6.3.2 - Populations and Sustainability Flashcards
What is carrying capacity?
The maximum population size that can be indefinitely supported by an environment
What is a limiting factor (populations)?
An environmental resource or constraint that limits population growth
Why can’t population growth be sustained indefinitely?
There are many biotic and abiotic limiting factors that prevent every individual in a population from reaching adulthood and reproducing
This ensures the size of each species os limited at some point (ie carrying capacity is reached)
What is a population growth curve?
Shows growth of a new population over time
Most natural populations will show the same characteristics
3 main stages:
1) slow growth (lag phase)
2) rapid growth (log phase)
3) stable state (stationary phase)
What is slow growth (lag phase)?
- small population that are reproducing
- not a significant increase due to small population
- birth rate higher than death rate
- population adjusting to new conditions
What is raid growth (log phase)?
- as number of breeding individuals increases, total population multiplies exponentially
- no constraints acting to limit the population explosion
What is the stationary phase?
- further population growth prevented by external constraints (limiting factors)
- population size fluctuates but remains relatively stable
- birth and death rate approximately equal
What are abiotic limiting factors (populations)?
Non-living components of the environment that affect the population size
Eg • temperature • light • pH • availability of water/oxygen •humidity
What are biotic limiting factors (populations)?
Limiting factors caused by living part of an ecosystem and interactions between organisms
Eg
• predation
• competition
•diseases caused by microorganisms
What is immigration?
The movement of individuals into an area
Increases population size
What is emigration?
The movement of individuals away from an area
Decreases population size
What are density independent factors?
- have an impact on whole population regardless of size
- can dramatically change population sizes
- eg earthquakes, fore’s, volcanic eruptions, storms
What are some examples of how ecosystems are managed to balance the conflict between conservation/preservation and human needs?
- Masai Mara region of Kenya
- Terai region of Nepal
- Peat bogs
How is the Masai Mara National Reserve (MMNR) of Kenya being managed to reduce the conflict between conservation/preservation and human needs?
Large area of grassland home to huge populations of wildebeest, zebra etc
CONFLICTS:
• Masai ppl traditionally earn living by raising livestock, but overgrazing by livestock can destroy grassland
•poaching allows them to earn living but lowers animal population numbers
• elephants trample on crops
SOLUTIONS:
• Conservation trusts are working with ppl so they can earn from land through conservation + ecotourism and farm in a sustainable way
• legal hunting of overpopulated species allowed at certain times, park rangers employed and provided with equipment
• farmland fenced off to prevent elephants
Economic needs of people are met while allowing area to be conserved
How is the Terai region of Nepal being managed to reduce the conflict between conservation/preservation and human needs?
Area of forest and grasslands. Variety of plants/animals there, including endangered bengal tiger. Almost 7 million people live and depend on forests resources to survive
CONFLICTS:
• forest being cut for resources (eg wood for fuel), destroying habitat
• forest being cleared to make space for houses, bringing humans and animals closer and causing conflict (eg tigers can kill livestock, but may be shot and killed themselves)
SOLUTIONS:
• increased retail price of forestry products, so greater economic input
•sustainable fuel sources to prevent overuse of wood
•employment in forest protection and production of non-timber products
• growth of nitrogen-fixing crop and using manure to enhance soil fertility
• promoting production of fruits and veg in hills to avoid further deforestation
• using genetic engineering to grow crops resistant to soil, climatic and biotic challeng
How are UK peat bogs being managed to reduce the conflict between conservation/preservation and human needs?
Peat bogs are areas of wet peat that store water and CO2. Take thousands of years to form. They are home to lots of different plants and animals
CONFLICT:
Used to graze sheep and dear, but overgrazing causes:
•loss of moss species
• soil compaction, increasing water runoff and taking sediment with it
• general peat bog erosion
SOLUTION:
• gov funded programs eg Environmental Stewardship Scheme give farmers money to use peat bogs in sustainable way eg reduce livestock grazing
• no large trees planted nearby - they will remove the water
What are environmentally sensitive ecosystems?
Ecosystems that are less resistant to change than others
What kind of management techniques can be used in environmentally sensitive areaS?
- limiting areas tourists can visit
- controlling the movement of livestock
- introducing anti-poaching measures
- replanting of forests and native plants
- limiting hunting through quotas and seasonal bans
What are the effects of human activities on the Galápagos Islands?
Non-native animals and plants have been introduced, which compete with native species
This decreased the native population
What methods of control have been introduced in the Galápagos Islands?
- Galapagos national park established in 1959
- introduction of Park rangers across the iPads
- controlling migration to/from islands
- strict controls over movement of introduced animals
- limiting number of tourists
What are the effects of human activities on Antarctica?
