Biodiversity and the distribution of life on planet earth

Previously we learnt about Niches Collect and complete the find me sheet. You have 5 minutes (or the first person to finish) to get round the class finding someone to sign your sheet if they can explain a word or phrase in a box. Only one person per box The teacher will review it with you by asking around the class and the next slide.

We have been learning about Niches Competition, parasitism and predation. Light, temperature and nutrient availability. A niche is the role that an organism plays within a community. What is a niche? What kind of resources will organisms be using in their ecosystem? What types of interactions occur between organisms in A community?

In this section we are learning more about specific factors affecting biodiversity. Biotic and abiotic factors affect biodiversity in an ecosystem Human activities can have an impact on biodiversity Grazing and predation are biotic factors pH and temperature are abiotic factors At the end of the section you should have an improved understanding of these factors and how they affect biodiversity Natural hazards can have an impact on biodiversity

Biotic factors How would predation and competition affect organisms? (Remember you already discussed this in a previous lesson). How might these affect biodiversity? These are factors that are living including diseases, predation, competition (space, light, nutrients, reproduction) and grazing.

Grazing What is grazing? However too many sheep would over graze the area and reduce biodiversity. The other weaker species get the opportunity to grow more so biodiversity is kept high. How might this help the other plants growing in the area? Sheep are selective grazers. They select the more dominant competitive grasses to eat. It depends on the type of grazer. Animals that eat plants to gain their energy are called grazers. Commonly sheep, deer and rabbits are thought of as grazers. How can these animals affect biodiversity by grazing?

Rabbits are relatively unselective grazers. What does this mean? Obviously a massive population of rabbits overgrazing an area would decrease the biodiversity. The more vigorous plants are kept in check. By eating almost all types of plants on grassland they maintain a high diversity.

Abiotic factors As the temperature increases reactions happen faster, up to a certain point so growth could increase. At lower temperatures there will be slower growth. All organisms rely on enzymes to control chemical reactions. Temperature would affect the growth rate of organisms. Why would temperature affect growth rate? How might these factors affect organisms? How might this affect biodiversity? These are factors that are non living including light, moisture, pH, temperature, O 2 and CO 2.

pH is another factor that can affect organisms especially living in aquatic environments. Why would pH affect organisms in aquatic environments? Organisms work at their best in a small pH range. If the pH changes then the biodiversity may be affected as an organisms chances of survival may be affected. Examples of this include fish and corals growing in aquatic environments.

The affect of human activities on biodiversity How are humans affecting the survival of plants and animals on the planet? If animal and plant numbers decrease, biodiversity decreases. Watch Episode 2 from State of the Planet DVD. Make a note of the 5 ways humans are affecting biodiversity (with examples) as the DVD is playing.

vimeo.com/ Review of Biodiversity and the distribution of life on planet earth Here are 2 short clips to recap some of the work on Biodiversity