6.3.2 - Populations and Sustainability Flashcards
What are the two types of limiting factors in terms of population?
density dependent
density independent
What are density dependent limiting factors?
limiting factors that only effect the population if its too large
eg. predators, disease, food availability, territory
What are density independent limiting factors?
limiting factors that effect the population whatever size it is
eg. natural disasters, climate change, temperature, rainfall
What is the carrying capacity of a population?
the maximum number of organisms that resources in an environment can support
-caused by limiting factors
Describe and explain the shape of a population graph (number of organisms against time)
population starts very small without increasing and then begins to increase at a slow rate
-small no. individuals initially present reproduce (slow)
-birth rate > death rate
rapid population increase
-plentiful supply of resources
-birth rate > death rate
population plateaus
-birth rate slows down
-birth rate = death rate
-carry capacity is reached (due to limiting factors)
Why does the population fluctuate at the carrying capacity?
increases - birth rate and survival rate increase (plentiful resources)
decreases - less resources available/more competition
What is intraspecific competition?
competition within a species
What is interspecific competition?
competition between different species
Why is intraspecific competition more common than interspecific competition?
same species need the exact same resources eg. same food, mates, etc
Describe and explain the shape of a predator-prey graph (number of organisms against time)
prey increase + prey decrease
-more prey survive and have chance to reproduce
-prey reproduction rate > death rate
predators increase
-more prey available as food for predators
prey population decreases
-more predators so more prey are eaten and the death rate of prey increases
-prey death rate > reproduction rate
predator population decreases
-less food (prey) available, leading to competition
-less predators survive and reproduce
What is conservation?
the maintenance of biodiversity by managing the ecosystem
eg. SSSIs, national parks, botanical gardens
What is preservation?
the protection of an area by restricting human involvement
-ecosystem is left alone
What reasons are there for conservation and preservation?
- economic
- social
- ethical
What is sustainability?
the use of resources so that they are available for future generations
What are the aims of sustainability?
- preserve the environment
- ensure resources are available for future generations
- enable less economically developed countries to develop
How can small scale timber production be made more sustainable?
coppicing
eg. willow, beech, ash
- tree trunk is cut close to the ground, where new shoots can form from the cut surface
- rotational
- harvested area increases in biodiversity
selective felling
eg. oak
- only cutting down some trees in an area, leaving the others to grow more
How can large scale timber production be made more sustainable?
selective/rotational felling and replanting
What are the advantages of selective/rotational felling and replanting?
- increases biodiversity
- replanted trees can be spaced apart to prevent disease
What are the disadvantages of clear felling?
very environmentally damaging
- habitat loss
- soil composition (minerals/ions) lost
What is clear felling?
large scale timber production where all the trees are cut down
What is coppicing?
tree trunk is cut close to the ground, where new shoots can form from the cut surface and grow to create new plants
- done on a rotation
- usually on small scale timber production
What is pollarding?
coppicing when tree trunks are cut higher up to prevent deer, etc eating the new shoots
How can fishing be made more sustainable?
fishing quotas
controlling mesh size of nets
How are human activities controlled in environmentally sensitive ecosystems?
park authorities (Snowdonia, Lake district)
-promotes understanding of park
-conserves + enhances wildlife, natural beauty and cultural heritage
Antarctic treaty (Antartica)
-tourism management
-conservation of plants and animals
-protected areas managed (eg. limited visits)
-scientific cooperation between nations
limiting human access (Antartica, Galapagos Islands)
controlled migration (Galapagos Islands)
