Biosphere: The living layer of Earth between the lithosphere and atmosphere.
Ecosystem: A community of plants and animals interacting with the non-living environment.
Biome: A large-scale ecosystem (e.g., tropical rainforest).
The UK is in the temperate deciduous rainforest.
Major Biomes
Tundra: Close to poles (60ºN)—covers Northern Russia, Greenland, and Northern Canada.
- The absence of land at the equivalent latitude prevents its presence in the southern hemisphere.
Low temperatures and short sunlight hours in winter limit plant growth. Low precipitation due to sinking air and strong winds requires plants to have tough leaves and grow close to the ground.
- Only big plants (e.g., mosses) grow due to slow evaporation and frozen subsoil.
Taiga (Boreal Forest): Further N (50-70º) in the northern hemisphere, where temperatures are colder, e.g., Norway, Canada, and Russia.
- Less precipitation: The air is sinking.
- Conifer trees have waxy, needle-like leaves and a small surface area to protect from cold but allow photosynthesis in spring.
- Temperate Forest: 40-55º N (e.g., UK + east coast USA), many low-pressure systems creating rainfall all year round.
- 4 seasons followed—animals may migrate/hibernate.
- In winter, there are fewer sunshine hours; photosynthesis slows down. Deciduous trees save energy and protect themselves from cold temps. by dropping leaves in autumn.
Temperate Grasslands: Similar latitudes to temperate forests but more inland (e.g., the USA, Canadian prairies).
- Seasons become more noticeable as they move away from the influence of oceans.
- Grasses thrive in warm, moist summers and adapt to withstand cold, dry winters by slowing their growth rates.
Deserts: Encircle Earth 25º-30º N+S at the descending high-pressure area of the Hadley cell.
- The temperature consistently hovers between 30°C year-round, but there is a significant variation in the daily temperature due to the cool nights. The region also experiences very little rainfall, with only 250 mm occurring annually.
- Plants are scarce and have water-storing features, such as spines instead of leaves and extensive root systems (e.g., cacti).
Tropical Grasslands/Savannah: These areas are characterized by highly seasonal rainfall, which is insufficient for the growth of trees and forests.
- 25º-35º all year round and 500–1000 mm of rain per year, but always with a dry season—shrubs and trees adapt, e.g., baobab.
- Mainly tall grasses, with some drought.
Tropical Rainforest—around the equator (0º).
- There is 200 to 300 mm of rain annually, making it wet year-round at low pressure.
- Hot all year round (>20º - 30º).
- Dense forests with layers of trees, plants, and other vegetation provide light.
The higher the temperature + rainfall (average), the higher the biodiversity in that biome.
- Tropical rainforests = High biodiversity
- Tundra means low biodiversity.
Local Factors Affecting Biome Distribution
Altitude: Temperatures fall 1ºC per 100m and are very exposed to the wind—forest biomes decrease with altitude (e.g., up a mountain), becoming stunted and then replaced with hardier species like grasses. We encounter distinct biome zones at varying heights.
Rock and soil type: Rock types vary; some are permeable, and some are impermeable. Soil pH can also vary (neutral, acidic, or alkaline) depending on the rock type, which influences the type of plants growing in the biome. Precipitation and temperature also affect the soil's structure and its fertility.
- Overall, different types of plants grow better in different soils, which affects the biome.
Sandy soil: Pale-coloured with many smaller air gaps; water drains through and is very dry -> plants must have adaptations to drought. Often low in nutrients.
Humus: Dark, organic material that forms in soil when plant and animal matter decays. Rich in nutrients and provides ideal conditions for growth for many plants.
- Areas with rich humus (peat) soils in temperate forest/tropical rainforest biomes exhibit high biodiversity.
Drainage: High temperatures can cause large amounts of water to evaporate from the soil. High precipitation can result in flooding, e.g., Scotland's peat bogs.
Impermeable rocks result in waterlogging because the rain cannot drain away.
- Waterlogging can prevent trees from growing, so forest biomes would form—marshes and peat bogs.
Less tree growth as we go higher—the tree line hits—no more trees as the temperature is too low; bare soils and fewer nutrients mean less good growth conditions.
Ecosystems
- Biotic: The living components of an ecosystem, including both plants and animals.
- Abiotic: Non-living components of an ecosystem. E.g., rocks/sunlight.
- Biodiversity: Variety of biotic components in an ecosystem.
- Processes link all ecosystems and biomes, which are complex systems of interaction between their biotic and abiotic components:
Photosynthesis: Plants fix energy from the sun into carbohydrates, creating new plant growth.
