Topic 8: Forests under Threat Flashcards
What type of ecosystem is a Tropical Rainforest?
Interdependent - biotic and abiotic components are closely related, if one changes, the others are affected too. Eg:
- warm/wet climate means plants grow quickly
- dense leaf cover protects forest floor from wind & heavy rainfall
Describe the structure of Tropical rainforests
Stratified - affects how much sunlight can reach different levels of vegetation
Layers of the Tropical rainforest
______________ 40m
Emergents
______________ 30m
Main canopy
______________ 20m
Undercanopy
______________ 10m
Shrub layer
______________
Features of the Shrub layer
- Nearest to the ground where its quite dark
- Shrubs have large, broad leaves to absorb as much of the available light as they can
Features of the Undercanopy
- Made up of younger trees that are yet to reach their full height
- Can only survive where there are breaks in the canopy to let some light through
Features of the Main canopy
- Continuous layer of trees
- Like emrgents, they only have leaves at the top
- Dense layer of leaves shades the rest of the forest
Features of the Emergents
- Tallest trees, which poke out of the main canopy layer
- They have straight trunks & only have branches & leaves at the top where they can get light
- Also have big, wide roots called buttress roots to support trunks
Other adaptations of plants
- Plants have pointed tips (drip-tips) that channel the water to a point so it runs off, that way the weight of the water doesnt damage the plant, and theres no water for fungi & bacteria to grow in.
- Plants have thick, waxy leaves - waxy coating to repel rain
- Many trees have smooth, thin bark as no need to protect the trunk from cold temperatures - smoothness allows water to run off easily
- Climbing plants, such as lianas, use the tree trunks to climb up to sunlight
How are animals adapted to conditions in Tropical rainforests?
- Some have strong limbs so they can spend all day climbing & leaping from tree to tree
- Some are camouflaged to hide from predators
- Many are nocturnal
- Adapted to low light levels on forest floor (enhanced senses)
3 ways nutrients are stored in the Tropical rainforests
- Living organisms (biomass)
- Dead organic material (litter)
- Soil
Why do nutrients transfer rapidly in Tropical rainforests
- Trees are evergreen, so dead leaves & other material fall all year round
- Warm, moist climate means fungi & bacteria decompose dead organic matter quickly. Nutrients released are soluble and soaked up by soil
- Dense vegetation & rapid plant growth means nutrients are rapidly taken up by plants’ roots
What is biodiversity?
The variety of organisms (biotic & abiotic) living in a particular area
What is the biodiversity like in Tropical rainforests?
Extremely high - they contain 50% of the world’s plant, animal & insect species, & may contain ariund half of all life on Earth
Why do Tropical rainforests have high biodiversity?
- The biome has been around for a very long time without the climate changing very much, so theres been lots of time for plants & animal to evolve to form new species
- Layered structure provides lots of different habitats, plants/animals able to adapt so lots of species develop
- Rainforests are stable environments - hot & wet all year round
- They are very productive due to high rate of nutrient cycling
Why are food webs in Tropical rainforests complex?
- There are so many different types of species so lots of links
- Some animals can be both primary & secondary consumers
Describe how food chains work
Always start with a PRODUCER (producers make their own food using energy from the sun)
–>
Producers eaten by PRIMARY CONSUMERS (eg. bats, insects)
–>
Primary consumers eaten by SECONDARY CONSUMERS (eg. snakes)
–>
Secondary consumers eaten by TERTIARY CONSUMERS (eg. crocodiles, jaguars)
Reasons for deforestation in Tropical rainforests (7)
Local demand for fuel wood - locals cut down trees to use for fuel to cook, etc
Mineral resource - gold, copper, iron ore found in TRF. Mining methods are destructive
HEP - many TRF’s have large rivers, building dams for HEP floods areas behind dams
Commercial hardwood logging - trees are felled to make furniture/construction
Commercial farming - forests cleared for space for cattle grazing or huge plantations
Subsistence farming - forests cleared so farmers can grow food for themselves
Demand for biofuels - fuels made from plants, trees cut down to make space for these plants
Environmental impacts of deforestation
- With no trees to hold soil together, heavy rainfall washes it away (soil erosion) - can lead to landslides & flooding
- Wihout tree canopy to intercept rainfall & tree roots to absorb it, more water reaches soil - reduces soil fertility as nutrients in soil are washed away, out of reach of plants
- Trees remove CO2 from atmosphere. Also, burning trees produces CO2 - adds to greenhouse effect
What are direct threats?
