The document discusses factors that lead to loss of biodiversity such as introduced species, natural hazards, agriculture, habitat degradation, pollution, and hunting. It then evaluates characteristics that make species more vulnerable to extinction, such as being habitat specialists, having low reproductive rates, large body size, low population densities, narrow geographic ranges, and small/declining population sizes. The International Union for Conservation of Nature (IUCN) Red List highlights species at higher risk of extinction based on population trends, geographic distribution, habitat quality and other factors.

1. DP Environmental systems and societies Topic 4 Conservation and Biodiversity

2. 4.2 Evaluating biodiversity and vulnerability

4. Factors that lead to loss of biodiversity Loss of Biodiversity Introduced species e.g. Cane Toad Natural hazards Agriculture Habitat degradation Pollution Hunting List as many factors as you can think of that lead to a loss of biodiversity in a range of ecosystems

5. Factors that lead to loss of biodiversity Can drastically upset an ecosystem. Sometimes it works e.g. rubber trees from the Amazon to South-East Asia. Sometimes it is a disaster e.g. cane toads introduced as a biological control in Australia. Can be purposeful or accidental. Loss of Biodiversity Introduced species e.g. Cane Toad Agriculture Habitat degradation Pollution Hunting Over hunting or over harvesting can eradicate a species quickly. Modern agricultural practices reduce diversity with mono cultures, genetic engineering and pesticides. Eg. volcanos, earthquakes, fires, drought etc. Outside the control of humans. Different to environmental disasters e.g. oil spills Natural hazards A major cause of loss of biodiversity is loss of habitat, Occurs due to human activities on both a small and large scale. E.g. clearing land for development. Degrades or destroys habitats. E.g. spraying pesticides - may drift into wild areas. E.g. Run-off of fertilisers may cause eutrophication.

7. Consider the following: - Describe abiotic factors, such as temperature, rainfall and light. - Why are rainforests highly productive? - Describe biotic factors - why are so many ecological niches are found? what ‘layers’ are found? - What % of land mass on Earth do tropical rainforests cover? - What approximate % of all species occur in rainforests? - Why are they referred to as ‘lungs of Earth’? - What are ‘hotspots’? - What is the approximate loss of rainforests and what are some of the reasons? - How long does it take for forest to regenerate? - What are ‘Green Politics’? Discuss the perceived vulnerability of tropical rainforests and their relative value in contributing to global biodiversity.

8. Rainfall is high and temperatures are warm and stable all year. They are very productive because rates of respiration and decomposition are high. They appear to be fertile, however, most nutrients are held in plants not soil or litter. Rainforests are complex ecosystems with many layers: the tops of the tallest trees (emergent layer), the tops of most trees (canopy layer), the next layer is the understory and the lowest layer is the ground. Rainforests cover approximately 6% of the land area of the planet. Approximately 33% the Amazon Basin, 20% in Africa and 20% in Indonesia. The rest is scattered. Over half of all species of plants and animals on Earth occur in this 6%. Tropical Rainforests are ‘lungs of the Earth’ because they produce about 40% of the oxygen animals use. ‘ Hotspots’ are particular areas of rainforest with a high biodiversity e.g. Malaysian rainforests. An average of 1.5 hectares (one football field) is lost every 4 seconds. This is a result of the demand for resources such as timber, beer, bio fuels and more. Nutrient poor soil makes it hard for rainforests to regenerate. In 65 years some aspects will return but a full recovery could take up to 4000 years. It depends on the level of disturbance. ‘ Green Politics’ is a political idea that place an importance on ecological goals. Has gained popularity since 1980s.

10. The geologic time scale and mass extinction

11. The Five (or six?) Mass Extinctions - Discovery Earth. Mass extinction event Time period Inferred cause of extinction from the fossil record. % of genera lost 1 Late Ordovician 2 Late Devonian 3 Late Permian 4 Late Triassic 5 Late Cretaceous 6 Quaternary?

12. Mass extinction event Time period Inferred cause of extinction from the fossil record. % of genera lost 1 Late Ordovician Drop in sea levels as glaciers formed and rising sea levels as they melted. 57 2 Late Devonian Unknown cause - sea level change & climate change? 50 3 Late Permian Comet or asteroid impact. Or, possibly flood volcanism reducing oxygen in the oceans. 83 4 Late Triassic Massive floods of lava in the Atlantic. 48 5 Late Cretaceous Several mile wide asteroid. Or possibly, gradual climate change / flood-like volcanic eruptions. 47 6 Today? Many scientists believe that Earth is currently going a sixth mass extention related to human (biotic) causes - the first not to be caused by abiotic factors. Far greater and faster rate of extinction than past. 25 by 2015 ?

14. What is extinction? Discuss how the following factors might make a species more prone to extinction? Habitat specialists Low reproductive potential A large body Low population densities Narrow geographical range Small population size / declining numbers

15. What is extinction? Discuss how the following factors might make a species more prone to extinction? Habitat specialists - Includes organisms with a specific diet or habitat requirement. - If their specific resource / habitat is put under threat, so are they. E.g. Giant Panda is dependent on bamboo. Low reproductive potential A large body Low population densities Narrow geographical range Small population size / declining numbers

16. What is extinction? Discuss how the following factors might make a species more prone to extinction? A large body - Only about 10% is passed on at each trophic level and the rest is lost to the environment, - Top predators are rare with large ranges, - They need a lot of food, E.g. Lions Low reproductive potential Habitat specialists Low population densities Narrow geographical range Small population size / declining numbers

17. What is extinction? Discuss how the following factors might make a species more prone to extinction? Low reproductive potential - Some species reproduce slowly and infrequently, - this means a population will take a long time to recover. E.g. Penguins produce one egg per year and do not breed until several years old. Large body Habitat specialists Low population densities Narrow geographical range Small population size / declining numbers

18. What is extinction? Discuss how the following factors might make a species more prone to extinction? Small population size/ declining numbers - Will have smaller genetic diversity and is less resilient to change, - inbreeding can occur and further weaken the population E.g. Large predators and extreme specialists Large body Habitat specialists Low population densities Narrow geographical range Low reproductive potential

19. What is extinction? Discuss how the following factors might make a species more prone to extinction? Low population densities - These organisms usually have large territories, - They may only meet others to breed, - If their habitat is fragmented, e.g. because of a highway, they may not find each other. E.g. Sumatran Rhino in SE Asia Large body Habitat specialists Small population size/ declining numbers Narrow geographical range Low reproductive potential

20. What is extinction? Discuss how the following factors might make a species more prone to extinction? Narrow geographical range - If a species only lives in one place and that place is damaged / destroyed, the habitat has gone, E.g. Golden Lion Tamarin. Lives in fragmented habitat in Brazil. Only 1500 left in the wild. Large body Habitat specialists Small population size/ declining numbers Low population densities Low reproductive potential

21. He is the last Galapagos Island Tortoise known to exist. He was found in 1971. The others were killed by sailors for meat.

22. What do these species have in common? They are all on the International Union for the Conservation of Nature (IUCN) ‘RED LIST’ Do research. Answer the following questions: - Who are IUCN? - Why do we need IUCN? - What is the ‘Red List’? The main purpose of the IUCN Red List is to highlight plants and animals facing a higher risk of global extinction than others. A range of factors are used to determine conservation status: - population size - reduction in population size, - numbers of mature individuals, - geographic range and degree of fragmentation, - quality of habitat, - area of occupancy, - probability of extinction.