Forests Under Threat Flashcards
Why are forest biomes important on Earth?
They absorb and store huge levels of carbon, release oxygen into the atmosphere and provide habitats for many plants and animals,
however, they are increasingly under threat from human activities
What is a tropical rainforest?
A warm, wet ecosystem located between the tropics with dense vegetation
What is the rainfall like in a tropical rainforest?
Extremely high rainfall, exceeds 2000mm a year
Usually seasonal with a distinct wet season
Low during summer months
What is the temperature like in a tropical rainforest?
Very high (~26-27C)
Temperatures are consistent throughout the year,
This is due to the sun shining directly on the equator throughout the year
What is the soil like in tropical rainforests?
Extremely nutrient deprived and infertile because nutrients are washed and dissolved away very quickly by intense rainfall (leeching), leaving an infertile, iron rich soil (latosol)
How do plants get nutrients in tropical rainforests?
From the layer of decomposing organic matter that sits on top, decomposition is sped up by the hot and humid conditions and decomposers. The products are then quickly absorbed by the roots and put back into the living ecosystem
Describe the nutrient cycling in tropical rainforests
Vegetation and trees grow rapidly and shed leaves continuously as conditions are perfect →
Vegetation decays and decomposes rapidly dues to favourable conditions and decomposers in the system→
Nutrients enter the topsoil, but are either quickly picked back up or leeched away by rain, so do not penetrate deep into the ground→
Shallow roots take up nutrients and use them to grow
What are the 4 layers of the tropical rainforest and where are they found?
Forest floor (0-15m)
Understorey (15-30m)
Canopy (30-45m)
Emergent layer (>45m)
What type of life does each layer of the rainforest support?
Forest floor - rodents, large mammals, decomposers
Understorey - insects, frogs, snakes (away from predators)
Canopy - mammals such as monkeys
Emergent layer - birds and flowers
What are 5 adaptations of plants in the tropical rainforest?
Buttress roots
Drip tips
Flexible stems
Lianas
Epiphytes
What is the purpose of buttress roots?
They are roots above ground, adapted for the waterlogged, nutrient deprived soils.
They ensure tall trees are kept stable without going too far into the soil
Describe the leaf adaptations in tropical rainforests
Drip-tips - allows excess rainwater to quickly drip off the leaf, which ensures plants won’t be too wet (prevents rotting)
Flexible stems - move to find light as the dense canopy blocks light
Describe the adaptations of lianas
Woody vines adapted to the dark lower levels.
Roots that grow in the ground, but their vines go high up and wrap around trees (symbiotic relationship), meaning they have access to nutrients from the soil and sunlight from the canopy
Describe the adaptations of epiphytes
Live on the surface of other plants, receiving their nutrients. Adapted to grow on trees high in the canopy so they can receive more sunlight
, but feed off of the nutrients of their host plant (parasitism)
What are some adaptations of animals in a tropical rainforest?
Poisons and venoms
Physical characteristics
Camouflage
Size
Describe the adaptation of poisons and venoms on animals in a tropical rainforest
Poisons and venoms prevent the animal from being eaten.
Many spiders/ snakes can paralyse and kill other animals. Some sting or bite if threatened.
Some are poisonous to eat
Describe the physical adaptations of animals in a tropical rainforest
Primates have developed long limbs and strong tails to help the swing between branches and avoid predators
Some animals have strong claws to help them climb trees e.g. geckos have special pads that stick to branches
Describe the adaptation of camouflage on animals in a tropical rainforest
Camouflage enables the animal to hide from predators
Describe the size of animals in a tropical rainforest
Smaller - easier to move through dense vegetation
Why do tropical rainforests have high levels of biodiversity?
Rapid rate of nutrient cycling means there are always nutrients readily available to support biodiversity.
Hot and humid climate is favourable
Describe the nutrient cycle of a tropical rainforest
Biomass - very large due to dense, layered vegetation with high biodiversity
Fallout - consistent
Litter - small as decay is so rapid in hot, moist conditions
* majority of nutrients are stored in the topsoil and the rest of the soils are nutrient deprived and heavily leeched
Plant uptake - high
Runoff - continuous throughout the year
What are the nutrient additions in a tropical rainforest?
Precipitation
Chemical weathering due to hot, wet conditions
What are the nutrient removals of a tropical rainforest?
High rainfall, litter washed away
Heavy rainfall washes water-soluble nutrients from the soil (leeching)
What is a taiga forest?
Cold forests located at high latitudes (50-70N)
It is the largest biome on Earth
What is the climate like in a taiga forest?
Highly seasonal, temperatures are constantly below freezing (-40–20C) for 8/9 months.