Involves deliberate, explicit actions that cause damage (eg. deforestation)
What are indirect threats?
Factors that dont involve deliberately cutting down trees but still leads to damage to environment. (eg. climate change)
How is climate change a threat to Tropical rainforests?
In some areas, temperature is increasing & rainfall is increasing, which leads to drought:
- plants & animals are adapted to moist conditions, so many species die in dry weather. Frequent or long periods of drought can lead to extinction of some species
- droughts can also lead to forest fires, destroying large areas of forest
Why are deforestation rates rising in some areas?
Poverty - population growth & poverty mean there are many more small-scale subsistence farmers
Foreign debt - there is a huge market for goods from TRFs, so its an easy way for poor countries to make money to pay back debts to richer countries
Economic development - road & rail projects to promote development open up areas of TRF to logging, mining, farming.
Why are some countries reducing deforestation?
Government policies - some governments are investing in ecotourism & pay landowners to reforest areas leading to forest cover increasing
International condemnation - puts pressure on companies by naming & shaming those involved in deforestation
Monitoring systems - systems provide satellite data to track forest loss, meaning authorities can act more quickly to stop illegal logging, etc.
Name 2 global actions that protect Tropical rainforests
- REDD
- CITES
What is REDD?
Reduced Emissions from Deforestation & forest Degradation is a scheme that aims to reward owners in poorer countries for keeping forests instead of cutting them down
Advantages of REDD
- Deals with the cause of climate change as well as direct impacts of deforestation
- Forest is protected so remains a habitat for species - biodiversity is not lost
- Everyone benefits from reducing emissions & its a relatively cheap option for doing so
Disadvantages of REDD
- Deforestation may continue in another area
- Aspects of REDD are not clear, meaning it may be possible to cut down rainforests, but still recieve the rewards if they are replaced with other types of forest
- Preventing activities, eg. agriculture & mining, may affect local communities who depend on income from them
What is CITES?
Convention on International Trade in Endangered Species of Wild Fauna & Flora is an agreement to tightly control trade in wild animals & plants
Advantages of CITES
- The issue is tackled at a global level - trade of endangered species is controlled worldwide
- Encourages sharing of info about wildlife trade between countries, raising awareness of threats to biodiversity
- Helps different sectors work together
Disadvantages of CITES
- Although individual species are protected from poaching, it doesnt protect their habitat - could still go extinct
- Some rules unclear, eg. trade of ivory
- Not all countries are members - some countries even promote trade of materials from endangered species
What is sustainable forest management?
When a forest is used in a way that prevents long-term damage, whilst allowing people to benefit from the resources it provides in the present & future
What techniques are included in sustainable forest management?
