CHAPTER 6 Environmental functions of TRFS,how are they used by people, consequences of extraction and how it can be managed sustainably (js study until flashcard 31 since eoy tests only 6.1)

What are the functions of tropical rainforests?

Generation of oxygen

Contribution to carbon storage

Providing habitats for species diversity

Providing protection from soil erosion

How is oxygen generated?

Plants and trees carry out photosynthesis to produce oxygen, in which the trees and plants absorb carbon dioxide, water and sunlight to produce food for their survival and give out oxygen in the process

What is the special trait of oxygen produced in the rainforest?

Trees are evergreen, hence oxygen is produced all year round as the tropical trees can photosynthesise all year round.

What is the special name of forests (with regard to oxygen production?)

Green lungs of the earth.

How do tropical rainforests help the earth?

They help the Earth ‘breathe’

• more than 20% of Earth’s oxygen is generated by the Amazon rainforest

• They absorb carbon dioxide from the atmosphere and release oxygen (photosynthesis)

• They act as the Earth’s natural air purifier as they absorb 2.4 billion tonnes of carbon dioxide in one year.

What are some processes of the oxygen cycle?

Respiration → CO2

Decomposition → CO2

Fossil fuels + fossils → industrial combustion → CO2

Plant respiration → CO2

photosynthesis → O2

Contribution of carbon storage, elaborate

Rainforests and mangroves absorb carbon dioxide from the atmosphere during photosynthesis.

What is this process of storing carbon?

Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide

Elaborate on carbon sequestration

Carbon dioxide in the atmosphere is absorbed by plants and stored within leaves, branches, trunks and roots

Roots of plants also produce soil carbon

As a forest grows, the amount of carbon dioxide that is held within the forest increases → Tropical forests are good carbon storage

The CO₂ held is only released when a plant dies → when a plant decomposes, it is breaks down and CO₂ is released

Mangroves, are they good at storing carbon, and why?

They are effective carbon storers

Soil in mangroves is waterlogged and has few bacteria to break down the carbon stored there.

Additionally, the waterlogged soil contains very little oxygen, which is necessary for decomposition

Thus, materials in waterlogged soil cannot decompose easily, and the carbon continues to be stored and not released into the atmosphere

Carbon storage, tropical rainforests vs mangroves

Mangroves store more carbon than TRFs

How do trees get their mass?

As trees photosynthesis, they form carbohydrates, which make the tree’s biomass

CO₂ is taken in at a certain rate and builds the mass of the tree over time.

What happens when trees die?

Most of its carbon is not released back into the atmosphere as CO₂ , but remains stored in forest soils and wetlands, making forests an essential tool in reducing greenhouse gas emissions from fossil fuels

Whats an exception? (death of trees carbon emissions)

BUT if the trees are harvested and processed into long-lasting wood products (lumber or pulp/paper), the dead tree will keep its stored carbon out of the atmopshere

Explain providing habitats for species diversity

TRFs have warm climate, an abundance of rain and food sources all year round providing a suitable habitat for life

Talk about the diversity and provide statistics

TRFs contain the LARGEST variety of flora and fauna in the world

• More than 1000 species of freshwater fish and birds live in TRFs

• Potentially over 2 million species of insects may be found in TRFs

Why do rainforests have an abundant diversity of flora and fauna?

Ample sunlight to help plants grow and the plants are eaten by animals

The continuous canopy provides the habitat for the plants to grow and animals to live.

Mangroves promote diversity of species by? (fishes)

They provide breeding grounds for young fish, as their dense root networks provide shelter from predators

Mangroves promote diversity of species by? (shrimps and fish fry)

supporting shoals of shrimp and schools of fish fry, as their roots serve as hiding grounds for small aquatic animals, as the spaces between the roots are too small for larger predators

Mangroves promote diversity of species by? (migratory and local birds)

serving as nesting grounds

Why is there an abundant diversity of flora and fauna in the mangroves?

