from sun heats the moist air, which rises to produce heavy rainfall
- this, combined with high temps means the conditions are ideal for plant growth
- rainforests cover 6% of the earths surface and over 50% of the worlds animals and plants live in this ecosystem
location of savannah
between 15-30 degrees north and south of equator
characteristics of savannah
- tropical climates in these latitudes is characterised by distinct wet and dry seasons
- fires are common in the dry season, usually ignited by lightning strikes
- herds graze in these areas, along with predators such as lions
distribution/location of rainforests
- cover 6% of earths surface
- found in a broad belt close to equator
- south america, west africa, southeast asia, australia
climate of tropical rainforests
- thrive in equatorial climate
- experience high temps of about 27 degree celsius
- high rainfall of very 2000mm per year
-> climate creates ideal growing conditions and accounts for the lush vegetation growth
plants and animals in tropical rainforests
- rainforests have highest levels of biodiversity in the world
- birds live in the canopy, feeding on seeds + nectar from flowering plants
- mammals, such as sloths + monkeys, are well-adapted to life in the trees
- snakes use trunks of trees as vertical highways from forest floor to canopy’s above
- animals such as deer + rodent browse on vegetation from forest floor
water in tropical rainforests
- most experience a distinct wet season, with high rainfall
-> during this time there is excess water on the ground, sometimes causing flooding
soils in tropical rainforests
- rainforests soils are not very fertile
- nutrients are concentrated in the upper topsoil and are very quickly taken up by plants as they grow
-> trees and plants have shallow roots to maximise their use of these nutrients - intense leaching removes nutrients from the topsoil + redeposits them further down the
people in tropical rainforests
- traditional tribes living in the rainforest live in harmony with the natural environment, gathering only what they need to survive
- increasingly people are exploiting rainforest for commercial gain
-> this is extremely harmful to the rainforest ecosystem + reduces biodiversity as habitats are destroyed
in the nutrient cycle, why are there few nutrients in the litter store
decomposers thriving in the warm and wet conditions quickly break down dead leaves and branches
in a nutrient cycle what indicates a rapid transfer of nutrients
thick arrows
why is there a rapid transfer of nutrients
the climate conditions
- for example, warm and wet conditions promote chemical weathering
where in a nutrient cycle is the vast majority of nutrients stored
in the biomass (mainly the trees)
what is the soil like in nutrient cycles
- contains few nutrients
-> as only nutrients released by decomposers are quickly absorbed by the trees + plants or leached into the soil by the heavy rainfall
what resources do species compete for in TRFs
- light
- food
- shelter
- nutrients
- space
- water
structure of a rainforest from top to bottom
emergents
canopy
understorey
ground layer
emergents
a small number of trees break through the general level of the forest, reaching heights of over 30m
canopy
continuous, dense tree cover protects the ground from heavy rainfall and reduces the amount of light to areas below
understorey
woody plants and shrubs grow in the humid, calm conditions with limited sunlight
ground layer
largely made up of decomposed material broken down by the hot, humid conditions. this level consists of scattered plants and fungi, used by insects as a source of food
how are lianas adapted to TRF conditions
woody vines which climb up trees to reach sunlight so their leaves can grow in the canopy
how are drip tips adapted to TRF conditions
bend upwards when it rains so their force of rain doesn’t make it snap
how are buttress roots adapted to TRF conditions
spread out over wide areas to absorb more nutrients from the thin soil layer
how are poison dart frogs adapted to TRF conditions
- if they eat poisonous insects, they absorb the toxins in their mucus
- feet have extra-strong suction cups to climb and hold slippery branches
how is the three-toed sloth adapted to TRF conditions
- extra vertebrae to be able to turn their neck 270 degrees to check for predators above/below
- can swim in floods (high rainfall=surface runoff)
- grown green algae in fur to camouflage
how are rainforests interdependent ecosystems
all parts of the TRFs are dependent on each other, for example:
1) the warm and wet climate helps fungi and bacteria on the forest floor to decompose dead plant material rapidly. this makes the surface soil high in nutrients, meaning plants can grow easily
2) plants pass on their nutrients when eaten by animals. the dense vegetation provides lots of food, so animal populations are high. when the animals die, their nutrients are transferred back to the soil, making it richer and encouraging lots of vegetation
socio-economic value of rainforests:
- medicines
- water
- energy from HEP
- wild meat and fish
- native food crops
- building materials
- food
- spices
- timber
- resources
- minerals
- anti-cancer
- indigenous tribes
- employment
-> construction
-> mining
-> tourism
-> farming
environmental value of TRFs
- 20% of world oxygen
- biodiversity
- climate
- evaporation cools air
- water cycle
- absorbs carbon dioxide
- roots bind soil
- 20% of fresh water from amazon basin
what is biodiversity
a measure of how many different species live in an ecosystem
why do rainforests have high biodiversity