- Selective logging (only certain trees removed rather than large areas)
- Replanting (trees that have been removed are replaced)
Economic challenges of sustainable forest management
- The economic benefits of sustainable management are only seen in long-term - affects poorer countries who need income immediately
- Sustainable forestry is usually more expensive, so it can be difficult to persuade private companies to adopt these methods
- Many sustainable forestry schemes are funded by government departments and NGOs. If priorities of these organisations change, funding could stop quickly
Environmental challenges of sustainable forest management
- If trees are replanted, the new forest may not resemble the natural forest. Trees are replaced but entire ecosystem may not be restored
- Trees that are replanted for logging in the future can be very slow growing - companies may chop down natural forest whilst waiting for the new trees to mature
- Even selective logging can damage lots of trees in the process of removing the target trees
Social challenges of sustainable forest managament
- Generally provides fewer jobs for local people than conventional forestry, so many locals wont see the benefits. Some may turn to illegal logging, which is difficult to police
- If population of a forest area increases, deman for wood & land from forest increases. Sustainable forestry is unlikely to provide enough resources to match increasing demand
How is Ecotourism a good alternative for protecting the TRF
- Only a small no. of visitors are allowed into an area at a time. Environmental impacts are minimised such as ensuring waste & litter are disposed of properly to prevent land/water contamination
- Provides source of income for local people. Can also raide awareness of conservation issues & bring in more money for rainforest conservation
- If local people employed, they dont need to log or farm to make money, meaning fewer trees are cut down
How is Sustainable Farming a good alternative for protecting the TRF
Techniques protect the soil socland remains productive - no need to clear new land every few years:
Agro-forestry - trees & crops planted at same time, so that the tree roots bind the soil & leaves protect it from heavy rain
Green manure - plants which add nutrients to soil as they grow planted to maintain soil fertility
Crop rotation - crops are moved between different fields each year with one left empty, so soil has time to recover
What type of ecosystem are Taiga forests?
Interdependent - all parts of taiga forests are dependent on one another. Eg:
- Plants gain nutrients from soil, & provide nutrients to animals that eat them. In turn, animals spread seeds through their dung, helping plants reproduce
- In summer, trees absorb heat from sun & shade the ground below, preventing permafrost from thawing. The permafrost provides water for plants
How are trees adapted to survive in Taiga forests?
- Evergreen (dont drop leaves in particular season), so they can make best use of the available light
- Needles instead of flat leaves - reduces water loss from strong, cold winds as it reduces the SA
- Cone-shaped, meaning heavy winter snowfall can slide off branches without breaking them
How are animals adapted to survive in Taiga forests?
- Many larger mammals (eg. Caribou) are migratory, move long distances through forest to find food
- Many animals are well-insulated against winter cold (eg. Wolves have thick fur)
- Some animals hibernate to conserve energy & survive winter
- Some have white coats in winter to camouflage - helps hide from predators or sneak up on prey
Describe nutrient cycling in Taiga forests
The cold, dry climate means nutrient cycling is much slower in taiga forests than TRFs.
- Despite constant leaf fall, low temperatures means it takes a long time for the litter to be decomposed & added to the soil - so soil isnt very fertile
- The cold climate also means plants grow slowly - rate of transfer of nutrients from soil to plants is low
Describe the biodiversity of Taiga forests
Much lower biodiversity than TRFs. Many areas of forest cintsin only a single type of tree.
Why is the biodiversity of Taiga forests so low?
- The land was much colder & covered by ice until around 15,000yrs ago - species have had little time to adapt to current climate
- The simple structure means there arent many different habitats - so fewer variety of species
- Much les productive than TRFs: plants grow slowly, so theres less biomass, nutrients take a long time to be returned to soil due to the cold
- The growing season is very short - meaning not much food available, so constant struggle for survival
Reasons why Taiga forests are exploited (5)
Logging for softwood - trees cut down to be made into housing, furniture
Fossil fuels - trees cleared to extract gas & oil from ground. Eg. Tar sands: earth containing a thick, black oil which can be processed into fossil fuels found beneath Taiga forests (eg. Canada). Extraction of tar sands involves open pit mining or strip mining, leading to large-scale deforestation.
Pulp & paper production - felled trees are mashed into a pulp & used to make paper
HEP - dams to generate HEP from rivers in Taiga forests flood large areas of land
Exploitation of minerals - many Taiga forests are rich in minerals (eg. gold, copper, iron ore). Trees cut down for mines & access roads
What are 3 causes for loss of biodiversity in Taiga forests?
