Human impact on the environment This next topic looks at the ways that humans have had an impact on the environment.

Human impact on the environment At the end of this topic you should be able to discuss and explain some of the ways that humans have had an impact on the environment.

Human impact on the environment Think back to the work you have previously completed. In what ways have you learned that humans had an impact on the environment? Habitat destruction Introducing alien species Overharvesting of resources Over use of fertilisers Pollution

Human impact on the environment Many of these are related to supplying the needs of an ever increasing human population. Do you know what the human population is? Do you know how population numbers have changed over time?

Human impact on the environment Human population This table shows how the human population has changed over the last 2,000 years and possible future population numbers. Plot this information as a line graph. What do you notice? How do you explain it? YearPopulation in millions , , , , , , , , ,000

Human impact on the environment

Human population The increasing population requires an ever increasing food yield. Some experts believe that there is enough food to go round but it is not being distributed evenly, others do not. But everyone agrees that food production will need to increase.

Human impact on the environment Human population and food production

Human impact on the environment Food production Is very important. Farming methods have changed in many countries through: Intensive techniques with many monocultures Increasing use of fertilisers Increasing use of pesticides Use of GM crops

Human impact on the environment Fertilisers are used to help with soil fertility. Sometimes farmers can use too much man made fertiliser. What is the impact to the environment of over using fertilisers? What are the alternatives to using too much man made fertiliser? organic farming, natural fertilisers, traditional crop rotation methods

Human impact on the environment Pesticides are used to control pest species of insects. These chemicals are convenient but can accumulate to toxic levels as they are passed along a food chain. This is called bioaccumulation. An example of this includes the use of DDT. Banned in Britain but used in other countries.

Human impact on the environment Bioaccumulation also occurs when pesticides end up in the fresh water ecosystems

Human impact on the environment Genetically modified crops (GM crops) are now being used to: Produce increased yield Produce disease resistant crops Produce drought resistant crops Produce crops that make new chemicals If time you could research GM crops

Human impact on the environment Monocultures This is when farmers grow large areas of the same type of crop (often year after year). This is advantageous because: Large machinery can be used Fertilisers can be applied easily with machines Pesticides can be applied easily with machines Profit margins are maximised Disadvantages are that diseases among the crops spread easily and soil fertility can be reduced.

Human impact on the environment The reintroduction of native species Another way that humans impact on the environment is the reintroduction of native species. An example of this is the European Beaver (Castor fiber) Watch the ‘Countryfile’ clip on this. As you watch make a note of the positive and negative impact the Beavers have on the environment.

Human impact on the environment Write your notes up for the assessment 2.2 and 2.3 ( describe the use of an application of biology and consider the effect of this application on the environment/society) 2.2 Describe an application of Biology. (the reintroduction of native species). 2.3 Describe how the issue effects the environment. (how does the reintroduction of beavers effect the environment)

Human impact on the environment You should be able to discuss and explain some of the ways that humans have had an impact on the environment. Complete the place mat activity to summarise your group ideas.