8 Forests under threat Flashcards
Why is biodiversity in tropical rainforests high?
- Equatorial climate (hot and wet all year round)
- Species have evolved over millions of years
- Multiple layers of vegetation
Examples of adaptations to the climate
- Primates (e.g. monkeys) use their tails for balance and live in the canopy where most food is found
- Bids (e.g. macaws) have strong beaks to break open nuts
- Lianas that uses the tree to climb up to the sunlight in the canopy
- Hardwood trees (e,g, mahogany) have large buttress roots to support the weight of trees and leaves and branches are only found at the top
In the tropical rainforest, why is the nutrient cycle rapid?
- a large biomass store (dense vegetation)
- a small litter store (rapid decay)
- a large take-up of nutrients (rapid plant growth)
- a large supply of nutrients (weathering)
How can the nutrient cycle be distrupted?
By deforestation (which also changes the climate with rising temperatures and more rainfall reaching the ground).
- Litter and soil can be eroded.
- Farming often fails as the rainforest soil contains few nutrients.
Explain the conditions of the taiga
- Climate is harsh
- Biodiversity is low
- Plants and animals have adapted to the cold conditions in order to survive
Explain adaptations of plants and animals in the taiga
- Mammals have thick, oily fur to retain heat
- Some animals hibernate in the winter
- Some birds and animals migrate
- Trees are coniferous: they are cone shaped to allow snow to slip off and the waxy needles reduce water loss
Why is the nutrient cycle in the taiga slower than in rainforests?
- Stores are small, with a smaller flow of nutrients between
- Most nutrients are found in the litter because decay happens much slower in cold temperatures.
- The biomass store is small because trees can only grow for a few months of the year
- Precipitation is lower
What is the main direct threat to tropical rainforests?
Deforestation
Why does deforestation occur?
- Cattle ranching: there is an increasing global demand for beef (and the need to grow soya to feed cattle)
- Poverty: local people cut down trees for subsistence farming and fuelwood
- Debt: countries export timber and grow cash crops to pay off debts
- Development: urbanisation, HEP stations and palm oil plantations
- Demand: the need for timber, oil, gas, iron ore and gold
What is the main indirect threat to tropical rainforests?
Climate change
How does climate change affect tropical rainforests?
- Droughts in the Amazon rainforest are becoming more common
- During droughts, the Amazon can switch from absorbing CO2 to emitting it
- Dry leaf litter reduces decomposition and dying leaves in the canopy reduces food supply, affecting food webs
Where is deforestation greatest?
In countries with taiga forests
What are the causes of taiga deforestation?
- Paper: comes from softwood trees (e.g. fir and pine)
- Construction: softwood is used for construction (for roofs)
- Mining: clearing forest for minerals (e.g. gold and iron ore)
- Fossil fuels: extraction of oil and gas (and tar sands)
- HEP: building dams also destroys taiga
What is the taiga under threat from (which contributes to a loss in biodiversity)
- Forest fires
- Pests and diseases
- Acid rain
How do forest fires occur in the taiga/affect biodiversity?
Hot and dry summers (as Arctic temperature rise) make the forest prone to fires from lightning strikes
How do pests and diseases contribute to a loss of biodiversity?
Warmer temperatures increase insect infection and diseases in coniferous trees
How does acid rain occur/ contribute to a loss of biodiversity?
- Burning of fossil fuels releases sulphur dioxide into the air
- Acid rain weakens trees by reducing photosynthesis and damaging the soil
What are the main global actions to protect rainforests?
- CITES (The Convention on International Trade in Endangered Species)
- REDD (Reducing Emissions from Deforestation and forest Degradation)
What is CITES?
- An international treaty adopted by 180 countries that protects species (e.g. African elephants and the banning of the ivory trade).
- However, protecting species does not prevent deforestation and global warming
What is REDD?
- A UN project that aims to stop deforestation with governments and TNCs funding projects to conserve forests in development countries
- However, it is difficult to police so illegal logging often takes place
Explain the benefits of sustainable management of tropical rainforests
- Ecotourism provides jobs for local people and educates tourists
- Agroforestry maintains biodiversity allowing crops to grow between trees
What is the cost of population growth on tropical rainforests?
Will increase urbanisation and deforestation
Why are there pressures to develop the taiga?
- Oil
- Gas
- Mineral extraction
- HEP
What are ways to protect the taiga?
- Wilderness areas
- National park
- RAMSAR