- Acid precipitation
- Pests & diseases
- Forest fires
How does acid precipitation cause loss of biodiversity in Taiga forests?
Burning fossil fuels releases gases ( such as sulfure dioxide & nitrogen oxides). These dissolve in water in the atmosphere to form acids that are deposited on plants & soils when it rains/snows
- Damages plants’ leaves & makes it harder for them to cope with cold.
- Can make soils too acidic to support growth
- Kills organisms in lakes & streams
How do Pests & diseases cause loss of biodiversity?
- Many pests & diseases are specific to one species. As there is often a single tree species in a particular area in Taiga forests, its easy for the pests & diseases to spread & multiply, causing lots of damage
- Its thought that warming caused by climate change is making it easier for pests & disease-causing pathogens to survive - new pests & diseases are arriving increasinf frequency of attack
How do forest fires cause loss of biodiversity?
Wildfires are a natural part of the ecosystem - allow new growth & regenerate the forest. However, climate change leads to warmer, drier conditions in Taiga forests, increasing frequency of fires
- Can destroy huge areas of trees & may change distribution of species as some species are better at recolonising burnt areas
- May also break up forests into smaller sections, making it hard for migratory animals that need lots of space to find enough food
How can Taiga forests be conserved? (3)
- Creating a Wilderness area
- Creating a National park
- Sustainable forestry
How does creating a Wilderness area conserve Taiga forests?
Creating an area that is undisturbed by human activity that is managed with the aim of protecting landscape
Advantages of creating a Wilderness area for conserving Taiga forests
- Has highest level of protection - most human activity is banned so area is kept as pristine as possible
- Usually covers a large area so large-scale processes can still take place eg. Animal migration
Disadvantages of creating a Wilderness area for conserving Taiga forests
- The large, remote areas are hard to police
- There is economic pressure on governments from logging, mining & energy companies who want to use the resources
- Pressure from companies & tourists to build roads to allow greater access
How does creating a National park conserve Taiga forests?
Creating an area that is mostly in its natural state that is managed to protect biodiversity & promote recreation
Advantages of creating a National park for conserving Taiga forests
- Can protect particular endangered species
- Covers large area
- Unsustainable human acitivity such as logging & mining is not permitted
- Good access for tourists & recreational users
Disadvantages of creating a National park for conserving Taiga forests
- Must take into account the needs of idigenous communities, who may use the land for hunting
- Tourism may be required to pay for conservation, but access roads, infrastructure & pollution from tourists can harm ecosystem
How does Sustainable forestry conserve Taiga forests?
Creating ways of harvesting the timber from forests without damaging it in the long-term
Advantages of Sustainable forestry for conserving Taiga forests
- Limits can be placed on no. of trees felled or size of clear-cut areas to allow forests to regenerate
- Companies may be required to regenerate the area after logging
- Selective logging means some trees remain to become part of the new forest
Disadvantages of Sustainable forestry for conserving Taiga forests
- Some countries struggle to enforce the restrictions eg. Russia, lots of illegal logging takes place
- There may be lack of clear management or info about the ecosystem
- Different groups may not agree with the rules & restrictions eg. Indigenous people, loggers, environmentalists.
Reasons why Taiga forests should be protected
- Taiga forests store lots of carbon - deforestation releases this as CO2 causing global warming
- Some species are only found in Taiga forests. Because they are adapted to the conditions, destruction of the habitat could lead to their extinction
- Many indigenous people depend on the forest for their traditional way of life
Reasons why Taiga forests should be exploited
- Demand for resources is increasing - people need the wood, fuel & minerals it provides
- Forest industries (eg. Logging & mining) provide lots of jobs (eg. Forestry & logging employ 25,000 people in Canada)
- Exploitation of the forest generates lots of wealth for countries involved (eg. Forest industry in Sweden is worth $15 billion each year)
