What might disrupt ecosystem processes?

BIODIVERSITY UNDER THREATLearning Intentions:

To understand the factors that affect processes in an ecosystemExamine 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 occurring on a local level?

What about the local?

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

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 decay

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?

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

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?

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 reproductionAble to disperseRapid growing

Tolerate a range of environmental conditions

Able to eat a wide range of foods

Which alien species can you think of?

Were these introduced on purpose or by accident?

What do you already know?

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 Introductions

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 endangered

Study Figure 3Explain how human activities have

contributed to the condition of ecosystem goods and services. (10)

Plenary: Fox hunting is now banned what impact has this had on the British ecosystem?