Food webs: Move energy through the system from plants -> herbivores -> carnivores
Nutrient cycling: Plants take up nutrients from the soil through their roots and return them to the soil through decay.
Exchange of gases: O₂ and CO₂ between plants, animals, and the atmosphere.
e.g., Taiga has low biodiversity
Abiotic parts: Long, cold winters, low precipitation, and frozen soils.
Biotic parts: Include only specialist plants that can tolerate poor soils, low light, and cold temperatures. Reduced plant food means fewer animals need to adapt to those abiotic factors.
Humans can affect the equilibrium of the ecosystem's interactions by altering/damaging parts, e.g., cutting down trees quicker than they can grow back.
Biotic and abiotic interactions in an ecosystem
1) Photosynthesis - Sunlight - Plant's carbohydrates.
2) Plants absorb CO₂ and release O₂, whereas animals do the opposite, regulating the atmosphere.
3) Energy flows along the food web; after carnivores, it goes to decomposers/detritivores that consume dead plants/animals.
4) Water moves through the soil, plants, and animals and then back into the atmosphere through respiration and evaporation.
- Plants regulate hydrological systems—intercepting rainfall and reducing surface run-off. Plants can also be stores of water, e.g., cacti.
5) The decomposition of plants and animals returns nutrients to the soil. All ecosystems store nutrients in their soil, litter, and biomass.
- These are transferred between stores, but the size of stores and transfer rates vary depending on the ecosystem.
- Biomes store carbon as biomass, which includes leaves, trunks, and animal tissue. When these organisms die, they release their carbon into the soil, which can eventually transform into coal or oil.
6) Weathering, like biological processes, can break down rocks.
- The process of bio-physical weathering occurs when tree roots physically push rocks apart.
- Biochemical weathering occurs when plant and animal acids dissolve the rock, particularly limestone.
- Weathering rocks also provide soil nutrients like magnesium and phosphates.
Tropical Rainforests
- The region experiences both a wet and a dry season.
- The vegetation cover adapts to maximize the benefits of the climate and poor soils.
1) Plants compete for light, which results in a vertical structure of four layers.
2) Access to water issues: A thick canopy stops lots of the rain directly reaching the forest floor; water is transformed by waves and stem flow down the trunks.
- There's lots of competition for food due to vast numbers of different species; each layer has its own distinctive animal life.
- There are many indigenous communities; their food, medicines, and clothing come from the forest mainly.
1) Live a sustainable existence: use the land without harming the plants and animals.
Stratified Layers
- Rainforest is stratified as plants try to take advantage of space and light available.
1) Hot/wet/tropical climate is ideal for the growth of tropical forests with high biodiversity; complex stratification ensures a wide range of ecological niches.
- Overall, plants compete for sunlight, nutrients, space, and water.
Tropical Rainforest Layers Epiphytes: Plant version of a parasite.
Layers: Ground layer, shrub layer/understory, canopy layer, and emergent layer.
Ground Layer:
- The forest floor is damp, attracting shade-loving ferns with large leaves and mammals like jaguars.
- The soil lacks nutrients due to the rapid nutrient cycle; plants quickly absorb and utilise these nutrients, storing the majority in biomass.
Understory/Shrub Layer:
The area is home to young trees with large leaves that capture sunlight, attracting a multitude of insects.
Canopy Layer:
- Home to trees, birds, snakes, tree frogs, etc., as there's so much food available.
- It's a very dense layer and has a few gaps for sunlight to pass by.
- The under-canopy is where most competition takes place, so epiphytes grow on plants they believe will grow well so they can reach the top and grow high.
- Trees defend against epiphytes by having no low-lying branches; branches are straight and have smooth bark.
Emergent Layer:
- Hardwood and evergreen trees, which have broken through the dense canopy layer to reach sunlight, are home to monkeys and birds.
- Benefits of reaching the canopy/emergent layer: Sunlight, water, and optimal conditions for growth.
- More biodiversity is found in upper layers as everything can survive and thrive in optimal conditions for growth.
Tropical Rainforest Adaptations
Buttress Roots:
- Only the top layer of soil contains concentrated nutrients.
- Trees only need to have shallow roots and have evolved to keep tall, slender trunks anchored upright.
- Trees strive to utilise nutrients to reach greater heights and capture more light. Trees with shallow roots do not receive nutrients from deeper soil layers.
Drip Tips:
- Water runs off leaves quickly.
