Life Processes in the Biosphere

• Low temperature A • High temperature A • Low light levels A • Water turbulence A • Food B • Reproduction B • Symbiosis B

The range of abiotic factors an organism can survive within.

A relationship where both species benefit e.g. crocodile gets teeth cleaned by a bird, bird gets food.

Where a community changes over time in an area containing no vegetation or soil (bare rock).

Where a community changes on a previously colonised but disturbed area.

A stable community where no further succession occurs.

1) Pioneer species colonise. 2) Change abiotic conditions over time, increase dead organic matter. 3) New colonisers appear and out-compete pioneer species (die out). 4) Abiotic factors become stable, adaptations based more on biotic factors. 5) new species continuously colonise, thrive and die until climax community is reached. - Changes in plant species diversity, increases food type abailable, tall vegetation decreases light levels etc.

Similar to lithosere but succession occurs in water first before becoming dry land.

The succession/colonisation of an area of sand.

Where human activity has prevented the ecosystem developing further (deflected succession).

Young tree stems are cut near ground level as many trees will regrow from the stump.

Upper branches are removed to form dense foliage above - often used to maintain trees at a particular height.

1) Lag phase - pop. becomes established. 2) Logarithmic phase - rapid population growth, little environmental resistance. 3) Slow growth - intraspecific competition/disease/food. 4) Stable, fluctuating phase - density-dependent factors control pop. size. 5) Maximum number the land can sustain - carrying capacity.

r-selected = High growth rates, offspring have low survival rates, short lifespan. K-selected = live close to carrying capacity, few offspring, high chance of surviving to adulthood, long lifespans.

• Introduction of an invasive species. • Loss of indigenous predator = prey are unregulated. • Breeding rate of endangered is low so captive breeding needed. NOT CULLING - SUPPLEMENTING POPULATION.