N4 Biology Unit 3 Life on Earth KA 3.2 Threats to biodiversity

Human effects on ecosystems Learning Intention: Identify and describe how human population growth is affecting biodiversity. Success Criteria: Describe the effects of habitat destruction and give examples Describe how overfishing affects ocean ecosystems. Explain what is meant by intensive agriculture, and how it affects biodiversity. Describe the effects of climate change, acid rain and pollution.

Human population growth Human population has been rising rapidly in the last 200 years.

Human population growth The link below shows what the estimated human population of the planet is today. Can you think of any reasons why the human population has increased so much in the last 200 years? What has improved in the last 200 years which means that people are surviving better? World population odometer

Human population growth Here are some clues. Vaccinations against disease Clean drinking water Better sanitation and sewage treatment Better food availability Better disinfectants More medicines and better healthcare

Human demands on the planet Humans use up the planet’s resources such as water, energy and land. We also pollute the planet with our waste. This effect that humans are having on the planet is called the ecological footprint.

Ecological footprint The more resources you use and the more waste you produce, the bigger your ecological footprint. What could you do to reduce your ecological footprint?

Reducing your ecological footprint Use less energy – turn the heating down or insulate your home better. Don’t waste water – turn off a running tap or spend less time in the shower. Recycle as much waste as you can.

Human effects on biodiversity The increasing human population is putting more demands on the planet. More and more ecosystems are being disrupted or destroyed altogether. Here are some examples of ways in which humans are affecting ecosystems. Biodiversity video clip

Habitat destruction Throughout the world, huge forests are being cut down to provide timber and to create space for farms, houses, factories and roads. These forests are home to many different species, so when the forest goes they have no food or shelter. Cutting down large areas of trees like this is called deforestation. Deforestation video clip Ecosystem management video clip

Overfishing Fish are an important source of food for humans. Some of the main fish we capture and eat are cod, haddock, herring pollock and tuna. Overfishing of some of these has caused their numbers to decline.

Overfishing of Atlantic Cod The graph opposite shows how the numbers of Atlantic cod have seriously declined since the 1970s. There are now laws in place in many countries to prevent overfishing and conserve valuable species. This has helped the cod numbers to start recovering.

Intensive farming In order to feed a large population, it is important that we get the maximum amount of food from an area of land. This has led to intensive farming techniques. This involves using huge farms, and using lots of chemicals to encourage growth of plants (fertilisers) and to kill diseases (pesticides).

Intensive farming – the problems Pesticides kill harmful insect pests, but also kill a lot of useful insects. Pesticides can leak into rivers and harm animals there. Fertilisers make plants grow faster. If fertilisers leak into rivers, they can cause excessive growth of algae, killing other species. This is called eutrophication.

Intensive farming – the problems Intensive farming of animals can lead to overcrowded conditions. This affects the health of the animals, and they often need to be given antibiotics to prevent the spread of disease. These antibiotics can then pass to humans when we eat the animal.

Intensive farming of beef cattle (good) (bad) (expensive)

Pollution and ecosystems Humans produce a lot of waste which needs to be disposed of. This includes rubbish and sewage from our homes, as well as harmful chemicals and gas emissions from factories.

Write you ideas and examples on a post it note

Pollution from our homes Waste in our grey bins goes to landfill sites. This can cause toxic chemicals to leak into the soil and kill animals and plants. Waste water from our house contains soaps and detergents, as well as everything that gets flushed down the toilet! This water must be treated to make it safe to release into rivers. Poorly treated sewage can also cause eutrophication in rivers.

Recycling domestic waste By recycling as much waste as possible, we can avoid damage to the environment. Waste glass, metal, paper and plastic can be remade into new materials. Waste food and garden waste can be used to make compost. Some is also used to produce biogas – an alternative fuel.

Pollution from industry Power stations and factories which burn coal and oil produce acidic gases – sulphur dioxide and nitrogen dioxide. These then dissolve in the water in rain clouds. This then leads to acid rain, often hundreds of kilometres away from the source of pollution. The acid rain can kill trees and other plants. It can also cause death of fish by causing lakes to become acidic.

Pollution causes climate change Other gases released from homes, cars and factories are causing climate change. These gases are causing the earth to slowly heat up – this is called global warming. The gases involved are mainly carbon dioxide and water vapour. These are called the greenhouse gases. By using less energy in our homes, switching off appliances not being used, and using cars less we can help to slow down this climate change.

Effects of climate change on ecosystems and biodiversity Small changes in sea temperatures are affecting delicate ecosystems like coral reefs, which are dying. Melting polar ice caps are reducing the area for polar bears to roam and find food. Rising sea levels are flooding some coastal ecosystems, destroying them. Some parts of the planet are becoming drier, and the animals living there cannot find enough water to survive.

must 1. You must include: Examples of pollution caused by humans and how to reduce pollution. should 2. You should include: Causes of acid rain. Causes of global warming. could 3. You could include: Describe the effects of acid rain and global warming on plants and animals.

Accidental pollution Some industries produce harmful chemicals which need to be safely disposed of. These chemicals sometimes need to be transported to where they will be dumped. If they accidentally leak into the environment, ecosystems can be seriously affected. This will reduce biodiversity in that area. Transporting oil in oil tankers at sea can also affect wildlife if there are any accidental spillages.

Natural effects on biodiversity Learning Intention: Identify and describe how natural disasters can affect biodiversity Investigate issues around conservation of endangered species Success Criteria: Give examples of natural disasters that can affect ecosystems Give examples of endangered species Describe ways of conserving endangered species Explain the importance of conservation of species.

Natural forms of pollution Some natural disasters can have negative effects on biodiversity. Forest fires can start in hot dry countries in the summer months and spread over vast areas, destroying ecosystems. Earthquakes, volcanos, tsunamis and severe storms can also damage plant and animal life.

Endangered species The numbers of many animals on the planet are declining due to overhunting and habitat destruction. Some of these species could soon become extinct. These are called endangered species.

Endangered species

Conservation of endangered species Governments throughout the world have taken steps to protect endangered species by: -passing laws making it illegal to hunt or kill certain animals. -making it illegal to pick or destroy certain plants

Conservation of endangered species -Creating protected areas like wildlife reserves and national parks, where animal and plant numbers are monitored and rangers patrol to ensure that animals are not harmed. -Having captive breeding programmes, where endangered animals are fed well and encouraged to breed, and the young animals are protected from natural predators.

Case study of an endangered species -Choose an endangered animal from the list on the next slide, or come up with your own suggestion for an endangered species. -Create a powerpoint presentation or a word document about the animal. -Include where the animal’s natural habitat is, why the animal is in danger of becoming extinct and what steps are being taken to conserve the species -Make it bright and colourful with lots of pictures.

Case study of an endangered species -Amur Leopard -Black Rhino -Hawksbill Turtle -Javan Rhino -Leatherback Turtle -Mountain Gorilla -South China Tiger -Sumatran Elephant -Sumatran Orangutan -Sumatran Rhino -Sumatran Tiger -Amur Tiger -Asian Elephant