- The rainforest is already warm and wet, so leaves would decompose faster, and moss and algae would quickly grow over the leaf surface, blocking off light, which the leaves compete for.
Animal Adaptations:
- Camouflage -For instance, the fur of jaguars and tigers, which consists of both light and dark patches, blends in with the shade on the forest floor to facilitate hunting.
- Insects also imitate sticks to evade predators.
- Loud Calls/Beaks - Easier for birds to find a mate in dense canopy and beaks help break open nuts.
- Prehensile tails - E.g., monkeys, along with gripping hands and feet for balance, help them maneuver through the canopy.
- For example, sloths have a low and slow metabolism, and their locked tendons prevent them from releasing their grip on a branch during climbing unless their other hand is also on the same branch.
Most animals and plants compete, but many depend on each other. The loss of some tree cover due to deforestation or fire can impact both water and nutrient cycles, leading to soil erosion, increased leaching of nutrients from soils, and increased flooding. Similarly, a change in one element of the food web would have ripple effects throughout the entire system.
The Biosphere The biomass = Dry mass of any living organism
- Carbon Sink - Natural stores for carbon-containing chemical compounds like CO₂ or methane.
- Nutrient Cycle - Nutrients like nitrogen and phosphorus move between the biomes, litter, and soil as part of a continuous nutrient cycle that keeps plants and soil healthy.
- Carbon Sequestration - removal of CO₂ from the atmosphere and locking it upon biotic material.
- Services - Physical processes within biomes that help to maintain bigger physical systems like the hydrological and atmospheric cycle and system.
- Hydrological cycle = The water cycle
Equilibrium of Ecosystems
- For example, the formation of soil is a mixture of tiny particles of rock, dead plants and animals, air, and water. The type of rock and the climate have an impact on the type of soil formed.
1. The biosphere regulates the balance of CO₂ and O₂ in the atmosphere through the respiration of humans and animals, as well as through photosynthesis.
- Biomes act as a carbon sink by sequestering carbon, primarily in trees.
- Soil is a carbon sink. When a plant dies, its roots retain the carbon, and the soil's microorganisms break down the organic matter. However, sometimes these microorganisms are unable to reach the roots, which results in the accumulation of biomass in the soil.
2. Biomes maintain soil health and fertility; most soils would be infertile without leaf litter that decomposes in warm, moist conditions to produce humus. Fungi and bacteria churn up humus and other dead organic matter, further breaking it down.
- Leaf litter helps maintain soil health: dead leaves on the ground decompose, returning nutrients to the soil.
Nutrient Cycle: (main, basic one only)
- The tropical rainforest ecosystem has a large biomass store and a small nutrient store in soil, but in desert ecosystems, most nutrients are stored in soil because:
1) Leaching: rainforest = lots of rain; nutrients in the water cycle.
2) Warm, moist conditions in rainforests cause dead matter to decompose quickly, and plants competing for nutrients are taken up from the soil quickly.
3) Plants regulate the water cycle.
- They absorb water through roots and prevent surface runoff by slowing down flowing water.
- They return water to the atmosphere by transpiration, which contributes to the formation of rain and clouds.
- Mangrove forests line many coasts in (sub)tropical countries such as India and Bangladesh.
It is a natural defense against coastal flooding.
- Deforestation, illegal mining, and urbanisation (e.g., in the Himalayas) have led to widespread flooding: there's a lack of interception and infiltration, and the slopes' gradient leads to fast surface runoff into already large rivers affected by the monsoon.
- How do water cycles change with or without forests (undisturbed vs. deforested)?
- Without trees, evaporation, transpiration, streamflow, and interception cannot occur.
- Without forest cover, rainwater doesn't soak into the ground as it's saturated but stays at the surface, causing run-off and erosion (e.g., soil creep). This means slopes are less stable, and soil and sediments move into the river, leading to more flooding as banks fill up quickly.
1) Rainwater also moves quickly into rivers, which reduces lag time as there's less interception.
- Forests store water, enabling the addition of more.
Nutrient Cycles
- Size of stores varies in different ecosystems.
- In tropical rainforests, nutrient recycling is rapid.
- Tropical soils can be very thick but nutrient-poor as you go down through soils because rainwater leaches nutrients and minerals out.
- Water is also recycled in tropical rainforests: roots take up water, and rain is intercepted (mainly in the canopy).
- As rainforest heats up during the day, the water evaporates into the atmosphere and forms clouds, which makes next day's rainfall conventional.