Dead leaves and branches that fall from mangrove plants are broken down by bacteria into tiny particles which fishes, shrimps and crab feed on. These smaller animals are in turn eaten by larger predators such as otters, crocodiles and even tigers.

Why is soil erosion bad?

Soil is needed for plants to grow, but soil erosion causes soil to be removed from the ground

Why is this bad in TRFs?

They receive high amounts of rainfall (ave 2000mm) throughout the year, and when trees are removed, there won’t be natural vegetation to provide cover to prevent surface run-off and hence nutrients in the topsoil will be washed away.

Explain protection from soil erosion (shoot system bio =)

The canopy layer’s leaves, branches and stems of rainforest plants slow down falling raindrops before they reach the ground → allow time for infiltration, less water becomes surface runoff

The raindrops hit the soil with less force and do not cause the soil particles to be detached and washed away by flowing water, resulting in soil erosion

Explain protection from soil erosion (root system)

Roots of rainforest plants help to hold the soil together in place and prevent soil from being washed away easily

More rainwater can infiltrate and percolate into the soil, thus reducing surface run-off.

What happens if the area is not protected by vegetation?

Rain falls directly onto the ground with considerable force, and this causes soil particles to become dislodged or loosened.

The intensity of rainfall that impacts the ground prevents the water from infiltrating or percolating into the ground layer. If the rain falls too quickly, the soil may not be able to absorb all of the rainfall immediately.

This means more water remains on the surface, leading to more surface runoff

The loosened soil particles are easily washed away by the surface runoff

This leads to severe soil erosion.

What are the characteristics of the ecosystem before deforestation?

Many trees offer soil protection from rain erosion

Many leaves fall to the forest floor as litter

Nutrients from litter form a layer of topsoil (humus)

Soil retains water, increasing chemical weathering and the release of minerals from rock

Few nutrients are lost by leaching, leading to very nutritious soil

Nutrient-rich soil promotes rapid vegetation growth.

Effects of deforestation

Very few trees offer protection for the soil

A few leaves dropped as litter

Less nutrient-rich soil is produced (very little humus)

Rapid loss of nutrients by leaching results in acidic soil (ferralitic soil)

A change in composition (mineral content/pH) renders soil infertile

Infertile soil results in very little vegetative growth

What do mangroves do against coastal erosion?

Mangroves protect coastal areas from erosion as they help to reduce the power of strong waves and storms.

How do mangroves protect coastal erosion? (roots)

The dense root systems of mangrove plants help to trap and stabilise loose sediments on the coast so sediments are less likely to be washed away by waves, currents and tides.

How do mangroves protect coastal erosion? (roots, trunks n branches) LAST FLASHCARD TO DO, END OF 6.1!!!

The roots, trunks and branches of mangrove plants cause friction with waves hitting the coast so the waves lose a significant amount of energy, reducing wave erosion

What are TRFs used for?

As a habitat

For raw materials

Recreation purposes

Agriculture

Medicinal cures

Elaborate habitat

About 60 million ppl live in tropical forests

• Yanomami in the Amazon rainforest and the Penan in the rainforest in Sarawak

• Rainforest provides the indigenous people with daily necessities such as food, clothing and medicine.

Examples of indigenous communities living in tropical rainforests

Korowai People

• Live on the island of New Guinea in Indonesia

• They forage for food and materials in rainforests

• They have little contact with cities and urban centres.

Moken people

• Sea nomads who live along the mangrove shores of Southern Myanmar and Thailand

• Hunt for fish in the mangroves and trade the fish for rice and other basic necessities

• Use mangrove wood to construct traditional houseboats or simple huts to live in

Moken people (might not need to study)

• exceptional knowledge of the ocean and marine life. Livelihood is traditionally totally dependent on the resources of the sea, so spear fishing is vitally important to them.

