Unit 3.3 Threats to biodiversity Flashcards
Extinction
When a species ceases to exist after the last individual in that species dies, it is a natural process. Eventually all species become extinct
Habitat Destruction
Causes include agricultural expansion, urban development, and mining.
Leads to habitat degradation, fragmentation, and loss, significantly reducing biodiversity
Pollution
Sources include oil spills, emissions, fertilizer runoff, and accumulation of toxic chemicals.
Degrades natural habitats and ecosystems, harming wildlife and plant species.
Invasive Species
Non-native species introduced by human activities can disrupt ecosystems.
Compete with, prey on, or bring diseases to native species, affecting biodiversity balance.
Overharvesting and Hunting
Hunting for food, medicine, and the pet trade can lead to population declines.
Example: Overharvesting of North Atlantic cod led to significant population reduction.
Climate Change
Affects habitats and species distributions, leading to increased extinction rates.
Coral bleaching and sea level rise are direct consequences impacting marine biodiversity.
Coral Bleaching
Caused by rising sea temperatures and acidification.
Threatens the survival of coral reefs, crucial for marine biodiversity.
Deforestation
Slash-and-burn agriculture (tavy) and logging are primary causes.
Results in loss of habitats and species, especially in biodiversity-rich areas like Madagascar.
Bushmeat consumption
Increases due to protein needs and local trade, threatening species like the golden-crowned sifaka.
Affects biodiversity and tourism by reducing populations of unique species.
Illegal Wildlife Trade
Driven by demand for exotic pets, souvenirs, and medicines.
Weak enforcement of CITES agreements exacerbates the threat, leading to overexploitation.
Soil Degradation and Erosion
Caused by unsustainable agricultural practices.
Leads to the loss of fertile land, further exacerbating habitat loss and biodiversity decline.
Human Population Pressure
Increased demand for land, water, and resources, leading to habitat conversion and loss.
Puts pressure on ecosystems, contributing to biodiversity loss.
Conservation Challenges and Strategies
Addressing threats requires international cooperation, effective policy implementation, and community engagement.
Protected areas, habitat restoration, and sustainable resource management are key strategies for conservation.
Red List
The ICUN red list of threatened species
- Established in 1964, the
- Critical indicator of the health of the world’s biodiversity.
- Powerful tool to inform and catalyse action for biodiversity conservation and policy change, critical to protecting the natural resources we need to survive.
Factors to determine the conservation status of a species
- Population size
- Trophic level
- Degree of specialization
- Geographic range and distribution
- Reproductive potential
- Degree of fragmentation
- Quality of habitat
- Valued resources
CASE STUDY Vulnerability of rainforests
- Geographical Location
- Climate Features
- Primary Locations
- Biodiversity and Endemism
- Deforestation Rate
- Causes of Forest Loss
- Soil Nutrient Dynamics
- Empty Forest Syndrome
- Impact on Climate Change
- Conservation Challenges
- Tropical rainforests are exclusively located between the Tropics of Capricorn and Cancer, covering regions 23.5° north and south of the equator.
- These biomes enjoy constant sunlight, minimal seasonal temperature variation, and high rainfall, creating a unique and consistent climate.
- The Amazon Basin houses 30% of the world’s rainforests, Indonesia contains another 20%, with the remaining found in the Congo Basin, encompassing countries like the Democratic Republic of Congo, Gabon, Cameroon, Equatorial Guinea, the Central African Republic, and the Republic of Congo.
- Rainforests are highly diverse, multi-layered ecosystems, hosting over 50% of all Earth’s species, many of which are endemic and not found elsewhere.
- Rainforest coverage has dramatically declined from 15% of Earth’s surface fifty years ago to less than 6% today, with forecasts suggesting possible disappearance within 50 years due to human activities.
- Major factors include agriculture and logging for timber, cattle, palm oil, and soy on a commercial scale, alongside deforestation by subsistence farmers and small groups due to soil nutrient depletion.
- Most nutrients in rainforests are stored in plant biomass rather than the soil, causing abandoned cultivated lands to struggle in regaining their original ecosystem even after thousands of years.
- Uncontrolled hunting for bushmeat and the exotic pet trade has led to the disappearance of large species, leaving behind forests devoid of their once-rich fauna.
- Deforestation contributes to global warming through carbon release, potentially accelerating climate change effects and altering the rainforest climate.
- Efforts to curb biodiversity loss face hurdles due to varying international willingness to participate in conservation, influenced by economic, social, and political factors, especially in LEDCs where resource exploration, sustainable development, and conservation are in conflict.
CASE STUDY 3 Species:
Extinct, threatened and recovered
- Dodo (Raphus cucullatus)
IUCN Conservation Status: Extinct. - Sumatran Orangutan (Pongo abelii)
IUCN Conservation Status: Critically Endangered - Iberian Lynx (Lynx pardinus)
IUCN Conservation Status: Endangered (status improved by intervention).
Dodo (Raphus cucullatus)
IUCN Conservation Status: Extinct.
Location: Native to Mauritius, an island in the Indian Ocean.
Extinction Causes: Overhunting by sailors and the introduction of non-native species.
Significance: Became a symbol of human-induced extinction.
Last Seen: The last widely accepted sighting was in the late 17th century.
Sumatran Orangutan (Pongo abelii)
IUCN Conservation Status: Critically Endangered.
Habitat: Tropical rainforests of Sumatra, Indonesia.
Threats: Habitat loss due to logging, palm oil plantations, and human encroachment.
Population: Estimated less than 14,000 individuals remaining in the wild.
Conservation Efforts: Protected areas and rehabilitation centers for displaced or orphaned orangutans.
Iberian Lynx (Lynx pardinus)
IUCN Conservation Status: Endangered (status improved by intervention).
Habitat: Mediterranean woodland and maquis thicket in Spain and Portugal.
Threats: Habitat destruction, decline in prey (mainly rabbits), and accidental deaths from traps and vehicles.
Conservation Success: Intensive conservation programs, including breeding in captivity and habitat restoration, have helped increase their population.
Current Population: Recovery efforts have led to an increase in the population, with the latest estimates showing over 1,000 individuals in the wild.
CASE STUDY Madagascar
- Slash-and-Burn Agriculture: Also known as ‘tavy’, this practice involves cutting down forests for agricultural fields, leading to significant habitat loss for endemic species.
- Bushmeat: Hunting of endemic wildlife for food, known as bushmeat, including lemurs and other species, is a significant threat to Madagascar’s fauna.
- Pet Trade: Illegal capture of exotic species, especially lemurs, for the pet trade further endangers these unique animals.
Invasive Species - Competition and Disease: Introduced species compete with native species for resources, and in some cases, introduce diseases to which local fauna have no immunity.
- Shifts in Habitat Zones: Climate change is expected to shift habitat zones upward in elevation, leaving lowland species with nowhere to go.
Increased Frequency of Extreme Weather Events: More frequent and severe cyclones can devastate habitats and directly harm wildlife. - Water Pollution: Pollution from mining activities and agricultural runoff into rivers and streams affects both aquatic life and the quality of water available to terrestrial species.
Plastic Pollution: Waste management issues lead to plastic pollution, affecting marine and terrestrial animals. - Soil Erosion: The removal of vegetation for agriculture increases soil erosion, reducing land fertility and affecting water quality.
- Overfishing: Coastal and marine biodiversity is threatened by overfishing and destructive fishing practices.
- Overharvesting of plants and animals for traditional medicine, food, and international trade poses a direct threat to species survival.