Rainforest Nutrient Cycle
- In the tropical rainforest, there's a large biomass store and a small litter store, as the nutrient cycle is very quick, and plants take up litter quickly decomposed (warm and moist) for nutrients (there's a lot of competition).
1) This leads to a significant increase in growth and decay transfers.
2) There is also an increase in precipitation due to the constant rainfall.
Food Webs (reference to page 26)
- High rates of nutrient recycling support a high level of biodiversity and complex food webs of optimal growing conditions in the tropical rainforest.
- Each layer of tropical rainforest structure supports different plant and animal species adapted there, which are connected via complex food webs.
- The primary energy source is sunlight, which plants (producers) absorb and then pass on to the food web.
- Destroying a food web can lead to a reduction in biodiversity.
Example:
Biosphere providing life-supporting goods and services
- Services: Functions of a biome that are difficult to put a value on (e.g., adding O₂ to the atmosphere).
- Indigenous people: Original inhabitants of an area; some still live in traditional tribes, but this number is declining; commercial for-profit and large-scale.
- The biosphere and biome provide people with goods—a wide range of resources. Indigenous people have the most direct relationship with the biome to obtain many resources, e.g., logs to cook, wooden spears for hunting, cotton for clothes and string, food, and wood to build residences.
Overall, it provides medicine, food, building materials, and fuel.
Global Services:
- Cultural services, tourism and science (e.g., medicines).
- Timber for buildings and other uses.
- Genetic and chemical materials.
Local Services:
- Food and fuel/wood.
- Recreation, education, spiritual well-being and happiness.
The process involves purifying water and regulating flow in the hydrological cycle.
- Storing carbon and emitting oxygen - Atmospheric balance.
Coral Reefs:
- Provide revenue for local communities and national and international fishing fleets.
People rely on them for both sustenance and income.
Commercial Exploitation:
The biosphere is often overused for profit, often to the point where it can never regenerate.
- Provides jobs, profit, and income for people and government but destroys many ecosystems in doing so. e.g., carbon stores and one of the biggest threats = Conversion of land into farmland to provide food resources.
- Modern-day technology has reduced dependence on the biosphere but has also led to more exploitation of resources.
- Rapid population growth, industrialisation, and urbanisation = Dramatic increase in demand for water, which diverts sources away from the biosphere to cities and the farming industry, which deprives parts of the biosphere of water.
- Biofuels are commercially exploited—they're an alternative to fossil fuels—huge areas of land are being cleared to grow biofuel crops.
- Means local food and fuel prices increase and Indigenous people struggle.
- Many habitats are destroyed.
- E.g., Mountaintop removal mining to collect coal has destroyed many habitats, created mass air pollution, and polluted water supplies.
- Increasing demand for minerals has major impacts on the biosphere, e.g., Mining.
- TNCs want timber for infrastructure, wood for biofuel, space for farming foods and palm oil, and periwinkle for cancer drugs; the main goal is for profit.
- Indigenous people are moving away as prices rise and resources become less available or TNCs, making it harder for them to survive.
Forest Resources
Note: Because peatland stores a lot of carbon, its destruction or draining releases a significant amount of CO₂.
Commercial Use of Forest Resources:
Energy: Biofuels, fossil fuels, and HEP.
Water: This category includes HEP, drinking water, cooling nuclear power plants, energy generation, and irrigation.
Mineral: Tin ores, gold and silver in rivers, lithium and copper.
Exploitation Threats: (most severe -> least severe)
1) Mining for ores - Large-digging tearing against land and rock, clearing anything in the way. Techniques involve clearing forests, blasting at riverbanks, and using heavy machinery. This can expose previously buried chemicals, which can run off into local waterways, polluting rivers.
- Most severe, as land cannot be restored and removes all biodiversity—Indigenous communities struggle as (water) resources are harmed permanently.
2) Dam building for HEP: Led to widespread forest loss. Large tracts of the rainforest are flooded, displacing indigenous people. Heavy construction and roads created lead to further damage and stress on the rainforest.
- Less severe than (1) because dams can't be stored in inaccessible places as it's hard to transport electricity away.
3) Commercial crops - e.g., palm oil needs rainforest climate and lots of land -> Plantations at the expense of rainforests. Palm oil is becoming more in demand as an export.
4) Logging and use of timber: Large trees are cut down and dragged through the forest, destroying biodiversity. However, logging can be done sustainably and still contribute well to a country's GDP.
