BIODIVERSITY UNDER THREAT Learning Intentions To understand the factors that affect processes in an ecosystem Examine the processes in ecosystems and the factors that affect these We have looked at threats which are occurring on a global scale BUT what threats can you think of that are occur ID: 268973
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Slide1
What might disrupt ecosystem processes?
BIODIVERSITY UNDER THREAT
Learning Intentions:
To understand the factors that affect processes in an ecosystem
Examine
the processes in ecosystems and the factors that affect theseSlide2
We have looked at threats which are occurring on a global scale BUT what threats can you think of that are occurring on a local level?
What about the local?Slide3
Local threats
In small scale areas, local threats can be numerous and represent a severe threat to ecosystems and biodiversity.
Localised deforestation; clearance for farming and urbanisation
Tourism development; trampling, erosion; urbanisation and associated pollution; increased risk of wildfires
Overfishing and harmful forms of fishing e.g. dynamite and cyanide
Siltation from runoff; increased risk of alien invasive species
Runoff from farms and urban areas; eutrophication and heavy metals in rivers, lakes and seas
Mining, ranching and overgrazing, road building leading to ecosystem fragmentation Slide4
What are energy flows?
Energy Flows – primary producers (green plants) at trophic level 1 convert sunlight into energy by photosynthesis
A food chain, or web exists between the trophic levels.
Teritary
level is usually the point at which people harvest or catch them.
50% energy loss at each level from respiration and decaySlide5
What is a nutrient cycle?
Nutrient cycles – the circulation of chemical elements from the environment to organisms and back again into the environment
What three parts does a nutrient cycle have?
What movement can occur between these parts?Slide6
What is a nutrient cycle?
Functioning ecosystems have a continual flow of nutrients and energy through them
These systems are self-regulating, but prone to human disruption:
Deforestation or over fishing depletes the biomass store in the nutrient cycle
Climate change may affect precipitation, runoff, decay rate and weathering rate
Alien species can disrupt the food web, changing the balance of predators and prey
Eutrophication drastically increases available nutrients Slide7
As the world becomes more global more species are moved around the world
This poses a huge threat to ecosystems
Why is there movement?
Alien or exotic species may become established at any trophic level in the ecosystem
What features do these species share in order to survive in an alien environment?
What is the global movement of a species?Slide8
Alien invasive species
Our globalised world has increased the threat from alien invasive species
These are species which move out of their natural habitat and colonise new areas, as a result of human activity
Such species don’t move because they want to find a better place to live!
Some aliens are introduced deliberately, perhaps as a food source, predator or ornamental species, but then escape into the wild and have unintended consequences
Other aliens are accidental introductions
Successful invaders tend to be:
Capable of rapid reproduction
Able to disperse
Rapid growing
Tolerate a range of environmental conditions
Able to eat a wide range of foodsSlide9
Which alien species can you think of?Were these introduced on purpose or by accident?What do you already know?Slide10
Some alien species arrive by ship…e.g. Zebra Mussel which arrived to North America from the Caspian Sea in the ships Ballast water….these eventually ended up in the Great Lakes. In Lake Erie there were 70,000 per m2. and reduced phytoplankton by 80%
What will this eventually lead to?
Air transport introduced snakes to Pacific island of Guam destroyed food chains
Accidental IntroductionsSlide11
Not all introductions are accidental
Introduced species can be difficult to control, they often spread quickly
WHY?
They usually have very harmful impacts
E.g. Pheasants, rainbow trout, Rhododendron
Hedgehogs were introduced to the Outer Hebridies to deal with garden slugs. They have since led to ground nesting birds becoming endangeredSlide12
Study Figure
3
Explain
how human activities have contributed to the condition of
ecosystem goods
and services
. (10)Slide13
Plenary:
Fox hunting is now
banned
what impact has this
had on the British
ecosystem?