Populations + sustainability Flashcards
carrying capacity
maximum stable population size of a species that an ecosystem can support
why is carrying capacity a thing
all individuals have potential to reproduce + grow population
BUT - abiotic + biotic factors that prevent every individual in a population from reaching adulthood and reproducing
Ensure population size limited – why no single population dominates earth
Except humans – overcome many abiotic / biotic factors
Environmental resistance
combined effects of limiting factors that prevent the further increase of a population
Types of limiting factors
Density dependent
Density independent
Density dependent
Factors that affect pop. the more they increase in size e.g resources, predators, intra and inter spp comp.
These limiting factors place the carrying capacity on population size
Density independent
Factors that affect the the same proportion of the population regardless of size
Abiotic factors affecting population size
- Light availability
- Water supply
- Water mineral content
- Temperature
- Amount of space available
- Soil pH
Biotic factors
- Interspecific competition
- Intraspecific competition
- Predation
growth curve
describe growth curve
Types of strategists
k and r
K selection
Offspring have a high prob of survival
Heavy parental care and nurturing
Larger organisms
Much lower reproductive rate
Young are altricial, longer lifespans and have
overlapping generations
Altricial
Born in an undeveloped state and requiring care and feeding by the parents
R selection
Produce many low effort organisms
Species grow rapidly
Found in less competitive and low quality environments
Young are precocial
High of mortality so start reproducing earlier
Non overlapping generations, shorter lifespans
Boom and bust (cyclical)
Precocial
Born in an advanced state and able to feed itself almost immediately
Interspecific competition
between different species
Intraspecific competition
between members of the same species
Interspecific mechanism
Compete for same resource
Reduce availability to both species
If one is better adapted – outcompete the other
Competitive exclusion principle
where two species are competing for limited resource the better adapted one / the one that uses the resources more effectively will eliminate the other
example of interspecific competition
introduction of the grey squirrel into the southern UK caused the native red squirrel to be outcompeted for food and shelter
grey squirrel also carries a disease, parapoxvirus, that is harmless to itself but can be fatal to the red squirrel
intraspecific competition mechanism - 3 stages
effects of competition
competitive exclusion
resource partitioning
character displacement
competitive exclusion
two organisms occupy similar niches – competition
One species slightly better adapted to compete than the other
other species could starve or not find a habitat
second species would then move to find a different niche
possibly evolve over generations to adapt to its new niche
resource partitioning
A particular resource eg. a fruit tree is divided up (partitioned) to satisfy the needs of different feeders
The fruit may be grazed by one species, the leaves by another
The two species are not competing directly for the fruit tree but coexisting on different parts of it
character displacement
Closely related species that inhabit the same geographical region and occupy similar
niches differentiate in order to minimise niche overlap and avoid competitive exclusion
predation mechanism
Stage 1 – increase in prey population provides more food for predators + more to survive + reproduce
Results in an increase in the predator population
Stage 2 – increased predator population eats more prey
Decline in the prey population
Stage 3 – reduced prey population no longer supports predators . intraspecific competition occurs for food
Decrease in predator population
Stage 4 – reduced predator population result in less of the prey population being killed. More survive + reproduce
Increase prey population – cycle repeats
predator-prey graph
Sustainability
the ability of an ecosystem to maintain its biodiversity + productivity over time despite humans deriving their needs from natural resources
Conservation
Active management of ecosystems by humans to maintain biodiversity
Involves management of ecosystem so that natural resources can be used sustainably
involves reclamation
Reclamation
Process of restoring ecosystems that have been damaged
Preservation
Protection of an area by restricting / banning human interference
Ecosystem kept in original state
Focuses on eliminating any human effects on ecosystems
types of reasons for conserving
economic
social
ethical
ecological
economic
Ecotourism – major source of income
Provide resources that human need to survive + provide income
Medicinal drugs / clothes / food / timber
ethical
Many people believe we should not have right to decide which organisms survive
Moral duty for future generations to conserve ecosystems
social
Natural beauty of wild ecosystem
Use for activities beneficial to health – walking / climbing
ecological
more diverse ecosystem is better able to survive and adapt to environmental changes or threats
keystone species
sustainable resource
renewable resource that is being economically exploited in a such a way that it will not run out
aims of sustainability
preserve environment
ensure resources available to future generation
enable less economically developed countries to develop
small scale timber production
coppicing
rotational coppicing
pollarding
coppicing
tree trunk cut close to ground
more shoots form from cut + mature
eventually shoots are cut + more shoots are produced
shoots – used for fencing
rotational coppicing
woodland divided into sections
trees only cut in 1 section until all have been coppiced
then starts in another area
advantages for rotational coppicing
Light is still able to reach forest floor as tress never grow tall enough –> increasing diversity of species
not blocking light - control succession (deflection - plagioclimax) - maintains biodiveristy
allows time for newly coppice trees to grow
quick
disadvantages of coppicing
can be eaten by herbivores
pollarding
similar to coppicing
trees cut 2-3m above grand
advantages of pollarding
herbivores less likely to reach + consume new shoots
disadvantage of pollarding
less new shoots forming
large scale timber production
felling
felling
burning / cutting down large areas of forest
selective cutting
disadvantages of felling
felled trees wont regrow
habitats destroyed
soil minerals reduced
bare soil can be eroded
management of fishing
international agreements made about number of fish that can be caught – fishing quotas
use of nets with larger mesh sizes – immature fish can escape – allow breeding to occur
limiting the size of the fishing fleet by issuing licenses
commercial / residential fishing only at certain times of year – prevent loss of wild species
= protect breeding season
= allows fish levels to increase back to sustainable level
fish farming
- sell larger fish + keep smaller ones and let reproduce
- maintain protein supply
- prevent loss of wild species
Why is preservation not enough to maintain biodiversity
Preservation only keeps the environment as it is
If the ecosystem has already decreased preservation doesn’t prevent further loss
Takes active intervention
masai mara
- ecotourism
- conservation projects
safari tours - provides funding for black rhino conservation project
locals as park rangers - provided more jobs
ecotourism
sustainable tourism focused on observing natural environment that supports conservation efforts and the local people
ecotourism in masai mara
- supports conservation efforts
- takes the needs of the locals into account
- doesnt explot biodiveristy
- balance between needs of local people and local wildlife
advantages of conservation - masai mara
helps protect biodiversity
stops rare plants and animals becoming extinct
deters poachers
local people employed
terai region
sustainle forestry management
sustainable agriculture
- local forest cover has increased
- local people employed and no longer exploiting ecosystem
- biodiveristy protected
multiple cropping introduced to reduce monoculture
fruit and veg grown near mountains to prevent damage to forest
peat bogs
area of land formed from acidic and waterlogged soil
important
habitat for unique ecosystem
carbon sink
prevent flooding
conserve peat bogs
removing trees so water isnt lost
controlled grazing - maintains biodiversity
ditch blockinh - allows water to drain in
galapagos
national parks
park rangers
controlled migration
antartica
visiting heavily restricted
managing tourism
preventing hunting of whales
snowdonia / lake district
national park created
park rangers hired