5) Slash-and-burn agriculture - A form of agriculture where natural vegetation is cut down and burnt to clear land for cultivation. Ash from fire adds nutrients to the soil. Land/Plot that has been used for 5-6 years, becomes infertile, and the farmer moves to a new plot and repeats. Forest regrows over time and allows for biodiversity to partly remain. Mainly used by indigenous groups.
6) Commercial farming - When deforested areas are used as pastures for grazing cattle or to grow fodder crops (to feed animals). Food is made for populations and export -> Contributes to the GDP of less developed countries.
- The biggest threat to all rainforests is deforestation.
2 main causes = Economic development and population growth -> Increases demand for resources like iron ore, gold, timber, fossil fuels, and energy like HEP.
Degradation Threats: (most severe -> least severe)
1) Mining: Roads built to access mines -> More deforestation encourages more subsistence and commercial farming, and there is more logging too. Since mining is very profitable, there will be more demand for it (for technology) in the future. Mining will continue.
2) Commercial Agriculture: Involves monoculture, which decreases biodiversity and is also a leading cause of deforestation. It will become more popular in the future as the population means there'll be more demand for food.
3) Subsistence Agriculture: Trees are cut down on a small plot of land and then burnt for new crops. The leaching often occurs, so a new plot is cleared as exhausted soil can recover, but population pressures have reduced the time in which plots are reused. This will become less of a threat in the future due to urbanisation.
4) Biofuels (deforestation diesel): Land is cleared to grow crops such as palm oil, which is in high demand to reduce reliance on fossil fuels. It may become less of a threat in the future -> More popular renewable strategies.
5) Commercial Logging: Selling rainforest timber for profit, e.g., for debt repayments, poverty, and corruption (illegal logging)—in some Amazon countries, police/government allow logging in return for money. Increasingly stricter laws can be implemented to prevent commercial logging.
Climate Change:
- Warming temperatures affect the atmospheric systems that bring wet season rainfall to the equator. Higher temperatures cause systems to move towards the equator, which in turn causes rainfall in the rainforest.
Impacts of climate change:
- Rains that nourish rainforest diminish.
- The loss of numerous trees that absorb CO₂ from the atmosphere is a significant concern.
- We are losing biodiversity and genetic information that could lead to the development of new drugs and cures for diseases.
- Dry weather could lead to an increase in wildfires, potentially displacing many indigenous people.
Drought
- Drought: A period that is drier than normal, resulting in a decrease in rainfall.
- This means:
- Plants stop growing -> Decreased biodiversity
- Evaporation > Water -> Animals suffer and die
- Forest fires lead to the burning of leaf litter, which in turn releases more CO₂.
- Decay processes can't happen properly. Fewer nutrients in soil.
- Droughts become more common; the rainforest will suffer permanent damage and die back.
- Carbon sequestration could stop as climate change worsens; rainforest areas could become grassland.
Proposal 30–60% of Amazon becomes Savannah.
Climate change in the future:
- Permanent damage to the rainforest leads to more fires.
- Tropical grasslands replace the rainforest distribution as it contracts toward the equator.
- Rainforest switches from carbon sink to carbon source.
- Biodiversity decreases.
Global Action to Protect the Rainforest
International organisations enter into agreements to safeguard the rainforest, and member countries receive aid and assistance.
CITES:
It is illegal to trade plant and animal species across borders. Countries agree to monitor, catch, and punish people who export/import these goods to stop illegal hunting/poaching.
Advantages:
- Many countries have signed up to cooperate on trade.
- There are many protected species.
- Successful—e.g., ivory trade reduced.
Disadvantages:
- Protects species, not ecosystems—doesn't solve deforestation.
- Global warming could undermine its success.
- Relies on countries setting up and funding policing systems that UCs can't afford.
- Species must be under threat to be on the list; by the time they're on the list, it may be too late.
UN-REDD:
- Aims to reduce emissions from deforestation and forest degradation, conserve and enhance forest carbon stocks, and sustainably manage forests.
- Governments and TNCs fund forest conservation projects in developing countries, which allows them to offset their own carbon emissions.
- Developed countries pay for a brake on deforestation.
Advantages:
- It provides international expertise to develop the best approaches.
- Accessible funding is very appealing.
Disadvantages:
- Despite countries signing up, deforestation continues to occur at a rapid pace.
- It's unclear what constitutes progress for replanting.
- For instance, projects that have replanted deforested areas with oil palm trees have received funding.
UN-REDD is more successful than CITES as it helps deforestation directly and has more positives for people in countries with tropical rainforests.
Deforestation rates are rising in some places, but not in others due to the variation in the enforcement of international agreements and policing.
