living world revision !!

Ecosystems

An ecosystem encompasses all living (biotic) and non-living (abiotic) components in a specific area.

Components of an Ecosystem

  1. Biotic Components: Living organisms, such as plants and animals.
  2. Abiotic Components: Non-living elements, such as soil and climate.

Organisms in Ecosystems

  • Producers: Organisms like grass that use sunlight to produce food.
  • Consumers: Organisms that get energy by eating other organisms. These can be herbivores (e.g., rabbits eating grass) or carnivores (e.g., foxes eating rabbits).
  • Decomposers: Organisms that break down dead material, like fallen leaves or animal remains. Examples include bacteria and fungi.

The Nutrient Cycle

  1. Plants absorb nutrients from the soil to grow.
  2. Animals eat plants, incorporating the nutrients.
  3. When plants and animals die, they decompose, returning nutrients to the soil.
  4. This transfer of nutrients is called nutrient cycling.

Food Chains and Food Webs

  1. A food chain illustrates what eats what (e.g., Blackberry → Sparrow → Sparrowhawk).
  2. A food web shows multiple interconnected food chains, illustrating how they overlap (e.g., Blackberry bush → Greenfly → Ladybird/Spider → Sparrow → Sparrowhawk).

Interdependence in Ecosystems

Each component depends on others for habitat and food. If one part changes, it affects all dependent parts. For example, if blackberry bushes are cut back:

  • Less food for greenfly, leading to a population decline.
  • Reduced food for ladybirds and spiders, also causing their populations to decline.

Global Ecosystems

The climate determines the type of ecosystem that forms. Seven major types include:

  1. Tundra: Located at high latitudes (above 60° N) in Northern Europe, Canada, and Alaska. Characterized by very cold winters, brief summers, little rainfall, mosses, grasses, low shrubs, and permafrost.

  2. Boreal Forest (Taiga): Found between 50-60° N. Has cold, dry winters and mild, moist summers. Dominated by coniferous trees (evergreen with needles).

  3. Grassland: Two types:

    • Savannah: Between the tropics with distinct dry and wet seasons and relatively low rainfall. Dominated by grasses with scattered trees.
    • Temperate: At higher latitudes with more temperature variation and less rainfall. No trees, only grasses.

  4. Temperate Deciduous Forest: Mainly in mid-latitudes with four distinct seasons. Warm summers, mild winters, and year-round rainfall. Deciduous trees lose leaves in winter.

  5. Tropical Rainforest: Around the equator, hot and wet year-round. Lush forest with dense vegetation canopies forming distinct layers.

  6. Hot Desert: Between 15° and 35° north and south of the equator with little rainfall. Hot days and cold nights. Sparse shrubs and cacti in sandy soil.

  7. Polar: Around the north and south poles. Very cold, icy, and dry with a short growing season of about two months.

Tropical Rainforests

Climate Characteristics

  1. Consistent climate year-round without distinct seasons.
  2. High temperatures generally between 20-28 °C, with minimal annual variation.
  3. High rainfall, approximately 2000 mm per year, with daily rain.

Flora Characteristics

  1. Most trees are evergreen to maximize the continual growing season.
  2. Tall trees create dense vegetation cover, limiting light reaching the forest floor.
  3. Many epiphytes, such as orchids and ferns, grow on other plants, obtaining nutrients and moisture from the air.

Soil Conditions

  • Soil fertility is low due to heavy rain washing nutrients away.
  • Surface nutrients are available from decayed leaf fall, but this layer is thin due to rapid decay in warm, moist conditions.

Fauna Diversity

  • Rainforests contain more animal species than any other ecosystem.
  • Diverse fauna includes gorillas, jaguars, anacondas, tree frogs, sloths, and howler monkeys, as well as numerous insects and birds.

Human Adaptation

  • Indigenous people have adapted to rainforest life by hunting, fishing, gathering, and small-scale gardening.

Biodiversity

  1. Biodiversity refers to the variety of organisms in a specific area.
  2. Rainforests have extremely high biodiversity, housing around 50% of the world's plant, animal, and insect species.
  3. Stable climate conditions (consistent heat and moisture) promote high productivity, reducing the need for plants and animals to adapt to changing conditions.
  4. Many organisms have evolved to depend on a few other species and are specific to particular habitats and food sources.
  5. Deforestation and uncontrolled development lead to species extinction and biodiversity loss. For example, threatened species in Brazil increased from 628 in 2008 to 1182 in 2014.