they have a constant hot and wet climate - ideal for plant growth
what are threats facing biodiversity
- slash + burn agriculture, creating commercial plantations
- unsustainable timber harvesting
- mining + subsequent pollution of water supplies from toxic metals
- development of roads and settlements
how are humans interfering with TRF ecosystems
- change to one part of the ecosystem can have a knock on effect on the whole ecosystem. eg, deforestation can contribute to climate change
- trees intercept and take up lots of water, and release it back into the atmosphere, providing moisture for further rainfal. reducing tree cover may increase the risk of drought, affecting the plants and animals that live in the rainforest ecosystem
- trees stabilise soil with their roots and provide some nutrients when they drop their leaves. with fewer trees, the soil would have less protection from heavy rainfall, the few nutrients present would wash away more easily and plants would struggle to grow
what’s the case study for TRFs
amazon rainforest
what area does the amazon cover
8 million km^2
what countries does the amazon go through
brazil, peru, colombia, venezuela, ecuador, bolivia, guyana, suriname, french guiana
what % of the amazon is estimated to be deforested by 2030 if the current rate is not decreased
30%
how many hectares of forest from the amazon were lost between 2001 and 2012
almost 18 million hectares
what are the reasons for deforestation in the amazon
- commercial farming
- subsistence farming
- commetcial logging
- other: mineral extraction, energy development, population growth, road building
why is deforestation happening in the amazon due to commercial farming
- forest is cleared to make space for cattle grazing or huge plantations
- cattle ranching is the main cause of deforestation in the amazon - in brazil, there are around 200 million cattle on about 450,000 km^2 of pasture
- soy is another commercially farmed crop - up to 250,000 km^2 of former forest has been used for its production. rice, corn and sugar cane are also grown
why is deforestation happening in the amazon due to subsistence farming
- forest is cleared by small-scale farmers who need land to grow food for themselves and their families
- many indigenous people are subsistence farmers
why is deforestation happening in the amazon due to commercial logging
the amazon is full of valuable hardwood trees such as mahogany, which makes logging extremely tempting to both legal and illegal businesses
why is deforestation happening in the amazon due to mineral extraction
- gold, iron ore and copper are mines and exported to help boost countries development
- explosives are sometimes used to clear earth, and deep pits have to be dug to reach the mineral deposits
why is deforestation happening in the amazon due to energy development
- building hydroelectric dams floods large areas of forests
- the construction of the Balbina dam (near manaus, brazil) flooded 2400 km^2 of rainforest
why is deforestation happening in the amazon due to population growth
population growth and migration in the area is putting pressure on the amazon rainforest, especially as the brazilian gov offers land to poor people from overcrowded cities, eg. many farmers have been settled along the Trans-Amazonian Highway
why is deforestation happening in the amazon due to road building
- the 4000km Trans-Amazonian highway connects the brazilian coast to peru, colombia and ecuador, through the amazon
- new roads built for logging have opened up areas that were previously too hard to get to, destroying and threatening more of the forest
impacts of deforestation - local climate change
- the water cycle is disrupted by deforestation as the loss of trees means less evapotranspiration, so less moisture is returned to the atmosphere, meaning fewer clouds are formed, and making the local climate drier
- recycling water acts as a cooling system, so without this the climate gets warmer
- this is a severe issue as it does not have a quick fix and as it continues happening, the impacts will get more severe
- in the long term the impacts can become more severe, like droughts
impacts of deforestation - soil erosion and fertility
- chopping down trees leaves the thin top soil exposed, which is quickly removed by heavy rainfall
- without the top soil layer it is very hard for any vegetation to grow
- soil erosion also leads to the silting up of river courses, which has an impact on marine ecosystems and increases the risk of flooding
- even if the soil is protected, it quickly loses the fertility it had when it was covered by trees
- even more nutrients are removed when land is used for grazing or crop plantations, so farmers have to abandon the patch on land they had been working on to move onto new pastures, which leads to further forest clearance and soil degradation
- this is a severe issue because it means vegetation can’t grow so it can affect farmers and buyers
- in the long term we could run out of space to grow food, leading to a food shortage
impacts of deforestation - river pollution
- gold mining not only causes deforestation but it also leads to polluted waterways as mercury is used to separate gold, which then seeps into the ground
-this leaking mercury poisons fish, as well as inhabitants of nearby settlements, particularly through contaminated drinking water supplies - rivers are also being polluted by silt from soil erosion
- this is a severe issue as it causes water to become polluted
- in the long term because could get ill due to contaminated water and species of fish could go extinct