However, the overall amount of deforestation is in decline because:
- Demand for goods has changed, and prices have crashed.
- TNCs are under pressure from environmental groups; they don't want any negatives associated with their brand.
- Increased government commitment to rainforest protection.
- Large urban population translates into fewer people directly dependent on the rainforest.
- Increasing conservation, like national parks.
- Laws and fines for illegal deforestation.
Sustainable Rainforest Management
- Managing a rainforest so that the way it's used now doesn't use up its resources and will allow future generations to use it in the same way.
Alternative Strategies:
- Selective logging - Felling trees only when they're fully grown and letting younger trees mature.
- Agroforestry - Allowing crops to be grown in carefully controlled cleared areas along with trees that may be harvested for fuel wood and timber.
- Replanting - Recreate the forest cover by collecting the seeds from the remaining primary forest, growing the saplings in nurseries, and then replanting them in deforested areas.
- These 3 strategies are better as they're cheaper and lower the rate of deforestation -> There are better profits as you still get resources.
- Eco-tourism involves educational visits aimed at enhancing people's understanding of nature and cultures, nurturing these understandings, and engaging them in projects that support the area. It allows locals to be employed, leading to economic and social growth, and it doesn't threaten the rainforest.
However, sustainable strategies may not be feasible in the future due to factors such as population growth, the need for more space, urbanisation, and climate change, which may hinder tree growth and necessitate crop adaptation.
Taiga/Boreal Forest
- Trees are coniferous and adapted to cold climates.
- The evergreen tree shape allows snow to fall rather than weighing down their branches, and pine needles prevent snow and wind damage.
Climate:
- Short, wet summers -> Temperature up to 20ºC.
- Snow on the ground for many months leads to long, dry winters with temperatures as low as -20ºC.
- Low precipitation overall -> <20 mm for 5 months a year -> Less chemical weathering.
Humans:
The average population density is very low, ranging from 0 to 25 people per km.
Soil:
- The slow rates of decomposition indicate a low level of nutrients.
- Decomposition is slow in the litter layer and stops in winter due to deep freeze.
Animals:
- Food can be difficult to find, so animals hibernate (e.g., mice).
- There are a few larger herbivorous animals, such as moose and deer.
Plants:
- The growing season spans 4-5 months, with little food available in the winter.
- Biomass is low as plants only grow for 4-5 months/year.
- Many mosses, lichens, and fungi.
Water:
- Lots of freshwater was found.
- Numerous migratory fish reside in the extensive undammed rivers.
- Lots of surface water, plus wetlands.
Animal Adaptations:
- There are fewer animal species, which means there is less food available.
- Many hibernate/migrate in the winter.
Brown Bear:
- Thick fur to keep warm and waterproofing.
- Large feet allow for simple walking over snow.
- Claws dig dens, ready to survive winter in hibernation.
Snowy Owl:
- White to blend in with snow.
- Silent when flying to catch prey.
- Migrate as far south as the UK during winter.
Plant Adaptations:
- Coniferous trees use their cone shape to shed snow.
- Coniferous trees (spruce, pine, and fir) are tall and narrow and form a dense canopy.
- Branches are flexible and bend downwards to shed snow.
- Seeds are protected by woody cones.
- Tree roots are shallow yet wide, supporting the tree while avoiding frozen ground below.
- Only ferns, mosses, and lichens grow on the forest floor as it's dark under the dense canopy.
Compared to the tropical rainforest:
- Tropical rainforests have many layers, and different trees have different heights.
- Taiga is sparser (less competition), the more Northern it is, as there aren't optimal conditions for growth.
Nutrient cycle in Taiga:
- There's less biomass stored.
The litter store is larger, allowing for slower decay. Pine needles from coniferous trees, which decompose slowly, make up the majority of it.
Less weathering, as there's less precipitation.
Net Primary Productivity (NPP): A measure of how much new animal and plant growth is added each year in g/m².
- As the temperatures in Taiga decrease, the following outcomes occur:
- Lower productivity
- Less nutrient cycling
- Less biodiversity
- Simpler food webs
Food webs
The taiga ecosystem is significantly simpler than the tropical rainforests found in the subarctic, and it produces less biodiversity.
Threats to the Taiga
- There is less concern about deforestation in the Taiga than in other regions.
- The tropical rainforest is less biodiverse, resulting in fewer species. The tropical rainforest is situated in South America, a region where countries may lack the resources to cause significant deforestation, in contrast to wealthier countries such as Canada and Russia, where Taiga is present and the rate of deforestation is higher.
