populations and sustainability Flashcards
give examples of density dependant factors
biotic:
- predation
- competition
- disease
- CO2 conc. (for plants)
what is density independent factor and give examples
factors that cause death regardless of number in population
e.g. abiotic factors
- climate change
- fire
- volcanic eruption
what are k strategist species controlled by
density dependant factors
features of k strategist species
- controlled by density dependant factors
- invest highly in parental care
- large
- fewer offspring
e.g. chimpanzees
features of r strategist populations
- population exceeds carrying capacity before limiting factors have an effect, causing death phase due to lack of resources.
- low likelihood of surviving to adulthood
- smaller
- produce rapid offspring
e.g. fish
how does intraspecific predation effect population of a species?
competition for same food, water, territory slows down growth so population enters stationary phase and fluctuates around carrying capacity
what is preservation
protecting species/area of land by restricting human activity and keeping it the way it is.
Lead to CLIMAX COMMUNITY
what is conservation
active maintenance of biodiversity and ecosystems by humans which will lead to DEFLECTED SUCCESSION
state 4 methods of control of fish production
- limiting number of fish caught
- limiting fishing to certain times in a year
- set out areas where fishing is banned
- education
state 2 difficulties of controlling production of fish
- area too large to manage
- monitoring can be obstructed by weather
describe small scale rotational coppicing as a method of sustainable timer production
- cut trunk close to ground
- protect young trees from grazers
- allow some trees to grow full size
- repeat process after 9 years
what are 3 benefits of rotational coppicing
- less big trees means more light for smaller plants to grow
- roots remain in soil so prevent soil erosion
- prevents succession
name 3 types of large scale felling
clear felling, selective felling, and strip felling
what are problems of large scale felling
- loss of biodiversity
- disrupting food chains
- soil erosion
how can timber be produced sustainably?
- limit area felled
- replant trees
- allow time for young trees to mature
state the equation to calculate number of bacteria grown over a certain length of time
N = N0 x 2n
0 = initial number
n = number of divisions
why are the number of predators generally smaller?
because they are higher up the food chain
describe the relationship between predator and prey
when the prey population is high, there is more food source available for predators to eat, so pop of prey decline and predator pop increase,
However, now due to lack of prey, there is limited food source so predator pop lowers, and prey pop increases, this cycle repeats.
predator-prey relationships are often more complex - describe the 3 other factors that effect their populations.
- the higher the species diversity in an ecosystem, the more difficult it is to see predator-prey relationships
- if a predator eats several kinds of prey, then it can switch to another if first prey pop declines.
- correlation does not always mean causation, it may be (intraspecific) competition for food, space, mates
why is there a delay before predator population can increase?
because it takes time for birth rate to respond to changing conditions
competitive exclusion
if two species have same niche, one will always outcompete the other, which then dies out.
niche partioning
one species may be pushed into another niche.
when does population level out?
at carrying capacity
why is lag phase slow
- acclimatising to habitat
- genes switching on
- only small population
economic reasons for conservation
- growth of timber, wood, and fuel
- detoxification and recycling of wastes
- source of medicines
how to prevent succession
burning, grazing, coppicing