impacts of deforestation - decline in indigenous tribes
- indigenous tribes are affected more negatively than any other group as deforestation threatens their homes, food supply and traditional way of life
- in the amazon, indigenous tribes have declined in number from 330 to 240 tribes, as logging, the construction of roads, the creation of ranches, plantations and reservoirs, and the opening of mines have forced them all off their land
- many displaced indigenous tribes end up in towns and cities
- this is a significant issue as they can become unwell from being exposed to external viruses
- in the long term their culture and way of life is lost forever
impacts of deforestation - climate change
- the TRF is significant at a global level as it is often referred to as the lungs of the earth as they absorb large amounts of CO2 and release large amounts of O2
- the canopy is able to absorb CO2 until it is chopped down - once that happens the stores CO2 is released back into the atmosphere
- deforestation is a main contributor to the greenhouse effect and therefore climate change
- fire is often used to clear large areas of the rainforest, which releases CO2
impacts of deforestation - biodiversity loss
- deforestation means a loss of habitat for many animals in the tropical rainforest biome
- this threatens individual species, with them becoming endangered, with the threat of extinction
- current estimates suggest that 137 plant, animal and insect species are lost everyday because of deforestation - that’s 50,000 a year
- this loss of species also means that that many cures for life threatening diseases are also lost
- by 2030 parts of the amazon could have lost 30-45% of their main species
how can rainforests be sustainably managed
- selective logging
- replanting
- ecotourism
- education
- conservation
- reducing debt
- international hardwood agreements
sustainable management - selective logging
- only some trees (like old ones) are felled - most trees remain
- this is less damaging to the forest than clearing a whole area
-> if only a few trees are taken from an area the overall forest structure is kept - the canopy remains and the soil isn’t exposed. this allows the forest to regenerate - the least damaging forms are ‘horse logging’ and ‘helicopter logging’ - dragging felled trees out of the forest using horses or removing them with helicopters instead of huge trucks
sustainable management - replanting
- this is when new trees are planted to replace the ones that are cut down
- it’s important that the types of trees replanted match those that were cut down
- in some countries there are laws to make logging companies replant trees when they clear a forested area
sustainable management - ecotourism
- ecotourism minimises damage to the environment and benefits local people
- only a small number of visitors are allowed into an area at a time and rules are imposed to minimise the environmental impacts (eg. litter is disposed of correctly)
- it provides a source of income for local people (eg. they can act as guides and provide accommodation and transport). it can also raise awareness of conservation issues and bring more money in to protect rainforests
- if local people are employed in tourism, they don’t have to log or farm to make money, meaning fewer trees are cut down
sustainable management - education
- educating the international community about the impacts of deforestation can encourage people to buy products from sustainable sources
- local people may damage the forest (eg. by logging illegally) to overcome their poverty, without realising the long-term effects of their actions
- educating the local people about the impacts of deforestation can help to reduce damage to rainforests
- teaching local people about alternative ways to make money that don’t damage the environment as much, means they wont be dependent on unsustainable options in order to make a living
sustainable management - conservation
- many countries have set up national parks and nature reserves within rainforests
-> in these areas damaging activities, eg. logging are restricted. however a lack of funds can make it difficult to police restrictions - as a result, some countries have set up funds which overseas govs and business can invest in -> the countries get the money in exchange for rainforest conservation
-the money can be used to police restrictions and promote sustainable use of rainforests
sustainable management - reducing debt
- many TRFs are found in LICs which often borrow money from wealthier countries or organisations
- this money must be paid back with interest, so poorer countries log, farm and mine in the rainforests to make money to pay back the debt
- reducing debt means they don’t have to do this and rainforests can be conserved
- debt can be cancelled by countries or organisations, but there’s no guarantee that the repayment money will be spend on conservation
- a better solution is a conservation swap, where part of a countries debt is paid off in exchange for a guarantee that the money will be spend on conservation
sustainable management - international hardwood agreements
- hardwood is a general term for wood from certain tree species (eg. mahogany or teak). the wood tends to be dense and hard, so is often used to make furniture
- high demand for hardwood comes from consumers in richer countries means some of the tropical hardwood trees are becoming increasingly rare as more are cut down
- the are international agreements in place to try prevent illegal logging, and to promote the used of hardwood from sustainably managed forests