Rainforest Interdependence

All components (climate, water, soils, plants, animals, and people) are interdependent.

  1. Warm and wet climate promotes rapid decomposition by fungi and bacteria, enriching surface soil with nutrients for plant growth.
  2. Plants provide nutrients to animals. Dense vegetation supports large animal populations. Animal waste returns nutrients to the soil.
  3. Symbiotic relationships exist, where species depend on each other for survival.
    • Example 1: Agoutis crack Brazil nut seed pods open. They bury nuts that sprout into seedlings. If agoutis went extinct, Brazil nut tree numbers would decline, affecting other animals and people who rely on them.
    • Example 2: Cecropia trees offer hollow stems and energy-rich food for Azteca ants. The ants protect the trees from predators and competing vines. Without the Azteca ants, Cecropias would be much more vulnerable.

Human Impact on Rainforests

  1. Changes to one part of the rainforest ecosystem can cause knock-on effects.
  2. Deforestation can contribute to climate change.
  3. Trees regulate water cycles by intercepting water and releasing it back into the atmosphere as moisture for rainfall.
  4. Reducing tree cover may increase the risk of drought.
  5. Trees stabilize soil and provide nutrients when leaves drop. Fewer trees lead to soil erosion and reduced plant growth.

Rainforest Adaptations

Plants and animals have adapted to high rainfall, high temperatures, and competition for light.

Plant Adaptations

  1. Trees grow tall to compete for sunlight.
  2. Thick, waxy leaves with pointed drip-tips channel rainwater to encourage runoff, preventing damage and fungal growth. The waxy coating also repels rain.
  3. Climbing plants, like lianas, use tree trunks to reach sunlight.
  4. Smooth, thin bark is common as there is no need for cold protection.
  5. Large buttress roots support tall trees.
  6. Plants drop leaves gradually throughout the year for continuous growth.

Rainforest Layers

  • Emergent Trees: Branches only at the crown for maximum light exposure.
  • Main Canopy
  • Undercanopy: Some plants have large leaves to absorb sunlight.
  • Shrub Layer

Animal Adaptations

  • Strong limbs for movement in the canopy.
  • Short, pointed wings for manoeuvring through dense trees.
  • Suction cups for climbing (e.g., tree frogs) and flaps of skin for gliding (e.g., flying squirrels).
  • Camouflage (e.g., leaf-tailed geckos).
  • Sharp sense of smell for detecting predators in low light.
  • Nocturnal behavior to conserve energy (e.g., sloths).
  • Swimming ability to cross rivers (e.g., jaguars).

Deforestation in the Amazon

Deforestation is the removal of trees from forests.

Scale of Deforestation

The Amazon is the largest rainforest on Earth, covering around 8 million km², including parts of Brazil, Peru, Colombia, Venezuela, Ecuador, Bolivia, Guyana, Suriname, and French Guiana.

  • Nearly 18 million hectares of forest were lost between 2001 and 2012 (average of 1.4 million hectares per year).
  • Increasing since 2012, with deforestation rates in 2021 being the highest since 2006.
  • Estimated that around 40% of the Amazon will be deforested by 2050 if current rates continue.

Reasons for Deforestation

  • Commercial Farming: Clearing land for cattle grazing (major cause in the Amazon, with approximately 200 million cattle on around 450,000 km² of pasture) and soy production (up to 250,000 km²).
  • Subsistence Farming: Small-scale farmers clear forests to grow food for their families.
  • Commercial Logging: Illegal and legal logging of valuable hardwood trees like mahogany.
  • Mineral Extraction: Mining gold, iron ore, and copper.
  • Energy Development: Building hydroelectric dams floods large areas of forest (e.g., Balbina Dam flooded 2400 km² of rainforest).
  • Population Growth: Increased pressure on the rainforest. The Brazilian government offering land to poor people from overcrowded cities, and settling farmers along highways.
  • Road Building: New roads for logging open previously inaccessible areas. The 4000 km Trans-Amazonian Highway connects the Brazilian coast to Peru, Colombia, and Ecuador.
  • Other Causes: 5-10%

Impacts Environmental and Economic

  1. Climate Change:

    • Trees removeCO2 . The Amazon stores around 140 billion tonnes of carbon. Deforestation releases CO2, causing global warming.
    • Brazil's CO2 emissions; up to 75 % come from deforestation. Deforestation is responsible for up to 20% of global CO2 emissions each year.

