Populations And Sustainability Flashcards
Carrying capacity?
Maximum stable population size of a species than an ecosystem can support
Abiotic factors that are limiting factors of population size?
Non living parts of ecosystem :
Light availability
Water supply
Water mineral content
Temperature
Amount of space available
Soil pH
What are limiting factors ?
Conditions that prevent populations from increasing indefinitely by restricting access to essential resources
Limiting factros fall into 2 categories:
DENSITY INDEPENDENT- their impact remains constant regardless of pop size/can lead to extinction (natural disasters)
DENSITY DEPENDENT: their impact increases as the pop size increases (competition for resources)
Biotic limiting factors of population size?
Involve the living parts of an ecosystem
3 types of BIOTIC factors:
INTERSPECIFIC competition (between different species)
INFRASPECIFIC competition (within a species)
PREDATION
What happens to a population when carrying capacity is reached?
- Birth and death rate EQUALISE
- Pop growth slows down + pop size stabilises with some fluctuations
- If environmental conditions degrade , pop size might decrease (sometimes drastically)
Population growth curve?
- Slow growth - birth rate exceed death rate so pop starts to grow
- Rapid growth - population expands EXPONENTIALLY when there are no significant restrictions on its growth
- Stable state - limiting factors stop further growth leading to stable population growth size - carrying capacity reached
INTERSPECIFIC competition : the Competitive Exclusion Principle?
Suggests that when 2 species are competing for same limited resources , the species that uses these resources more efficiently/better adapted to surroundings will eventually OUTCOMPETE the other
- the species that outcompetes the other has greater chance of survival/reproduction
- So one population of species increases and the other decreases
Impacts of INTERSPECIFIC competition on populations?
- competition between 2 species will reduce resources available for both populations
- so less chance of survival/reproduction, due to fewer resources
- so both populations will be limited
usually occurs when the 2 species are similarly well adapted to habitat - Competitive exclusion principle - one species will outcompete another who have similar niches
- outcompeted species finds different niche or evolves to adapt to its new niche
Intraspecific competition impacts on populations?
Results in natural population fluctuations:
1. When resources are plentiful, survival and reproduction increases -> RISE IN POPULATION
2. Larger pop means INCREASED COMPETITION, reducing available resources —> POPULATION DECLINE
3. Decrease in competition allows for greater access to resources leading to POPULATION RECOVERY and then cycle starts again
The predator-prey relationships?
- Increase in prey , provide more FOOD for predators —> PREDATOR POP INCREASES
- Rise in PREDATOR POP causes more predation of prey —> DECREASE IN PREY POP
- Lack of prey increase COMPETITION among predators for food—> predator numbers DECREASE
- Decrease in predators allows prey populations to survive and reproduce more successfully - PREY NUMBERS RISE (restarts cycle)
In stable community , this limits population sizes of both predators and prey
Conservation?
Involves the protection and management of ecosystems to ensure natural resources are used sustainably , maintaining biodiversity through HUMAN ACTION
- dynamic process - conservation methods need to be adapted to the constant changes in ecosystems
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Preservation?
Maintainence of habitats and ecosystems in their present condition
- restricts resource extraction/human interference
What does conservation require?
Management - humans control the use of resources/their replenishment
Reclamation - humans restore damaged ecosystems for future use
Reasons for conservation?
Ethical - all organisms have the right to exist/we have moral responsibility to prevent extinctions/loss of biodiversity caused by humans
Social - aesthetic/recreational value enhancing quality of life and well-being
Economic - provide resources for local/global trade - meds from microorganisms/plants
Ecotourism - tourists to national parks /provide jobs and brings in money
What sustainable development? Aims of sustainability?
Management of ecosystems in a way that allow for the economic exploitation of natural resources without them running out
Aims:
Preserve environment
Make resources available for future gens
Allow all humans to live comfortably
Support development in LEDCS
Achieve more balanced consumption of resources globally
Example of sustainable management of ecosystems: COMMERCIAL FISHING?
- want to ensure long term viability of fish stocks
Sustainable fishing techniques:
Fishing quotas - Set limits on the numbers of certain species that can be caught in specific areas
Fish farming - Provides a sustainable source of protein while conserving wild fish populations.
