succession Flashcards
ecosystem
a more-or-less self-contained unit in ecology made up of biotic and abiotic factors
community
all the populations of different species living and interacting together in a particular area
succession
occurs as a result of changes to the environment causing the plant and animals species present to change
takes place in a number of stages, known as seral stage
types of succession
primary and secondary
primary succession
occurs on an area of land that has been newly formed/exposed, such as bare rock
begins in a place without any soil or organic material present, e.g. sides of volcanoes, landslides
starts with the arrival of living things such as lichens, that do not need soil to survive
pioneer species
lichen
not a single organism
stable symbiotic association between a fungus and algae
algae photosynthesis
fungus provide protection and prevent lichens drying out while anchoring it to rock
sexual/asexual reproduction
what are the features of marram grass that enables it to be a pioneer species
deep roots
tolerates salty environment
features of pioneer species
asexual reproduction , fast population growth
vast quantities of wind-dispersed seeds or spores to reach isolated destinations
rapid germination of seeds
ability to photosynthesise
ability to fi nitrogen from atmosphere
tolerance to extreme conditions
primary succession - intermediate community
lichens weather the rock and a small amount of soil forms
rain and wind also erode rock into smaller pieces
when lichens die, they decompose, adding organic matter to the rock to make soil (humus= organic content of soil)
may alter environment by making it, less suitable for existing species, more suitable for other species with different adaptations
after lichens, simple plants can grow in the new soil
secondary colonisers : moss
tertiary colonisers : ferns
soil layer thickens, grasses wildflowers and other plants begin to take over
small animal species may also arrive
plants die, contribute to more nutrients to soil
shurbs and trees can survive
insects, small birds and mammals have begun to move in
climax community
a community in which populations of plants/animals remain stable and exist in balance with each other and their environment
final seral stage of succession, remaining relatively unchanged until destroyed by an event such as fire/human interference
show very little change
usually a few dominant plants
secondary succession
occurs on an area of lang where soil is present but contains no plant or animals species
e.g. bare earth after forest fire
occurs much faster than primary succession
animal succession
primary consumers colonise an area, consume and shelter in mosses and lichens
move in from neighbouring areas
much slower than plant succession
secondary consumers arrive once a suitable food source has been established and existing plant cover will provide them with suitable habits
eventually larger organisms, mammals will colonise area when biotic conditions are favourable
deflected succession
human activities halt natural flow of succession, preventing ecosystem from reaching a climax community
plagioclimax
community that only remains stable bc of human activities prevent succession