  2. Soil Erosion:

    • Brazil loses up to 100 tonnes of topsoil per hectare each year due to soil erosion.
    • Loss of tree canopy and roots increase water runoff, reducing soil fertility as nutrients are washed away.
    • Leads farmers to find new areas to farm causing further deforestation.

  3. Economic:

    • Farming in economic development has brought wealth. Brazil exported almost $600 million of beef in March 2018. Brazil is also one of the world's largest exporters of soybeans also increases job opportunity.
    • Mining industry employs lots of population.
    • Logging contributes to economy but can destroy resources the area depends. Timber.
    • Brazilian rubber tappers who extract natural rubber from rubber trees lost their economic welfare.

Shifting Trends in Global Deforestation

  • Deforestation Rate: Very high from 2007 to 2017, with an average of 22 million hectares lost each year.
  • Key Deforestation Locations: From 2001 to 2014, Brazil and Indonesia accounted for almost half of global deforestation.
  • Costa Rica: In 1996, made unauthorised deforestation illegal started paying farmers to restore rainforests. Since then, forest cover has increased to around 60% of land area.
  • Increasing Awareness: Increased global awareness about deforestation has reduced the demand for products from deforested areas (e.g., DivineTM chocolate doesn't use palm oil).
  • Bolsonaro's Impact: Former Brazilian President Bolsonaro had cut the 2021 environment budget by 24% and weakened environmental law enforcement, making it easier to deforest the Amazon.
  • Deforestation rates shot up between 2019 and 2022.
  • Lula's Pledge: In 2023, President Lula pledged to work towards net-zero deforestation in the Amazon by 2030.

Sustainable Management of Tropical Rainforests

Value of Rainforests

  1. Numerous products (rubber, coffee, chocolate, medicines) are sourced from rainforests.
  2. Sustainable development via ecotourism can offer long-term economic benefits.
  3. Protecting forests may reduce the greenhouse effect reducing CO2 emissions and supporting trees absorbing CO2.
  4. Rainforest reduction and destruction result in climate change.
  5. Rainforests also help regulate the climate for drought and flooding.

Sustainable Management Techniques

  • Replanting: New trees are planted to replace those cut down. Matches the trees that were cut. In many countries and logging companies replant trees when they clear forested area.

  • Selective Logging: Only some trees (such as old ones) are felled and most trees remain. Canopy and soil remains therefore more structural benefits are received. Horse logging and helicopter logging: Felled trees are dragged out of forests using horses or removed them with helicopters to preserve overall structure. Helicopters logging and removals are very common from Sarawak, Malaysia

  • Ecotourism: Less people at a time and environmental impacts are being regulated. Disposing waste properly in regulated areas so land and water is disposable. Is there a job tourism offer from which one many can make money. Rainforest alliances teach ecotourism issues in Guatemala community.

  • Education:

    • Community about the impact deforestation has that leads to a rise in people buying things sustainably from the correct sources.
    • Poverty can be overcome damaging the forest in long-term leading to rainforest destruction.
    • Educating damage can help lead to reductions to prevent deforestation.
    • Teaching people on ways to make ways without the cost to the environment will not cause stress to the land or species. Livelihood sustainable education.

  • Conservation: set up national parks and nature reserves within rainforests restrictions are then followed.

    • Can lead to a lack of funds can make it hard to police restrictions.
    • Some funds support restrictions if countries and business and money they get for rainforest conservation fund.
    • Norway Paid 70 million into Brazil rainforests to serve conservation.

  • Reducing Debt

    • Wealthier communities and lower income communities trade and can go in debt into organizations.
    • Reduction funds countries log farm and mine to make money to payback debts to get reduction can lead to them getting debt or cancel and there is no repayment.
    • A swap where part if amount is spent to get guarantee funds conserved.
    • In 2011 USA education debt by 29 million to support for conservation.

  • Hardwood Agreement International:

    • Wood general term for species tree of mahogany or teak. Made by from materials and furniture furniture .
    • High-demand tree can cause people to cut these trees down.
    • Agreements of try to stop illegal logging and using hardwood from forest in a sustainable manner.
    • Consumers can by certified hard wood to prevent cutting tree and deforesting the area to save rainforest ecosystem.