Transcript 6.3.2 populations and sustainability student version

5.3.2 Populations and
Sustainability
By Ms Cullen
Or
Should Ms Cullen go to the
Galapagos Islands?
Learning Objectives
• To recognise that many different factors will
determine population sizes.
• To explain the significance of limiting factors in
determining the final population size.
• To use the Galapagos Islands as an example of
the need for a balance between conservation
and ecotourism and to discuss how they can
be managed to lessen the impact of human
activity on the islands.
Population growth
Population growth in r-strategist species
Predator/Prey Relationships
Predator/Prey Relationships
Can you explain the graph?
Competition
There are two types of competition:
• Intraspecific competition – this occurs
between members of the same species.
• Interspecific competition – this occurs
between members of different species.
Intraspecific competition
• As population numbers
drop, so will
competition within a
population.
• Conversely as
population numbers
rise, so will competition
for resources between
individuals.
Interspecific competition
• This can affect both size
(abundance) and
distribution of
populations within an
ecosystem.
Allelopathy
• Allelopathy is when an organism produces one or more
biochemicals that influence the germination, growth, survival,
and reproduction of other organisms.
• It is a form of competition because it prevents the plant’s
neighbours using the resources in the habitat.
• These biochemicals are known as allelochemicals and can have
beneficial or detrimental effects on the target organisms and
the community.
• Allelochemicals are a subset of secondary metabolites, which
are not required for metabolism of the organism that produces
them.
• Allelochemicals with negative allelopathic effects are an
important part of plant defense against herbivory.
Allelopathy
• Allelopathic chemicals can be found in almost any part of the
plant; they may be released from roots directly into soil or
leached out of leaves or fruit when a plant sheds them.
• Examples:
• The black walnut tree releases a chemical called juglone. This
inhibits respiration in younger plants.
• Why do you think this is advantageous?
• The cereal plant sorghum releases sorgolene through it’s
roots, disrupting photosynthesis and respiration in
neighbouring plants.
• Why do you think this is advantageous?
• Many invasive plants use allelopathy eg spotted knapweed
• Allelopathy is also known as chemical competition.
Conservation or preservation?
What is the difference?
Why do you think we need to
conserve species and resources?
Brainstorm:
Economic reasons
Ecological Reasons
Aesthetic and Ethical Reasons
Sustainability
• Successful management of resources leads to
sustainability.
• Sustainability is the management of a resource or
system, so that it is replenished at the same rate that
it is used.
• Sustainability has become increasingly important as
our world population grows and their is increasing
competition for resources.
• Can you think of examples of sustainability?
Sustainability is……….
Galapagos and tourism
Ecotourism
The World Conservation Union and the
Ecotourism Society define eco-tourism as
“responsible travel to natural areas that
conserves the environment and sustains the
wellbeing of local people” (Blangy and Wood,
1993).
Human Impact on Galapagos?
Galapagos Islands - ecotourism
Threats
• Increased population
• Overfishing
• Tourism
• Why have these issues
become threats?
• What can be done to
limit the impact?
• Can some of them be
advantageous?
• How would you
promote ecotourism
and responsible
travelling?
Ecosystem Management
Case Studies
Ecosystem Management – The Masai Mara
National Reserve (MMNR)
• Savannah ecosystem
divided by Mara river
• Closer to river has
fertile woodland and
grassland ecosystems
• MMNR is famous for
zebra and wildebeest
migrations
• Named after local
nomadic tribe the
Masai
Farming in the MMNR
• Traditionally semi-nomadic farming, where livestock
graze depending on climate variation and presence
of tse-tse fly.
• What is the benefit of this method?
•
• Local tribes are now prevented from entering the
park, limiting grazing to the edges of the reserve
• What effect do you think increased populations will
have had?
Ecotourism in MMNR
What needs to be addressed?
Conservation and Research in
MMNR
MMNR plays an important role in conserving many
endangered species.
The Black Rhino Diceros bicornis (on IUCN critically
endangered list)
Why?
Numbers declined from 100 in 1972 to a handful of
individuals in 1982
Conservation and Research in
MMNR
• Active conservation programme has been set up to
address the balance between local people and
wildlife
• The aim is:
•
•
•
•
Ecosystem Management – The
Terai region of Nepal
• Southern part of Nepal
• High population density
• Rich fertile alluvial soil,
exploited for agriculture
• Incredibly biodiverse; subtropical areas and thick forest
• Important source of national
income
• Deforestation has
exacerbated effects of
monsoon flooding
• If this continues only isolated
pockets of forest will be left
Ecosystem Management – The
Terai region of Nepal
40% of land in Nepal
was forested
This area was
decreasing by 1.9%
in 1990s!
Ecosystem Management – The
Terai region of Nepal
National legislation and the formation of local community forestry
groups has allowed this to happen, these local networks and
businesses can work together to achieve Forestry Stewardship Council
(FSC) certification. An internationally recognised reward for
sustainable forestry.
Successes include:
Ecosystem Management – The
Terai region of Nepal
Management strategies for sustainable land use include:
 Promoting fruit and vegetable growth in hill region to avoid further
intensive faming of Terai region
 Improving irrigation to enhance
crop
production
Since
2000
the
forest
 More than 1 crop is grown on decline
a piecein of
land each growing season –
areas has reversed
multiple cropping
and forest coverage
 Growth of nitrogen fixing crops
to increasing
enhancesoil fertility
is now
 Growing crop varieties resistant to abiotic and biotic challenges
through modern biotechnology and genetic engineering
 Improving fertilisation techniques to enhance crop yields, eg using
manure to improve soil
Ecosystem Management – The
Terai region of Nepal
Q: Explain how sustainable forestry and agricultural
practices are being used in the Terai region to maintain
biodiversity, while also meeting the needs of the local
population (4 marks)
Ecosystem Management – Peat
Bogs
Ecosystem Management – Peat
Bogs
• Region of wet, decaying vegetation, formed by
anaerobic and acid conditions inhibiting
In the UK, lowland raised
decay.
bog is estimated to have
decreased
by to
overform
90%
• Take thousands of
years
From 950km to only 60
in last 100 years 
• Carbon sink
• Peat can be used as a fuel once dried or as a
soil improver to increase acidity and structure
of soil
• Why are they at risk and why is this such a
concern?
2
Why should we conserve peat
bogs?
How can we conserve peat bogs?
To conserve lowland bogs water levels need to be
maintained/restored, strategies to ensure this include:
 Leave surface of bog undisturbed and wet. Ditches should
surround bogs to prevent flooding of neighbouring land.
 Removal of seedling trees, as trees use huge amounts of
water during transpiration and can dry out bogs and prevent
growth of bog vegetation.
 Controlled grazing and/or burning of wetland. Promotes
species diversity.
Organisations such as RSPB, The Wildlife Trusts and Natural
England are working to preserve peat bog ecosystems.
What impact do human activities have in
environmentally sensitive areas? Antarctica
How can we control the effects of human
activities in environmentally sensitive
areas? - Antarctica
Ideas?
How can we control the effects of human
activities in environmentally sensitive
areas? – Lake District National Park
• Ideas?
How can we control the effects of human
activities in environmentally sensitive
areas? – Snowdonia National Park
• Ideas?
Home study:
Sustainability – Research and notes on small and large
scale timber production – coppicing, pollarding etc and
sustainable fishing.
Start with Kerboodle P.639-641. Then find more
information, data (especially on fish population
numbers) and images off the internet & include refs!