• Unusually good underwater vision because their eyes have adapted to the liquid environment. Even without weights, they are negatively buoyant enough to walk across the bottom of the sea as if hunting on land

…. pg 6

elaborate on what types of raw materials are used by people and what they use it for (wood)

• One of the most valuable products from tropical rainforests is the wood, also known as lumber or timber

• Tropical woods such as mahogany, rosewood and teak are valued for their durability and colour

• People like to use tropical wood for carpentry work and to make other wood-based items

elaborate on what types of raw materials are used by people and what they use it for (ores)

Some places, there are raw materials like copper, diamonds, gold and oil found underneath tropical rainforests

Trees are cut down to explore potential mining areas, and then cleared in huge numbers to exploit whatever mineral has been found. Often explosives are used which is particularly damaging in terms of animal habitats.

For example?

Amazon has lots of gold - around 50 000 hectares of land is being used for gold mining.

The Amazon rainforest is home to the Carajas mine, which is the world’s biggest iron ore mine.

Elaborate recreational purposes

• city dwellers visit TRFs to appreciate and get close to nature

• Spending time in nature is beneficial in reducing stress

• Sights, sounds and smells of a TRF have a calming effect on visitors and improve their well-being

• Activities: Camping, hiking, and birdwatching

Elaborate on agriculture (livestock production)

Farming is also extremely damaging to the rainforest. Huge areas are cleared for cattle ranching, which accounts for around 80% of the destruction in the Amazon rainforest

Mainly to supply higher-income countries with beef (e.g. USA and Canada)

Cattle need large areas to graze, but the quality of pasture declines fairly quickly, meaning farmers have to move their herds onto new areas, which means clearing even more areas.

Elaborate on agriculture (cropping)

Huge areas are also cleared for crop plantations for cash crops like palm oil, soybeans and coffee, which all have vast plantations

Because of over-cultivation, the soil is quickly stripped of nutrients, so farmers then move and search for more land

The demand for sugar cane and biofuel is increasing rapidly, leading to even more destruction.

What else occurs in rainforests? (agriculture farming)

Subsistence farming also takes place, which often uses slash and burn cultivation, where areas of land are burnt to create fertile ash, but these fires can get out of control, causing destruction.

Why are mangroves precious?

Provides wood that is valuable as it is water resistant, which can be used for:

Construction scaffolding

Boats

Jetties

Homes and charcoal

Medicinal cures, elaborate

Some 120 prescription drugs sold worldwide today are derived directly from rainforest plants

According to the U.S. National Cancer Institute, more than 2/3 of all medicines found to have cancer-fighting properties come from rainforest plants

What is deforestation

permanent removal of tropical forests on a large scale

• can happen area but is ,more synonymous with the clearance of tropical rainforests

Why do humans cause deforestation?

Forests are cleared on a large scale to

• Access valuable raw materials beneath the rainforests

• Make way for building cities and homes for a growing world population, especially in developing countries

• Obtain valuable timber

• create land for large-scale agriculture, such as cattle ranches and plantations.

What are some impacts of deforestation?

Loss of diversity

Local climate change

Soil erosion and fertility

River pollution

Decline of indigenous tribes

Elab loss of diversity

• Even if a forest manages to grow back after deforestation, it will lack the biodiversity of the original forest

• Untouched forest is a primary forest. Takes a secondary forest more than 1000 years of continuous growth to be able to return to its original untouched state.

• Many countries lose their biodiversity to the point of extinction, causes big impact on the pharmaceutical industry as possible cure of illnesses disappearing from earth surface.

Why are mangroves experiencing deforestation

Cleared to develop aquaculture so as to satisfy a growing demand for shrimp and fish farms

Converted to residential areas and areas for tourism

Cleared for wood as fuel

Provide construction material

Elab local climate change

• affects climate change on the local and global scale

• 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 this makes the local climate drier.

• Recycling water acts as a cooling system so without this climate → warmer. Drier climate → bad for locals and agriculture

Elab soil erosion and fertility

• Chopping down trees leaves the thin topsoil exposed → quickly removed by heavy rainfall

• Without topsoil, hard for vegetation to grow. Soil erosion leads to silting up of river courses, causing an impact on marine ecosystems and increasing the risk of flooding. Even if soil is protected, it loses the fertility it had when it was covered by trees.

