10.1- the nature of ecosystems Flashcards
habitat definition
the area or natural environment in which an organism or population normally lives
ecosystem definition
a biological community of organisms which interact with each other and their physical environment
community definition
all the organisms present in an ecosystem at a given time
population definition
a group of individuals of the same species that occupy the same habitat at the same time
niche definition
a term for the position of a species within an ecosystem
biome definition
a specific environment that’s home to living things suited for that place and climate e.g. desert or tropical rainforest
biodiversity
the number and variety of living organisms in the living world
what are abiotic factors
-non living elements of a habitat or organism
abiotic factors example
-air
-water
-light
-wind
-soil
-pH
-temp
-humidity
-inorganic nutrients
what are biotic factors
-the living elements of a habitat that affect the ability of a group of organisms to survive there
biotic factors examples
-other organisms so..
-competition
-predation
-symbiosis (mutualism and parasitism)
-disease agents
climatic abiotic factors
-factors include humidity, sunlight and factors involving the climate
edaphic abiotic factors
-soil conditions, so edaphic abiotic factors include soil and geography of the land
topographic abiotic factors
-physical features of an area including height, direction of slope and steepness of slope
what is succession
-the process of a community changing over time
-heavily influenced by conditions in the environment
how does succession happen
-community consists of all plants and animals in particular area
-individual populations in a community interact
-the community is constantly changing and dynamic, which passes through a number of stages from origin to climax
-transition from one stage to next is succession
primary succession
-progressive colonisation of bare rock or barren terrain by living organisms
secondary succession
-the recolonization of an area after an earlier community has been removed or destroyed
primary succession in steps
-pioneer species begins breaking down rock
-lichens usually grow on rock
-Lichens secrete acids that begin breaking rock into small particles
-more complex plants grow when soil is deep enough
-eventually succeeds lichens
-organic material can hold water
-larger complex plants
-forests if soil deep enough
-Climax community
Is very stable and can endure for hundreds of years.
overall features that emerge in succession
-The abiotic environment becomes less hostile (e.g. soil forms).
-More complex food webs.
-Increased biomass.
-Increased biodiversity – increase in number of species.
-Greater number and variety of habitats and niches.
succession stages summarised
-grassland, small flowering plants
-tall herbaceous plants
-bushes and shrubs
-fast growing trees
-larger, slower growing strong trees
summary of succession (mark scheme)
1.Pioneer species/mosses/lichens arrive
2.decomposition increases the soil depth and mineral/nutrient content.
3.Therefore larger plants can grow.
4.More herbaceous plants/shrubs/trees are present.
5.Nitrate content in soil grows as there are more leaves/plants/animals/faeces.
6.Climax community emerges at end.
where does secondary succession take place
areas where life is already present but has been altered in some way
-faster than primary
3 main causes of secondary succession
1.natural catastrophe (fire)
2.human destruction
3.human management (ploughing)
2 main ways of sampling
-systematic
-random
random sampling
-used in large area which is very uniform
1.numbered grid- lay grid over, random number generator
2.random walk-Each sample point is located by taking a random number between 0 and 360, to give a compass bearing, followed by another random number which indicates the number of paces which should be taken in that direction.
how to use quadrats
-only count if plant mostly in
-if large abundance, count percentage cover
systematic sampling
-used to see change in species
-lay transect, record at regular intervals
-stop when there’s no further change
sampling techniques
-pitfall trap
-tullgren funnel
-beating tray
-pooter
-kick net
-sweep net
abiotic factors- light
-needed for photosynthesis
-at low light intensity plants may have extra chlorophyll
-Animals are sensitive to light level indirectly as a result of the distribution of food plants.
abiotic factors-temperature
-extremes of temp determine whether organisms can live
-temp controls rate of enzyme controlled reactions
abiotic factors- wind/water
-wind can inc water loss from body, cooling
-in currents organisms must be able to;
-be strong swimmers
-attach to surface or
-flow with current
abiotic factors- water availability
-effected by amount of rainfall, rate of evaporation and rate of soil drainage
abiotic factors- oxygen
-in water or soil
-if soil is water logged there may be a lack of oxygen
how does competition occur
-when 2 or more organisms share resources that is insufficient to satisfy them fully
intraspecific competition
-when individuals in the same species compete for resources
-availability of resources determine size of population
-larger availability= larger population
interspecific competition
-when individuals in different species compete for resources
-usually one has a competitive advantage
-could lead to removal of one species
-known as competitive exclusion principle
biotic factors- predation
-populations where predation in present will oscillate in repeating cycles
-because as prey increases there is more food for predators
-pred population inc until the point where they are eatinf more than they produce, so not enough food for offspring so numbers decrease
biotic factors- finding a mate
-single organisms cannot populate an entire habitat
-organisms must have mates to reproduce
biotic factors- territory
-A territory is an area held and defended by an animal or group of animals against other organisms.
- ensure that a breeding pair has sufficient resources to raise their young.
-Territory type and size of a territory helps to determine which species can live there.
biotic factors- parasitism and disease
-diseased animals cannot reproduce successfully
-sick predators cannot hunt
-parasites effect hosts by feeding on them and therefore weakening them
-spread more rapidly in high population
-fewer effects if biodiversity is high
density dependent limiting factors
-factors which depend on population size
e.g. competition, food and disease
density independent limiting factors
-affect all populations in similar way regardless of population size
-e.g. hurricanes or wild fire
human influence on ecosystems
-humans take resources from biosphere
-as human population grows so does the resources we take for food medicine and shelter
-the waste we create can also effect organisms
