Populations & Sustainability Flashcards
Describe and explain the phases of a population growth curve
Slow growth (lag)
- Small numbers of individuals initially present
- Reproduction increases total population
- Birth rate > death rate
Rapid growth (log)
- Number of breeding individuals increase
- Total population multiplies exponentially
- No limiting factors present
- Birth rate > death rate
Stable state (stationary)
- Limiting factors prevent further population growth
- Population fluctuates
- Overall size stays relatively stable
- Birth rate ≈ death rate
Define carrying capacity
Maximum population size an environment can support
Give examples of abiotic factors that limit population size
- Temperature
- Light
- Water or oxygen availability
Give examples of biotic factors that limit population size
- Predators
- Disease
- Competition
Define immigration
- Movement of individual organisms into a particular area
- Causes population to increase
Define emigration
- Movement of individual organisms away from a particular area
- Causes population to decrease
State the factors that would cause an increase in population size
- Increase in quantity or quality of food supply
- Availability of clean water
- Lack of predators
- Favourable environmental conditions
- Availability of light
Define density independent factor
- Factor that has effect on population regardless of its size
- e.g. fire, volcano, storm
- Can remove entire species from an area
Define density dependent factor
- Effect of factor dependent on population size
- e.g. more predators in area = more prey killed
Define interspecific competition
Competition between different species
Define intraspecific competition
Competition between members of same species
When does competition arise?
- When resources are not present in adequate amounts
- To satisfy needs of all individuals who depend on them
Describe what happens to birth and death rates as competition increases
- Rate of reproduction decreases
- Fewer organisms have enough resources to reproduce
- Death rate increases
- Fewer organisms have enough resources to survive
Outline the possible effects of interspecific competition
- Species seeking to occupy similar niche
- Reduction in resources available to competing populations
- If species are equally adapted:
- Reproduction rate decreases in all species
- Population sizes decrease
- If one species better adapted:
- Less well adapted species outcompeted
- Numbers decline
- Potentially to extinction
Define competitive exclusion principle
- Two species compete for same resource
- One that uses resource more effectively will eliminate the other
Describe the cycle of population size changes that occur following intraspecific competition
- Initially resources plentiful
- Population increases
- Birth rate > death rate
- Resources become limited as more organisms compete for resource
- Population decreases
- Birth rate < death rate
- Reduced population results in less competition so more organisms survive and reproduce
- Population increases
- Birth rate > death rate
Define predation
When predator kills and eats prey
What type of competition is predation?
Interspecific
Describe and explain the predator-prey cycle
1 - Increase in prey population - More food for predators - More predators survive and
reproduce - Predator population increases
2 - Increased predator population
eats more prey - Prey population decreases - Death rate of prey > birth rate
3 - Predator population no longer supported by reduced prey population - Intraspecific competition occurs - Predator population decreases
4 - Reduced predator population
results in less prey being killed - More prey survives and reproduce
Explain why predator-prey relationships in the wild may not follow the pattern described above
- Prey not only food source - Predator can get energy by eating another animal(s) - Decrease in particular prey may not cause decrease in predator population
- Predators contract a fatal disease - Prey population increases dramatically
- Natural disaster - Destroys both populations
- Seasonal fluctuations - e.g. larger plant growth in summer - Increases prey food source so population increases
Define conservation
- Maintenance of biodiversity
- Through sustainable human management
Define preservation
Protection of an area by restricting human interference
Describe the differences between conservation and preservation
- Conservation maintains ecosystem
- Involves sustainable management of ecosystem
- Preservation leaves ecosystems undisturbed
Outline the reasons for conserving biological resources
- Aesthetic / recreational value
- Ecotourism
- To preserve biodiversity and genetic diversity
- Natural resources could be useful as potential for medicines
- To support indigenous people
- To stop effect of deforestation on climate
- Moral responsibility for future generations
Define sustainable resource
- Renewable resource
- Economically exploited in a way that it will not run out
What are the aims of sustainability?