Elab river pollution

Gold mining causes deforestation and pollutes waterways, as mercury used to separate gold seeps into the ground

Leaking mercury poisons fish, as well as the inhabitants of nearby settlements. Rivers are also polluted by silt from soil erosion.

Elab decline of indigenous tribes

Affected as it threatens loss of homes, food supply and traditional way of life

Amazon rainforest’s indigenous tribes declined from 330 to 240 tribes as logging, building roads and ranches, plantations and reservoirs, and opening mines have forced them off their land

Many displaced indigenous people have ended up int own cities, where life is difficult to adjust to as the way of life and environment is so different, and as a result many tribal people end up with alcohol and drug addiction.

What is something that affects other industries due to loss of tribes?

Indigenous people have incredible knowledge about the medicinal value of many rainforest plants - losing these tribes means the knowledge is lost.

What is the enhanced greenhouse effect?

Global warming, increased concentration of greenhouse gases in atmosphere

Greenhouse gases like CO₂, methane and nitrous oxides act as a blanket and trap heat in Earth’s atmosphere

Explain how this works

More concentration of these gases → more heat trapped, temperature of the atmosphere increases

Compare greenhouse effect vs enhanced one

Natural → more heat escapes into space

Enhanced → less heat escapes into space

Why is the greenhouse effect essential?

Maintains surface temp of earth at an average of 15 °C, making it habitable

Explain how deforestation leads to enhanced greenhous effect

Plants help prevent the build-up of carbon dioxide through the process of photosynthesis.

Deforestation removes plants, so less O₂ will be absorbed. Forest fires that occur will add to the accumulation of CO₂ in the greenhouse effect.

how does human activities increase greenhouse gas emissions

Human activities (especially aft Industrial Revolution) such as burning fossil fuels, cattle ranching and deforestation, became the main contributors to the increased amount of greenhouse gases in the atmosphere\

With more greenhouse gases in the atmosphere and fewer plants to absorb CO₂, there is an increase in the amount of heat trapped on Earth

What is global warming

Increase in the mean temperature of the Earth.

• The ten hottest years since records began have been in the last 30 years

• Mean increase in the last 100 years is less than 1dc.

• Seems small, but has devastating consequences on many species in different parts of the world.

Consequences of global warming

1. Melting of polar ice caps

2. Rise of sea levels (can threaten London, New York and Amsterdam)

3. Weather patterns will change with more unusual weather

4. Animals will migrate towards the poles to find habitats with suitable temperatures

5. Tropical diseases may become more common in other regions, like Europe

6. Many species will become extinct.

What methods must countries adopt to approach the problem of sustainable tropical forest usage?

Something that meets the needs of the community

No universal method

What are the most common strategies?

Establishing protected areas

Regulating forestry services

Rehabilitating disturbed areas

Public education

Elab on establish protected areas

• to conserve remaining TRFs

• The objective is to maintain forests as they are and allow flora and fauna to be able to grow undisturbed

• Laws are set up to maintain protected areas

• People who poach and log in protected areas are brought to justice

• Heavy fines or jail terms are common sentences meted out to culprits to ensure that these areas are maintained

Strengths and limitations of protecting areas

Strengths

• Protected areas are useful for educational, recreational and scientific purposes

• Protects indigenous tribes and traditional communities

Limitations

• Protected areas are not fenced → vulnerable to human impact

• Officers protecting areas may accept bribes from illegal logging companies

• A rainforest area may be too large to monitor and protect, but protected areas need to be of a certain size for the flora and fauna to survive.

How did singapore protect its trfs?

Protected 4 areas known as ‘nature reserves’

In total, the nature reserves take up about 34km²

Four nature reserves:

• Bukit Timah Nature Reserve

• Central Catchment Nature Reserve

• Sungei Buloh Wetland Reserve

• Labrador Nature Reserve

The Parks and Trees Act 2005 ensures that the planting, maintenance and conservation of trees and plants in the nature reserves are continued

Elab on controlled logging

Careful management of forests, logging permitted in certain areas only and also carrying it out in a sustainable manner

Put into action to ensure?