- Commercial development, the use of local resources for profit, directly threatens Taiga.
- Logging poses a direct threat because it results in the removal of trees, and the absence of pine needles leads to a decrease in soil nutrients.
- Mining minerals and HEP are indirect threats.
- Side effects such as oil spills, fires, and pulp and paper extraction pose a direct threat to the area.
- Since there are no attempts to replant the trees, illegal logging poses a serious threat.
Indirect Threats:
- Includes pollution of water bodies by chemicals used in the production of wood pulp, strip mining of minerals, oil spills, gas extraction with drilling, and HEP developments as well.
- Oil spills are damaging in Taiga: drainage is poor -> oil isn't washed away and remains in the ecosystem for a long time since decomposition is slow. Oil seeps down into the soil and is taken up by shallow roots of coniferous trees that often kill them.
- Strip mining—used to extract minerals near the Earth's surface. Overlying rock and soil were removed to expose mineral deposits that can be extracted easily and cheaply.
- But creates great scars on the landscape
- Tar Sands (alt. fossil fuel) -> Extracted by deforesting Taiga and then strip mining and steaming out tar; either method destroys the forest and produces toxic waste collected in tailing ponds.
- HEP: Flooding during construction often happens. Roads, dams, and reservoirs can disrupt migration routes. Decomposition of flooded forests in reservoirs can also release toxins, leading to pollution. However, toxins can also infiltrate the food web through fish, eventually reaching local populations.
- Mineral Extraction: Private companies obtain licenses to mine, causing environmental damage and taking land away from local populations whose traditional ways of life are threatened. It can lead to pollution. Mining can lead to water pollution, so it's unsafe to drink and harms aquatic populations. It can also lead to the destruction of farmland and cut wildlife the locals rely on. Noise and landscape change stress out migrating animals too.
Threats to Taiga Summary:
- Direct = Logging, paper and pulp production.
- Indirect = Mineral extraction, mining and HEP.
- Indirect threats are more challenging to manage, whereas direct threats are more manageable, allowing us to plant more trees.
Losses of Biodiversity
Acid Precipitation:
- Burning fossil fuels releases chemicals like SO₂ and NOx into the atmosphere. These react with H₂O + O₂ to form acids and fall as rain.
- Acid damages plants and infiltrates the Taiga's soils, lakes, and ponds. It kills insects, decreasing the number of them available to feed bird populations. Acid also kills soil microbes, prevents nutrients from entering the soil, and weakens plant species, making them less resistant to extreme winters, forest fires, pests, and disease.
Forest Fires:
- Caused by lightning stories and human activity.
- Forest fires adapt taiga; the nutrient-rich ash left after a fire benefits species every 80-100 years.
- However, global warming has increased the frequency of fires, which burn young saplings before they can grow to replace old trees.
Pests and Diseases:
- Tree-damaged fungus and mold species include silkworms, mountain pine beetles, and white pine blister rusts.
- Climate change poses an indirect threat to Taiga, as it can lead to stormier weather, which in turn leads to more lightning, which in turn leads to more forest fires.
Overexploitation in the Taiga
Tourists can easily damage Taiga because they are difficult to control and typically don't come to help protect the environment.
Why is it important to protect the Taiga?
- Plants grow slowly and take a long time to recover from damage.
- Animals and plants are highly specialised—climate change means they'll struggle to adapt.
- Slow decomposition means pollution remains in the ecosystem for decades.
- A disease that affects one tree species could have a significant impact on the entire system, as there are only a few species in Taiga.
- Taiga forests are popular tourist destinations year-round.
Challenges to protecting the Taiga:
- Big businesses with low morals are responsible for illegal deforestation.
- Exploited through fossil fuel extraction and softwood.
- We engage in hunting and recreational activities in protected areas.
National Parks: Protect abiotic and biotic components and seek to attract tourists. National parks typically span over 1000 hectares, enjoy legal protection, and have a budget that includes park rangers to monitor and protect the area.
Sustainable Forestry: Trees are cut down but replanted by native Taiga species, and the whole forest is carefully managed so biodiversity isn't damaged. The method is expensive and needs long-term planning, which requires international organisations' funding.
Clear-cutting: An unsustainable method that logs all the trees in a wide area; erosion is more likely, mosses and lichens on the forest floor are destroyed, and landslides/riverbanks are more easily eroded, making it harder for the forest to naturally regenerate.
