Populations and sustainability 6.6 Flashcards
(28 cards)
What are the factors that determine the size of a population (limiting factors)?
- food
- mates
- O2
- light
- space
- predators
- territory
- water + minerals
- pathogens
What is the carrying capacity?
The maxiumum population size that can be maintained over a period of time in a particular habitat
- populations can no exceed carrying capacity
What are K strategists?
- populations where the size is determined by the carrying capacity
- limiting factors exerft a more and more significant effect as population size gets closer to carrying capacity
Eg/ birdls, large mammals, large trees
What are characteristics of K strategists?
- low reproductive stage
- slow development
- late reproductive stage
- long lifespan
- large body mass
What are R strategists?
- populations where the size can increase so rapidly it can exceed the carrying capacity before limiting factors start to have effect
- once the carrying capacity is exceeded there are no longer enough resources to allow individuals to reproduce or even survive
- excessive buildup of waste products start poisoning the species and they begin to die entering a death phase
Eg/ insects, spiders and weeds
What are the characteristics if R strategists?
- high reproductive rate
- quick development
- young reproductive age
- short life span
- small body mass
What is interspecific competition?
Competition between different species
What is intraspecific competition?
Competition within a species
What are the effects of predators on prey populations?
- an increased number of predators will cause a decrease in the population size of the prey
- a decreased number of predators will cause an increase in the population size of the prey
What are the effects of prey on predator populations?
- an increase in the number of prey will cause an increase in the population size of the predators
- a decrease in the number of prey will cause a decrease in the population size of the predator
What is conservation?
The maintenance of biodiversity (between species abd genetic diversity within species) and the maintenance of a variety of habitats and ecosystems (active process)
What is preservation?
Maintenance of habitats and ecosystems in their present conditions, minimising human impact (passive process)
What are the economic reasons for conservation of biological resources?
- many medicines used originate from plants, fungi and bacteria
- ecotourism is a major source of income for many countries
- ecosystems have made major contributions to the field of science and technology
What are the social reasons for conservation of biological resources?
- many people enjoy spending time in the natural environment
- there are many activities that people can do together in nature
- aesthetic reasons like humans finding joy in the beauty of nature
Eg/ birdwatching, walking
What are the ethical reasons for conservation of biological resources?
- humans have a moral obligation to prevent the loss of biodiversity that result from human activities
- humans share the planet with other species and have no right to cause extinction of other species
- humans are the most intelligen species on the planet so the responsibility falls on their shoulders to protect and value all the organisms on the planet
What are the environmental reasons for conservation of biological resources?
- plants absorbe CO2 from the atmosphere and help reduce the greenhouse effect and climate change
- microogranisms break down masses of organic waste that are produces by larger organisms
- transpiration of plants and ther contribution to the water cycle provides human with drinking and irrigation water
- fungi and bacteria form a major part of the nutrient cycle to allow further plant growth
- producers in food webs provide a direct and indirect energy source for humans
What is sustainability?
The ability of an ecosystem to maintain its biodiversity whilst simultaneously providing humans with the resources they need over a long period of time
How can ecosystem management provide resources in a sustainable way?
- the resources must be allowed sufficient time to replenish before it is harvested so it does not run out
- no harm should be done to the ecosystem, surrounding areas or species living within it
- practices that boost biodiversity are promoted
- long-term future for the ecosystem must be garanteed
What are the examples of ecosystem management?
- commercial fishing
- timber prodction
How are ecosystems managed for timber production?
- coppicing - felling trees close to the ground (done on rotation) to allow fast regrowth of timber
- pollarding - trees are cut 2-3 metres abover the ground
- firebreak
- creating wide edge habitats to attract wild plants, insects and birds
- fallen trees left to rot insitu, returns nutrients and provides shelter
- strip felling to give wide age profile of trees
How are ecosystems managed for fishing?
- fishing quotas
- agreeing areas where fishing is banned and permitted
- regulating mesh size of nets to allow smaller fish to escape
- limiting the size of fishing fleet by issuing licenses
- inspecting the catch as fishing boats return to port
- banning certain practices (gillnets)
What are the human activities that are having an effect on the animal and plant populations?
- burning fossil fuels
- introduction of species
- hunting
- habitat loss
How is burning fossil fuels affecting populations?
- increases levels of CO2
- results in higher average global temperature
- this changes weather patterns, melts polar ice caps, rises sea levels, causes flooding and rises ocean temperatures and acidity
- the effects have changed the habitats of some species putting their survival at risk
How is introduction of new species affecting populations?
- introduction of non native species can happen due to travel, keeping animals as pets, growing attractive plants in gardens and introduction of bologican pest control
- non-native species often have no natural competitors, predators or pathogens to limit population growth
- populations grow very quickly
- negatively affects native species through competition and disease
