The living world: tropical rainforrests Flashcards
What is the climate like in tropical rainforrests?
They are characterised by warm and wet conditions, characterised by huig levels of rainfall.The temperature is high and constant throughout the year. This is because the powerful Sun is overhead for most of the time.The rainfall is high. This is because the global atmospheric circulation causes an area of low pressure to form at the Equator. The rising air creates clouds and triggers heavy rain.
What are rainforrests characteristics?
-Biodivercity
-tall trees which can grow up to 45m high.
- Varierty of species, often up to 100species in a single hectare
-It supports the largest number of plant and animal species of any biomes
What are the soils of tropical rainforrests like?
The soil is infertile and most of the nutrients is found on the surface where dead leaves decompose rapidly in the hot and humid conditions.
Adaptation of trees for rainforrest confitions: (soil)
- Many trees and plants have shallow roots to absorb these nutrients.
-Sone have fungi growing on the roots transfer nutrients straight from the air.
What is the structure of the forrest?
-Below 5m above ground is the shyrub and ground layer.
- Between 5-15m is the lower canopy trees.
-Between 15-30m is the niddle canopy
-Between 30-60 is the top canopy.
-Epiphytes: they are the pasrasitic plants that take root in trees high in the canopy. They obtain their nutrients from the air rather than the soil.
-Lianas: They are woody plants that take root in the soil but are supported by trees so it can grow upwards to get sunlight.
What are the rates of deforrestation?
Every two seconds an area of rainforest the size of a football field (about one hectare) is being destroyed.
adaptations of plants:
-rapid cycling of nutrients through the ecosystem
- warm humid climate which helps plant growth.
- making the most of the sunligt avalable
-Adapting to the competition for sunlight
-They have drip tip leaves to allow excess water to spill off to prevent leaf damage and mould growth.
- Many trees have wide butress roots and these help stabalise the trees (as their roots are shallow) and increase the surface area for gas exchnage and help the uptake of water.
-Many have straight smooth trunks to reduce the number of ephicytes using the tree as well as to easily allow the water to flow off.
-the emergants which are really fast growing trees which grow right out of the top canopy to get sunlight.
Adaptation of animals:
Due to many species, tehre is competition for food. Some have developed to live off plants and animals that only a few other eat while others developed strong beaks to eat less accesable foods such as nuts.
-Camofage: Some use it to protect themselves from predators, others use it to catch tehir prey
-Some animals have bright colours to warn their predators that they are poisonous and to leave them alone.
(Fun fact: Tribes wipe the ends of their arrows on some frog skin to transfer the deadly poison for hunting.
What is the relationship between animals and plants?
their relationship is very special as some trees depend on animals to help spread their seeds (Animals eat the fruit then travel a distance before the seed pases out their digestive system where the species of plant possbly grows. This helps to maintain teh cycle of food and spreading of the species.
Sometimes, the animals depend on plants for food.
What are the deforrestatio. rates?
they are one of the most endangered ecosystems in teh world. Every 2 seconds, an area the size of a football pitch is being cleared and destroyed. Before: 15.5million km2 but now only 6.2million km2
the faster rates are in brazil and Indonesia who account for 40% of the deforrestation. However the rates in Brzil are decreasing while Indonesia is increasing.
The increasing rates in indonesia and Peru are alarming with indonesias rate doubling teh rate it was between 2005 and 2010 while Peru is almost doubling.
Impacts of deforrestation:
Global impacts:
-Loss of biodivercity (apparently we lose 1 species a day becasue of deforestation. this i9s bad because we are losing genetic resource and potential medicines.
-soil errosion. Trees binds the soil together so with the loss of them it means that teh soil can be washed and blown away much easier.’
Local impacts:
-Global warming: The trees in the canopy help to absorb the CO2 in teh air but this decreases as soon as the trees are cut,. The stored CO2 is also released back into the air due to hoe fire is usually the way people clear forrests.
- Affects the water cycle. With the felling of trees, evaporation is reduced and this means that the amount of moisture returning to the atmosphere decreases and the local climate becomes drier. The water cycle acts as a cooling system so when evaporation decreases, climate gets warmer. The combination of these factors make it ahrd for people and plants to cope as they are not adapted to the scenario.
-decline in indigenous tribes:
Indigenous tribes have lived in a traditional way for many years and they are closely geared to the resources in teh rainforrest. There are only around 240 tribes left compared to the past where tehre were around 330.
many of the tribes have been forced otu of teh rainforrest due to the construction of roads, logging and opening of mines. Most of these people displaced have ended up in towns and cities and only a few have adjusted to this very dofferent environment. Addiction to drugs and alcohol are very common and many ahve died at a young age. This causes the loss of many valuable knowledge such as the medical values of plants.
-Cnflicts between the indigunous tribes and the poeple who are destroying the forrest.
how much estmated does modern meds come from rainforest?
about a quarter
eg. reserpine which is a drug used to treat people with high blood pressure.
What are some positives of deforestation?
-Improving the transportation through the forrest means easier acess to raw materials like minerals and timber. This measn that they can be transported away and sold much easier,
-The logigng of hardwood also paves the way for agriculture. These large scale farms bring money into the country and provides jobs and food fpr the countrys growing population.
-tropicall rainforrests often have mineral deposits including bauxite, iron ore, manganese, gold, siler and diamonds. these can then be exploited and sold and the money earned can then be used to improve hospitals and educations.
Case study: Amazon rainforrest
The amazon caught teh publics attention in 1980s when a series pf shocking news report said that an area of rainforrest the size of Belgium was being cut down.
deforestation ahs continued till present day and in 2005 tehy had already lost 17%of the forrest.
impacts:
global warming
Economic impacts: Brazil is a NEE and it has huge foreign debt as well as lots of poor people to feed so they want to develop the country. Many Brazilians say that deforestation. is a way to develope their country.
What are the causes of deforestation?
percentages:
-Small scale agricuklture: 5%
-cattle ranching: 80%
-Logging: 3%
-Commercial agricuklture: 10%
-Other:2%
1) Subsistence and commercial farming:
the families using subsistence farming clear teh forrest then burn it (slash and burn). they grow crops until the soil is exhausted then move onto a new piece of land.
In1980s and 1990s 43% of teh rainforest was lost and has been replaced by fields for grains and cattle. this allowed Brazil to overtake Austrailia as teh largest exporter of beef in the world.
2) Logging:
this involves cutting down trees for sale as timber or pulp. The timber is used to build homes and furniture and the pulp is used to make paper and paper products.
Logging can be slectove or clear cutting.
-Selective: When loggers chose onlyt the high valued wood such as mahagony
-Clear cutting is not selective and loggers are interested in all typoes of wood so they cut all teh trees down, clearing the forrest
3) Road building:
Roads are an essential way for the Brazillian government to allow developement of the Amazon. The trans Amazonian highway has already opened up large parts of the forrest and this makes peoples acess to the forrest more possible and therefore putting the forrest under threat
4) Mineral extraction: Forrest are cleared to make huge mines and hese can be sold for profit
5) Energy developement:
Focused mainly on Hydro Electric Power. 150 new dam are planed for the Amazon and the power produced is often used for mining. The dams displace many people and the resivour creates the flooding of large areas of land which previously would have been forresrt. A new scheme of the 8000 megawatt Sao Luiz do tapajos dam has been held uop due to the cincerns on the impact on the Munduruku peole.
6) settlement and population growth:
Populations and settlements within the Amazon are growing. many people are migrating to teh forrest for jobs. Settlements like Paraupebas, an iron ore mining town have grown rapidly.