- visitors have caused pollution by dumping sewage in sea and leaving rubbish
- shipping accidents led to oil spills, which severely affect wildlife
- hunting, whaling and fishing have reduced wildlife populations in the area
- global warming has led to ice melting
What is the Antarctic treaty?
Established 1961 to protect Antarctica. Provisions include:
• scientific cooperation between nations
• protection of Antarctic environment
• conservation of plants and animals
• designation and management of protected areas
•management of tourism
What are the effects of human activities on the Lake District and Snowdonia?
Many visitors go walking, leading to the erosion of foot paths and loss of soil from hillsides
Soil that ends up in waterways/lakes can affect pH, causing knock-on effects for wildlife
As paths become harder to walk on, people can start to trample and destroy sensitive vegetation other side of paths
What are the key purposes of the park authority for Snowdonia national Park?
Conserve and enhance the natural beauty, wildlife and cultural heritage of the area
Promote opportunities for the understanding and enjoyment of the special qualities of the park
Enhance the economic and social well-being of communities within the park
What does the Lake District National Park Authority do?
Like Snowdonia - conserves the region while enabling access for millions of visitors each year
Aactive management of the countryside (eg replanting native tree species)
Why do prey/predator numbers fluctuate?
STAGE 1
• increase in prey population provides more food for predators
• more predators survive + reproduce, so greater predator population
STAGE 2
• increasing predator pop eats more prey, causing decline in prey population
• prey death rate > birth rate
STAGE 3
• larger predator pop not supported by declining prey numbers
• intraspecific competition increases
• decrease in predator population
STAGE 4
• reduced predator numbers result in less of the prey pop being killed
• more prey will survive and reproduce, increasing prey population
This cycle repeats
What is intraspecific competition?
Between members of the same species
• Availability of the resource determines population size
What is interspecific competition?
Between different species
Results in a reduction of the resource available to both populations
Outline the interspecific competition between grey and red squirrels
Red squirrel = native
Grey squirrel = invasive
Grey outcompeted red
• eats wider range of food
•larger so can store more fat
As grey pop increased, food supply for red decreases more
What is a niche?
It’s role in the community
What is the competitive exclusion principle?
No two species can occupy the same niche indefinitely when resources are limiting
When 2 species are competing for the same food source but one is better adapted, the less well adapted is likely to be outcompeted
Why does intraspecific competition result in fluctuations in population size?
1) if the resource is plentiful, all organisms have enough to survive and reproduce. Population increases
2) increased population means resources are now limited. Not enough of the resource is available to support population. Population decreases - intraspecific competition
3) less organisms in the smaller population. More organism can survive and reproduce and reproduce, causing the population to increase
What is conservation?
The maintenance of biodiversity though human action or management
What is preservation?
Protection of an area by restricting or banning human use (ecosystem is kept exactly as it is)
What is the importance of conservation?
ECONOMIC
• provides resources humans need to survive and to provide income
• medicines, timber, clothes, food
• ecotourism
SOCIAL
• people enjoy the natural beauty of wild ecosystems
• used for activities for health (relaxation and exercise) - walking, running, birdwatching etc
ETHICAL
•all organisms have a right to exist and most play an important role within their ecosystem
•have a moral responsibility for future generations to conserve wide variety of ecosystems
What is a sustainable resource?
Renewable resource rage s being economically exploited in a way that it wont diminish or run out
What are the aims of sustainability?
- preserve the environment
- ensure resources are available for the future generations
- allow humans in all societies to live comfortably
- enable less economically developed countries (LEDCs) to develop through exploiting their natural resources
- create a more even balance in the consumption of these resources between more economically developed countries (MEDCs) and LEDCs
How can timber production be made sustainable on a small scale?
COPPICING
• tree trunk cut close to the ground
• new shoots form from the cut surface and mature
•eventually these shoots are cut again and the cycle repeats
• rotational coppicing - divide woodland into sections and coppice on at a time
POLLARDING
• similar to coppicing
• trunk is cut higher up
• deer and other animals can’t eat new shoots
How can timber production be made sustainable on a large scale?
Large scale based on felling large areas of forest - trees wont regrow
Ensure sustainability:
• selective cutting (removing the largest trees only)
•replace trees through replanting (natural regeneration takes too long)
• plant trees at an optimal distance (reduce competition)
• manage pests/pathogens (increase yield)
• areas o forest remain for indigenous people
How can fishing be made sustainable?
INTERNATIONAL AGREEMENTS
• common fisheries policy in EU
• fishing quotas
•aim to maintain natural population of species
• fish can reproduce sufficiently to maintain population size
NETS AND MESH SIZES
• large enough so small, immature fish can escape
• allow breeding of populations to continue
FISHING AT CERTAIN TIMES OF THE YEAR
• protect breeding season, allowing numbers to increase to sustainable level
FISH FARMING
•maintain supply while preventing loss of wild species