- Preserve the environment
- Ensure resources available for future generations
- Enable LEDCs to develop
- Create more even balance between LEDCs and MEDCs in the consumption of resources
Explain how small-scale timber production can be managed in a sustainable way
Coppicing
- Cutting tree stems close to ground
- New shoots form from cut surface
Pollarding
- Cutting stem higher from ground
- Prevents animals eating shoots
Rotational coppicing
- Coppicing different areas each time, to allow time for growth
- Maintains biodiverstiy
Explain how large-scale timber production can be managed in a sustainable way
Selective cutting
- Only largest trees removed
Replace trees through replanting
- Biodiversity, mineral and water cycles maintained
Plant trees optimal distance apart
- Reduces competition, increase yield
Ensure areas of forest remain for indigenous people
Explain how fish stocks can be managed in a sustainable way
Preventing overfishing
- Applying quotas
- Restricting fishing times throughout year
Mesh size increased in fishing nets
- Only mature fish caught, so breeding can continue
How can ecosystems be managed to protect species and habitats?
- Control number of tourists/visitors
- Involvement of local communities
- Education of local communities
- Control the introduction of species
Define ecotourism
- Tourism directed towards natural environments
- Supports conservation
What are the key principles of ecotourism?
- Ensure tourism does not exploit natural environment or local communities
- Engage with local communities on planned developments
- Ensure infrastructure improvements benefit local communities
What are the negative effects of ecotourism?
- Increased erosion of walking trails
- Increased use of 4x4 vehicles
- Causes soil erosion and habitat changes
Give three regions where there is a conflict between conservation and human needs
- Masai Mara region (Kenya)
- Terai region (Nepal)
- Peat bogs (UK)
Describe the ecosystem of the Masai Mara region
Savannah
- Open grasslands with occasional shrub and trees
State and explain the positive impacts of tourism on the Masai Mara region
- People bring economic input into region, which creates jobs and enables region to invest in infrastructure
- Visitors see local tribes, which educates visitors about their traditional way of life
- Research carried out in the Masai Mara, which ensures maintenance of biodiversity in the region
State and explain the negative impacts of tourism on the Masai Mara region
Large visitor numbers requires infrastructure
- Can damage environment and uses natural resources
Visitors require transportation
- Leads to soil erosion and increases pollution
Describe the ecosystem of the Terai region
- Mixture of fertile agricultural land, with densely forested regions
- Hot and humid in the summer months
- Subjected to monsoons
How do humans use the Terai region?
- Agriculture
- Forestry
- Tourism
Describe the sustainable forestry practices used in the Terai region
Local community forestry groups established
- Set agreed prices for timber and reinvest profits for benefit of local population
Sustainable forestry practice has increased forested area
- Larger region available to support biodiverse ecosystem
- Provided improved economic income to the region
Describe the sustainable agriculture practices used in the Terai region
Sustainable agriculture has prevented further intensive agriculture in region
- Retained biodiversity of less cultivated regions
- Improved irrigation of land
- Encouraged multiple cropping to improve fertilisation of land
Describe the ecosystem of peat bogs
Spongy, waterlogged land containing decomposing vegetation
Why are peat bogs under threat?
- Peat used for fuel and as soil additive
- Peat removed from land to supply human demands
- Intensive farming and irrigation has removed water from wetlands
Describe the conservation measures used to protect the peat bog ecosystem
- Maintain water levels by reducing drainage from land
- Removal of tree seedlings from area to prevent water removal
- Using controlled grazing to maintain biodiversity of peatland surface
Describe the effects of human activities on animal and plant populations in the Galapagos Islands
- Increased demand for resources (e.g. water, energy) due to increased tourism
- Waste and pollution increased
- Overfishing has endangered sea-life (e.g. sea cucumbers)
- Many non-native species have been introduced
- Outcompete the native species
Describe the conservation projects put in place in the Galapagos Islands
Goat culling to eliminate non-native species
- Increases vegetation
Giant tortoises bred in captivity
- Increases population size
