Changes in ecosystems Flashcards
What is succession?
the process by which communities of organisms colonising an area change over time
What is a climax community?
a self-sustaining community with relatively constant biodiversity and species range. it is the most productive group of organisms that a given environment can support long term
What is a climatic climax community?
the only climax community possible in a given climate
What is a plagioclimax?
a climax community that is at least in part the result of human intervention
What are the steps of primary succession?
(starts on an area with no organisms e.g. bare rock)
- pioneer species colonise habitat and break up rock
- organic material build up in broken rock - beginning of soil
- habitat conditions change
- new species move in - change conditions further, increasing organic matter in soil (can now hold water)
- more species move in until dominant species is found
- community dominated by trees is reached - a stable climax community
What are the steps of secondary succession?
(recolonisation of a previous destroyed ecosystem)
- dormant seeds in seed banks in soil, or seeds brought by wind or animals begin to grow
- pioneer species grow rapidly - have short life cycle and abundant seed production, so dominate quickly, changing the soil
[primary succession continues]
Effect of light on populations
plants dependent on light for photosynthesis
animals affected by distribution of food patterns, seasonal light affects reproductive patterns
in low light areas:
- plants have more chlorophyll, different ratios of photosynthetic pigments
Effect of temperature on populations
reproduction doesn’t occur above/below certain temperatures
affects rate of enzyme controlled reactions in plants
Effect of wind and water currents on populations
wind increases water loss from body and cooling - adds to environmental stress
only few species can survive strong winds
organisms have to flow with current, be strong swimmer, be able to attach to surfaces and resist water force
currents mainly damaging when there’s a sudden increases e.g. flooding
Effect of water availability on populations
water vital for living organisms
if water stress too server - organisms die unless they have special adaptations e.g. camels, kangaroos, cacti
increase in water - changes in habitat e.g. increase in population
Effect of oxygen availability on populations
cold, fast flowing water has sufficient oxygen. if temp rises or becomes still then oxygen content drops
soil is aerated so lots of oxygen. waterlogged soil can have less and plants will die
Effect of edaphic factors on populations
relate to structure and mineral content of soil
soils with sand - loose structure, easily warmed but leaching can happen -less minerals get to plant
Effect of predation on populations
prey predator populations oscillate in a repeating cycle
- prey population increase, predator population increase
- prey population decrease, predator population decrease
Effect of finding a mate on populations
if a single seed is dispersed in a new area and germinates, grows, survives - unlikely to become permanent resident unless asexual respiration
animals- must be a male and female mate
Effect of territorial behaviour on populations
territory is area defended by another animal
mainly used to make sure breeding pair has enough resources to raise young
