Edexcel Geography

Unit 3: Contested Planet Biodiversity Under Threat

@SHSGeog

The 6 topics of Contested Planet

• The 6 topics in Contested Planet combine into a linked sequence.• This firstly explores resources, then the differences between rich

and poor. • Finally a range of solutions to global problems and inequalities are

examined in ‘Technological Fix’. This last topic is summative and would benefit from being taught last.

Exam Unit 3

• Summer 2015

• Two and a half hours.

• Section A: – Five topics from the six studied. Answer two

questions, each has a section a and b.

• Section B: – Pre release booklet, 1 question, with three

parts, based on one of the six topics. Answer all three parts

Anagrams

• revitoydiibs• Biodiversity• mesiob• Biomes • roftanires• Rainforest • ticrac• Arctic • emtsysoce• Ecosystems

Biodiversity under threat

How can we define Biodiversity?

Starter: From each photo name the ecosystem

What is an ecosystem?

What is a biome?

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving, physical components of the environment with which the organisms interact, such as air, soil, water, and sunlight. It can be as small as a hedge or as large as a rainforest.

Biomes are climatically and geographically defined similar climatic conditions communities of plants, animals, and soil organisms over normally a large area. E.g. Desert.

Biome or ecosystem?

Defining biodiversity • Biodiversity can be defined in a number

of ways. One of the most common ideas is that it has three dimensions

• Species diversity is the most commonly used definition.

Bio…?

•Biodiversity – the variety of genes, species and ecosystems in an area. •Biosphere – the thin veneer of living material on the planet’s surface•Biome – a global scale ecosystem e.g. tropical forest •Biomass - the total weight of living matter per unit area (dry)

What is Biodiversity?

“The variety among living organisms from all sources including, amongst other, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.”The Convention on Biological Diversity

Biodiversity Key Facts• Since the beginning of the century about three-quarters of the world's crop plant varieties

have been lost, and around 50,000 varieties disappear every year.• The world's population obtains about 90% of its calories from 20 crop species.• Tropical forests and woodlands contain at least 50% of all known plant and animal

species.• Some 40% of the world's market economy is based on biological products and processes.• At least 7,000 medical compounds in Western pharmacies from aspirin to birth control pills

are drawn from plants, mostly from less economically developed countries.

Why is Biodiversity Important?

Why biodiversity is

important?

Biodiversity supports complex interactions between plants, animals and people

Biodiversity provides essential goods and services, e.g. food, medicines, raw materials

Biodiversity and natural processes are environmental regulators, e.g. flood control, soil erosion, clean air etc.

Biodiversity has aesthetic and spiritual value – quality of live / health is closely linked to the environment

Biodiversity is valuable for recreation, e.g. in the countryside and urban natures areas

Genetic biodiversity can control a agro-ecosystem resistance to pests / diseases

What is biodiversity? (p66 in text book)

Biodiversity

Species diversity

Ecosystem diversity

Genetic diversity

Endemism(Uniqueness)

Disparity

(Different species)

Species Richness (how many species)

Abundance of species

Total no. of species

A. What is genetic diversity?

Range of genes found within a species. The diversity will often determine the degree of resistance to pests and diseases.

In Agribusiness, breeding new varieties of cereals has led to genetic erosion and genetic pollution. This can weaken the plant’s resistance.

What impact could this have in the future on food

security?

B. What is species diversity?

This is the number of different species in a given area. The ideas of ‘species richness’ and resilience to change. Most common ‘definition’ of biodiversity.

Diversity is needed to enable the ecosystem to carry out its functions such as carbon cycling.

What will removal of species from trophic levels have on energy

flows and nutrient cycles?

C. What is ecosystem diversity?

Range of ecosystem found within an area. The diversity will often determine the degree of resistance to pests and diseases. It is partly controlled by physical conditions, e.g. climate. This includes both biotic (plants and animals) and abiotic parts (soils, geology and climate).

Parakets Humans can alter and eliminate ecosystems (e.g. …………….) and this is an obvious threat to ecosystem diversity.

What local ecosystems are under threat here from

humans?

Advantages Disadvantages

Genetic Diversity Genetic variation within species

Helps explain how isolated groups (e.g. Birds) have adapted to new environments.

DNA has to be analysed so needs high level biological skills.

Species Diversity Number of species in given area

Good basic definition.

Size of area can create problems, larger area means more species. Need to compare like for like.

Ecosystems diversityVarity of ecosystems within an area

A more complex measure of interaction of species with environment. Has a wider focus

Where do you place the boundaries? Needs a constant set of criteria to demarcate the area.

What are the different advantages and disadvantages of using these three different categories to help define Biodiversity?

Biodiversity is the sum of all three definitions. Whilst species richness is easy to measure, biodiversity also clearly includes reactions between species and their environments.

Biodiversity hotspots – areas of very high biodiversity values.

Combined area covers only 2.3% of the Earth's land surface. Each hotspot has already lost at least 70% of its natural vegetation. Over 50% of the world’s plant

species and 42% of all terrestrial vertebrate species are endemic to the 34 biodiversity hotspots.

Homework

1. Make notes under title of Processes and factors influencing biodiversity using the handout (p67-68)

2. Highlight the other handout on What factors influence Biodiversity? (p58-60)

You will also get a 10 mark quiz on this at the start of next lesson!