- Managing a national park is difficult because taiga species often migrate long distances. It is challenging to monitor and regulate hunting and poaching activities. Much of Taiga contains valuable oil and gas resources that could benefit the country and challenge the government.
Conflicts between Players over the Taiga
Sustainable Forestry:
FOR: Local government brings jobs into remote areas.
The national government boosts national GDP over a prolonged period because the forest can regrow well.
AGAINST: The desire to quickly make large profits motivates TNCs with lower moral standards.
Prices for consumers are rising as the cost of sustainable produce increases.
Mining and Energy Companies:
FOR: The local government not only creates jobs in remote areas but also contributes significantly to wealth. Consumers in Europe contribute to the reduction in the cost of fuel.
AGAINST: Both conservatives and environmentalists recognize the drawbacks of fossil fuels.
Indigenous People:
FOR: TNCs with good morals and tourists who think it's culturally important for them to be able to carry out their way of life that is dependent on the rainforest.
AGAINST: Profit-making groups, such as TNCs with lower moral standards, believe that cultural aspects are not significant.
Tourists:
FOR: Local government brings in FDI and provides more jobs.
AGAINST: National park managers find it challenging to manage tourists.
Mining and energy companies are destroying the land, making tourists reluctant to visit.
Consumers:
FOR: National governments—they're energy secure. Businesses generate revenue from the goods they purchase from Taiga.
AGAINST: Furniture, for example, becomes more expensive for consumers as more and more resources are used to increase sustainable methods.
Global Demand Trends
Relate population change to the DTM in Dew Dynamics.
- Demand for resources (water, food, and energy) increases with the increasing world population.
- The natural environment provides us with more resources than we need to survive, and the rise of people's affluence has led to an increase in resource consumption. Individuals are purchasing and utilising more resources than necessary, thereby escalating the demand for these resources.
- Globally, there has been an increase in food demand, but the most rapid rise has occurred in sub-Saharan Africa due to a lack of contraception, education, and family planning, which has led to more births but fewer deaths as healthcare has improved.
- Globally, water consumption has increased, with the most rapid recent rise occurring in Asia due to the presence of numerous emerging countries with large populations undergoing industrialisation.
- Industrial equipment and the population's basic needs require water for cooling.
- A growing global population necessitates increased energy consumption for transport. Increased urbanisation and industrialisation lead to a greater demand for energy → More energy is needed.
- The newest group of countries expected to grow quickly are Mexico, Indonesia, Turkey, and Nigeria. As they gain more wealth, they spend more (consumerism) → Can access more resources → More resources are needed.
- Urbanisation and industrialisation have led to an increased demand for resources, which has had a direct impact on biomes.
- Emerging countries like China and India have been major users of more resources due to a rise in affluence.
- Europe's population has remained stable, maintaining a replacement rate of two. The birth rate has decreased.
- If the cost of living increases, people may not be able to afford to have more children due to the high cost of contraception and education. However, a well-developed healthcare system ensures a low death rate.
- Asia has experienced the fastest population growth due to its high rate of replaceImproved healthcare has led to a decrease in death rates, and children are surviving—people haven't fully realised they don't need to have as many children.
- Africa's population is also increasing (but at a slower rate than Asia's). Religions often don't believe in contraception; birth rates rise, and healthcare is improving, slowly lowering the death rate.
Increased demand for resources:
Future Global Projections:
- The UN has established a high, low, and medium scenario.
- We need an optimistic scenario (low) to figure out how we'll get there, which drives policy changes.
- Middle scenario = Realistic.
- We require a highly pessimistic scenario to effectively address the issue.
- We don't know what'll happen in the future, so we need possibilities.
Theories on Relationships between Population & Resources.
Pessimistic view:
- Robert Thomas Malthus believed that the human population would grow faster than resources.
- This leads to catastrophic events such as war, famine, and epidemics, causing the population to plummet until it finds equilibrium with the available resources.
- Drought-related civil wars have occurred over resources, but the Green Revolution has increased crop yields and slowed population growth in many countries.
Optimistic view
- Esther Boserup believed that as the population grew to the point where resources were becoming sparse, technology would find ways to increase supply to fit the demand.
- The Green Revolution involves selective breeding, irrigation, and the use of pesticides to improve crop yields. Renewable technologies require fewer fossil fuels. However, we continue to face epidemics and an increase in refugees from war, drought, and other hazards.
- For Boserup's theory to be correct in the future, there needs to be better contraception and family planning, more renewable energy, more medical advancements, better global relations, and increased crop yield.