Population & sustainability Flashcards
(42 cards)
Name the three different stages in a population growth graph
- Slow growth
- Rapid growth
- Stable state
Describe the slow growth phase
- the small number of individuals that are present reproduce
- the population increases
Describe the rapid growth stage
as the number of breeding individuals increase the population grows exponentially
Describe the stable state
- Further growth is prevented due to limiting factors
- the population fluctuates
- the birth rate = the death rate
What are the limting factors
- Abiotic and biotic
Name the biotic living factors that effect population size
- predation
- competition
- disease
What are the abiotic factors that effect population size
- PH
- Humidity
- temperature
- light intensity
- availability of water etc
What are other factors that can also effect population size?
- migration
- denisty independent factors
Define emmigration
the movement of individuals away from a particular area decreases pop size
Define immigration
the movement of individuals into a particular area increasing the population size
What is a density independent factor?
- factors that effect the population regardless of the size
Define interspecific competition
competition between different species
Define intraspecific competition
competition between members of the same species
What is competitive exclusion principle
( inerspecific competition) the idea that the less well adapted species is more likely to be out competed
Describe the different stages of the intraspecific competition graph
- resources are plentiful & organisms survive and reproduce increase the pop
- resources are now limited & the pop will decrease in size
- decreased population means less indivduals are competing for the same resources. More organisms survive & reproduce and pop increases
Describe the predator & prey graph
- ^prey = more food for predators allowing more to survive and reproduce. Predator pop ^
- Predator pop ^ = more prey are eaten. Death rate > birth rate in prey pop.
- Prey pop decreases = less resources available for predator. they are less able to survive & reproduce. Pred pop decreases
- Reduced pred pop = more prey are able to survive and reproduce. Prey pop ^
Define carrying capacity
the maximum population an environment can support (occurs in stable state)
what are reasons for conserving biological resources
- ecotourism
- to preserve biodiversity
- asestheitc reasons
- species/plants have potential for medicine
What are managment practises used when sustainably producing timber?
- coppicing/pollarding
- selective felling
- rotational felling
- replant trees after felling
what are the benefits of sustainably producing timber?
- maintains biodiversity
- prevents soil eroision
- less disturbance by machinary
Explain how it is possible to produce timber sustainably using clear felling
- limit the size of the area that is felled to reduce soil eroison
- replanting of trees
- minimum distance between replanted trees
- allow time for new trees to fully grow before next felling
- ensure there are protected areas for locals/ natives
Describe the process of coppicing
- coppicing - tree trunk cut close to the ground
- several new shoots grow from the cut surface
- protect young shoots from grazers
- repeat process after certain time
- rotational coppicing
What are the benefits of coppicing?
- new stems grow rapidl than saplings
- life span of tree is extended
- provides variety of light levels
- fewer larger trees means more life for smaller plants
- provides a variety of habitats
- roots prevent soil eroision
- maintains soil quality
- prevents sucession
- large machinary is not needed
Describe the difference between conservation and preservation
- conservation maintains biodiversity and involves the sustainable managment of ecosystem
- preservation leaves ecosystems undisturbed