Mesh size regulations - nets have minimum mesh size so smaller/juvenile fish can escape
Seasonal fishing restrictions - Protect fish during breeding seasons so populations recover before fishing resumes
Banning certain practices - static nets that catch all species / agreeing certain areas to BAN fishing and PERMIT fishing
Example of sustainable management of ecosystems: TIMBER PRODUCTION
Sustainable forestry for small scale timber production:
Coppicing - cutting (deciduous) trees close to ground and new shoots grow from cut surface and mature
Rotational coppicing: coppicing different areas sequentially allowing time for recovery before revisiting an area
Pollarding : cutting trunk higher up to protect new shoots from being eaten by animals / same benefits of coppicing
Example of sustainable management of ecosystems: TIMBER PRODUCTION
Sustainable forestry for large scale timber production?
Selective cutting - Removing largest trees to allow growth of younger trees
Clearing small patches in woodland - promotes quicker regrowth.
Avoiding large exposed clearings - prevents soil erosion.
Leaving some areas - supports the livelihoods of Indigenous communities.
Spacing out plantings - Reduces competition for light —> better yields
replant native tree species - maintain biodiversity and water/nutrient cycles
Provide support/ protection for saplings - Improves chances of survival
Managing pests and pathogens - Essential for maximising yields
Advantages of sustainable forest management?
Improves conversation,soil and water management
Increase retail price of forestry products - more employment/income
Provide sustainable wood fuel sources
Secures biodiversity
Human activities affecting plant and animal populations?
Climate change-burning fossil fuels
Introduction of non-native species
Hunting
Degradation/loss of habitats
Affects of burning fossil fuels on populations?
Large scale burning —> high levels of CO2 in atmosphere —> global warming
Higher temps cause:
Changes in weather patterns
Melting polar ice caps
Rising sea levels - flooding/salination of soil
Rising ocean temps/acidity
These effects change habitats
How has the introduction of non-native species affected populations?
Introduction of non native species can occur due to : keeping animals as pets
- growing attractive plants in gardens
- introduction of biological pest control
- Non native species don’t have any NATURAL COMPETITORS, predators or pathogens that limit population growth —> POP GROWS QUICKLY
- Non native species negatively affects native species due to competition/disease
How does hunting affect populations?
Hunting can result in over exploitation of natural resources
- hunting too much can lead to extinction
Prevented by doing this sustainably (e.g sustainable fishing practices)
How has habitat loss affected populations?
Humans reduce/damage habitats by:
Deforestation
draining of wetlands for farming
Pollution of air,water,soil
If habitat is reduced, species will search for new habitat and/or compete for remaining habitat
- range of habitat is so small —> can lead to extinction
Controlling effects of human activities of plant/animal populations?
- prohibit import/export of species
- put restrictions to control impact of humans on populations (e.g certain areas not used for agriculture,housing etc)
- reduce sources of greenhouse gases
- increase capacity of “sinks” that store greenhouse gases (e.g oceans/forests)
Example : The Terai Arc :
how conservation/preservation is balanced with human needs?
An area of forest/grasslands on Border of Nepal and India
endangered species : Asian elephant/bengal tiger found there
Forest area destroyed for housing/development —> brings animals/human in closer contact —> MORE CONFLICT (tigers kill livestock/elephants trample crop fields)
WWF —> provided solar cookers/biogas generators so wood not needed for fuel
Farmers encouraged to plant mint hedges around crops to keep animals away
Example: The Maasai Mara: how conservation/preservation is balanced with human needs?
National reserve in Kenya - grassland home to WILDEBEEST/ZEBRA, lions and cheetahs
Maasai ppl earn by raising livestock (cattle) but leads to conflict with conservationists - overgrazing by livestock destroy grassland
Conservations trusts help Maasai ppl earn from their land through conservation/ecotourism instead of farming / help farm sustainably
Example : UK peat bogs :
how conservation/preservation is balanced with human needs?
Peat bogs - areas of wet peat (store water/CO2) and home to plants/animals
- a specific moss also helps peat bogs to retain water
used to graze sheep/deer -> conflict with conservationists as:
overgrazing causes loss of moss species, soil compaction (increases water runoff down sheep paths) /peat bog erosion
Government funded schemes: Environmental stewardship scheme given farmers money to use peat bogs sustainably
E.g carry out measures to reduce water runoff
Lower no. Livestock that use peat bogs
