Transcript Disruption to Ecosystems

Disruption to Ecosystems
Energy And Nutrients
• Energy and nutrient
flows are fundamental
to an ecosystem
functioning properly
• Nutrient Cycle – the
feedback of minerals
from decomposed
organic material back
into plants
• Energy Flows – the
flow of energy through
the system e.g. food
chain or food web
Energy Flows
• Primary producers at level 1 convert
sunlight into energy via photosynthesis.
• Energy is lost through each respiration at
each stage
• The amount of biomass at each level also
decreases.
• Any change to this cycle can put the
ecosystem under threat.
Nutrient Flows
• The circulation of chemical elements from
the environment to organism and back to
the environment again.
• Nutrients are stored as either soil, litter or
Biomass
• This is easily affected as it is an OPEN
SYSTEM and nutrients can be added
physically or by human elements.
Precipitation
Runoff
Litter
Decay Pathway
Weathering
Fallout Pathway
Soil
Biomass
Uptake Pathway
Leaching
Movement of Species
• As we have traversed the world species
have been moved both knowingly and
unknowingly
• They can pose a threat to the native
ecosystem
• Along with that many species become
invasive along with other problems
Alien Species share several features
• Enhanced survival rates
• Lack native predator
• Not as susceptible to disease
This means that they are often very difficult
to control
Look at the sheets about other
alien species!
VIDEO: Cane Toads: An Unnatural
History
• Why Is This Important?
• The reason behind the introduction of cane toads
to Australia was well intended but the results
were unimagined. This is a good example of the
fallibility of scientists and what can happen when
an exotic species invades an ecosystem.
A Natural Balance?
Natural systems operate a dynamic equilibrium – a
moving, changing balance. Weather events or disasters
can alter the balance, but the system gradually adjusts
either to new conditions or revert to previous situation.
With the coming of humans and their domination of so
much of the natural world this balance has been drastically
altered and, in many cases, so quickly that ecosystems
have not been able to adapt.
How can humans influence the nutrient
flow?
• Deforestation
• Over harvesting
• Soil degradation
• Fertilisation
Case Study: Giant Kelp,
California
• Giant kelp is a type of seaweed
which supports a wide range of
species of the coast of California
• It acts as a breeding ground and
nursery for many fish
• One herbivore of the giant kelp is
the sea urchin, which could
destroy the habitat
• The sea otter is the predator responsible for keeping the
urchin at bay
• BUT the sea otter was hunted by humans during the 19th
and early 20th Century
• The whole ecosystem collapsed
• The sea otter is known as a keystone species
Food chain in the kelp forest,
California
What factors threaten biodiversity?
An unsustainably high rate of human population
growth and natural resource consumption
Inequality in ownership, management and flows of
benefits which threatens the lives of the poorest people
Concentration of agriculture, forestry and fishing on a
narrowing spectrum of products
Legal and institutional systems that promote
unsustainable exploitation at the expense of more
sustainable strategies
Lack of knowledge and understanding in the
management and conservation of biodiversity
What are the global factors?
What does this
diagram tell you
about the global
factors?
Demonstrate: Using the factors create a mind map to show
what impact they have.
Climate change
Deforestation
Global threats to biodiversity
What are the local factors to affect
biodiversity?
Fire – used to be used all over Europe and North
America to clear forests for settlements. This is
now used regularly in the rainforest to clear land
for cattle ‘slash and burn’. Causing huge loss of
biodiversity.
Habitat Change – developing natural habitats for
agriculture or urban growth…eventually leads to
loss of biodiversity
Recreational use – often occurs where
ecosystems are vulnerable and plants are
fragile e.g. sand dune system.