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Succession - Coggle Diagram
Succession
Communities
sum total of ALL POPULATIONS (species) in particular area
D:
biotic component
of ecosystem
involving interaction between
autotrophic + heterotrophic species
Ecosystems
D: community of different species which are interdependent + interact w/ each other
AND THEIR ABIOTIC ENVIRONMENT
community & its physical environment
Biotic (B) + Abiotic (A) components
abiotic components
rock type
climate
determine how species interact
in areas like
energy flow
nutrient & gas exchange
Succession
D: progressive series of changes
in composition of a community
of organism
over time
'community
development'
involves changes to:
community
(species present)
abiotic environment
Primary Succession
(SLOW)
where?
newly formed
barren substrates
not been previously colonised
e.g
lava fields (after volcanic eruption)
sudden appearance volcanic island
exposed rock @ base disused quarry
why?
exposed land (rock) provides
v. harsh + hostile environment for life
no soil present to support plants
brought about by action of organisms
modify physical environment
more suitable other species
how ?
1.
seral stage 1 -
PIONEER SPECIES
(lichens)
colonise 1st
can survive hostile conditions
can grow on bare rock - tolerate desiccation
modify environment
over time
degrade rock
help promote weathering (aided by climate)
forms embryonic soil
2. SOIL
initially accumulates in cracks in rock
lichens die + decompose
soil develops + stabilises - + nutrients added
can support next seral stage species = MOSSES
3.
community further develops
communities at each stage
help modify A environment
creating A env. necessary for next stage
e.g. lichens + mosses form embryonic soil
increasing mineral availability
needed for next species
end point =
CLIMAX COMMUNITY
D: stable end of succession which in equilibrium with environment
overview
pioneer species
lichens colonise bare rock
degrade rock, die + decompose - form soil
mosses
grow in thin soils in rock crevices
plants
(flowering + ferns) grow - in deeper soils (DS)
(from decomposition of pioneer species)
shrubs + small trees
(holly) - DS
diversity = HIGH - many species small ferns + flowering
larger trees
(oak+ash) - DS
outcompete smaller trees
diversity may reduce
climax community formed + soil reaches max depth
Climax Community
CLIMATIC climax
if CC determined by
climate
eg rainfall or temp
BIOTIC climax
if CC determined by
influence of other organisms
eg grazing
relatively unchanged for
LONG period of time
more complex communities, more stable
always be something that can survive wind/fire etc
in Britain
natural climax =
deciduous forest
modified climax =
grasslands
=
DISCLIMAX
developments
soil depth
soil fertility
plant biomass
plant
diversity
initially increases
A conditions become more
suitable for more species types
near CC
diversity decreases
fewer species survive in low light levels of woodland floor
due to tall tree canopy
species type
changes
pioneer species
good colonisers
bad competitors
∴ die out + replaced by more demanding plants
FEATURES
predictable
in pattern
pioneer species always b initial colonisers
CC develop in same conditions
abiotic environment
becomes
less hostile
soil forms
growth of plants = provides shelter for organisms in later stages
height + biomass
of
plants
increases
communities become
increasingly complex
more complex food webs
greater no. niches for animals
increased
biodiversity
later stage communities
more stable
than earlier stages
Secondary Succession
(FASTER, predictable, repeatable)
where?
on ground has previously been colonised
now available
after previous climax community damaged
why faster?
soil already formed
nutrients present
underground
root system
seeds present
in soil
soil organisms present in soil
nitrifying bacteria
detritivores
Climax Community
reached in much faster time
why community previously destroyed?
fire
flooding
wind damage
human interference
Differences to Primary
some species particularly adapted to
ecological niche (cleared woodland)
regenerate v rapidly
from seed in soil
colonise from
surrounding area
1° = not previously colonised
2° = area where community been removed
Similarities to
Primary
both involve change in species composition with time