Very dry winters with ~5/15mm of precipitation monthly, majority falls as snow
Summers are very short, but mildly warm (up to 20C), with more precipitation, helping plant growth
Describe the productivity (how much new plant and animal growth there is)of the taiga forests
Very low, low temperatures, frozen ground and dry weather limits plant growth, so there are no net biomass additions for months during winters, affecting food supply for animals
Describe the biodiversity in taiga forests
Very low - low productivity = reduced food supply, thus only few animals can survive.
Only highly adapted plants can survive which only certain herbivores can eat, affecting the amount of carnivores in the ecosystem.
Many animals migrate in the winter to warmer areas, removing chains of the food web
What are the plant adaptations in taiga forests?
Cone shape - snow can slide off instead of weighing down the tree
Flexible branches - allowing them to bend downwards when snow becomes too heavy
Needle shaped leaves - reduces water loss by lowering surface area. Thick waxy cuticle, retains water and reduces freezing
Seeds stored in cones to protect from weather
Evergreen trees
Wide but shallow roots, stopping them from reaching the frozen subsoil (permafrost)
Describe the animal migration adaptations in taiga forests
Many birds come to taiga forests to eat and breed, but they migrate in winters to avoid harsh temperatures
Describe animal hibernation adaptations in taiga forests
Many animals sleep through the winter, their metabolism slows down, conserving energy until they wake up in spring
Describe physical features of animals in taiga forests
Thick, oily fur to retain heat
Large feet to be stable on icy/ snowy ground
White winter coats for camouflage
Describe the nutrient cycle in taiga forests
Biomass - small due to limited vegetation
Fallout - large due to needles falling off trees
Litter - larger as decay is very slow in cold conditions
Soil - nutrient deprived as decay is limited
Plant uptake - low as there is low biodiversity and plants only grow when water is available
What are the nutrient additions in a taiga forest?
Low precipitation - little nutrients through precipitation
Chemical weathering - slow in cold, dry conditions
What are the nutrient removals in a taiga forest?
Runoff - only washes away litter in spring due to lots of meltwater from thawing snow
Leeching - limited due to limited precipitation
Why is the taiga food web less complex than the trf one?
Taiga has limited producer species adapted to cold and dry conditions, thus limited consumer herbivores, and thus, carnivorous numbers are also low
Why does taiga have little variation in vegetation? (apart from the cold)
Short growing season
What is deforstation?
The permanent, large scale removal of trees
What are some causes of deforestation in tropical rainforests?
Subsistence farming
Commercial farming
Logging
Energy source
Biofuels
Mineral extraction
Energy development
What is subsistence farming?
Farming to provide for oneself or their family
What is the process of subsistence farming?
Farmers usually cut down trees to use as wood or construction materials or to sell and leave the land to dry out, leaving behind shrubbery. This is then purposefully burnt as it quickly clears the land and releases nutrients in the soil.
After a few years of cultivation, the soil becomes infertile, so farmers leave the land to recover and move elsewhere
Slash and burn method is used
How is subsistence farming a threat to rainforests?
More people are moving into rainforests, with not enough land for farming, and have also not been educated on the practice.
Less time is being left before the rainforest is burnt again and permanently altering the ecology.
Poses a risk of wildfires
How is commercial farming a threat to rainforests?
Huge area of land are cleared to make space for plantations.
Can be illegal, without considering environment
Describe the purpose of fuel wood
Used for energy for heating, used as an alternative in communities where gas and electricity are unavailable
Describe the process of logging
Wood is cut down, sold as timber or processed to other products. Popular woods sell for high prices
Describe the process of logging
Wood is cut down, sold as timber or processed to other products. Popular woods sell for high prices
Clear felling is used (all trees in an area are cut down)
How is logging a threat to rainforests?
Habitats are completely destroyed and animals are displaced.
Leaving land bare exposes soil to heavy rainfall and thus increased soil erosion
How is mineral extraction a threat to rainforests?
Large areas of land must be cleared for roads and mines, causing severe environmental degradation, which is unrepairable
How is energy development a threat to rainforests?
HEP is a growing form of energy production in tropical rainforests. They insist huge dams to be built in the forests and causes deforestation as large areas of land need to be flooded to make reservoirs.
If deforestation is a direct threat, what is an indirect threat to tropical rainforests?
Climate change
How is climate change impacting TRFs?
Expected drought (dry floor kills decomposers and alters the nutrient cycle)
Lack of water - streams and rivers dry out, killing aquatic life
Forest fires
Changing flowering and fruiting patterns
What are some causes of deforestation in taiga forests?
Logging
Pulp and paper production
How is paper production a threat to taiga forests?
Majority comes from softwoods grown in taiga forests.
What are some threats to taiga biodiversity?
Acid Precipitation
Pests and Diseases
Forest Fires
How is acid precipitation a threat to taiga biodiversity?
Acid rain weakens trees and damages needles, while reacting with soils to produce harmful compounds
How are pests and diseases a threat to taiga biodiversity?
They kill large amounts of trees which disrupts the already delicate food chain. They are usually killed off in the cold winters