• Resources are extracted responsibly

methods of controlled logging:

Small areas are identified to be harvested for wood (1)

Only a small area is logged, so overall damage to the rainforest is reduced (2)

OR

Trees with specific characteristics identified can be harvested (1)

Only trees with specific characteristics are logged, so the overall damage to the rainforest is reduced (2)

Since logged areas are small, the rainforest is able to recover slowly with the availability of sunlight and space for the growth of young trees.

After several decades, the areas can be logged again

How is it carried out?

Allow logging in certain areas only, as well as limiting logging to certain species of trees

Impose penalties on companies which engage in illegal logging

Partner with timber companies to conduct education and research programmes about the damage caused by deforestation

Strengths n limitations

Strengths:

Allows the logged land to regenerate

Limits the destruction of forested lands

Limitations

• Identification of logging permitted species is time-consuming n difficult to enforce

• Flora and Fauna in the forests are still being destroyed in the process

• The time taken for the forest to regenerate is too long

Elab on reforestation

Plant new trees in an area where the original forest was cleared

• Aims to allow flora and fauna to be reintroduced or regenerated through targeted programmes

• During reforestation, a mixture of tree species is planted to mimic the natural vegetation found in the original forest

• Sometimes flora of non-native species is also planted as they are able to take root and grow quickly to limit the impact of soil erosion

How is it carried out?

Often involves non-profit organisations

Takes a long time (15 years) to implement

Strengths n limitations

Strengths:

• Restores biodiversity and allows natural resources to recover

• Improves soil fertility for new plants

• Reduces erosion and flooding in the area

• Maintains water cycles

• Creates new jobs (planting seedlings) for local communities

Limitations

• Depends on availability of native plants for reforestation

• Expensive and time consuming

SG case for this strat

Replanted mangrove forests found on Pulau Semakau

P. Semakau is used as an offshore landfill site

During the construction of the landfill site, efforts were made to reduce the destruction of the mangroves originally found on the island

Despite the conservation efforts, the island still lost 0.14km² of mangroves

The Ministry of Sustainability and Environment has been replanting mangroves by replanting mangrove seedlings

Seedlings have taken root, mangrove forest is recovering

Mangrove replanting: P. Tekong and P. Ubin

Brazil case

In Trombetas, northern Brazil, large tracts of TRFs and soil layers were cleared for mining (previously)

Large tracts of TRFs in Trombetas have been reforested

Seedlings and saplings that were native were grown in a nursery, then reintroduced to abandoned mining sites

Soil layers have been replaced

Many birds and animals returned to the replanted forest but lost 5% of the original species

ELab on pulbic education

Teach the importance and significance of TRFs

About 4.3 billion ppl, or about 56% of the world, live in urban areas. People living there rarely come into direct contact with TRFs

Through Public education, governments and environmental organisations hope more ppl will become aware of the role they play in the destruction of TRFs and take steps to live more sustainable lives

How to achieve a sustainable life?

• Ensure wood products bought come from a sustainable forest

• Recycle paper and products when possible

Strengths and limitations

Strengths:

Once more, people understand the situation, they are more likely to try and make a difference

Public education is a long-term strategy that can have far-reaching effects, as knowledge of the issue is often shared with many people

Limitations

• Takes a long time to materialise

• People are not always receptive to the information

• People may have little or no alternative but to make changes for a more sustainable life.

SG case

Government agencies and non-governmental organisations (NGOs) work to help raise awareness of the importance of TRFs

National Parks Boards regularly organise activities such as talks, exhibitions and workshops to allow people to interact with and learn more about TRFs

Also, put up signage at the four nature reserves to share info about flora and fauna in the area. Allows ppl to take their time to read and process the info

Nature society, an NGO in SG, is active in organising guided walks and tours for nature enthusiasts at Pulau Ubin or the Mandai Mangrove forests