Download Succession - New ESS Course

Zonation and
Succession
IB Syllabus: 2.4
Vocabulary
 Climax Community
 Community
 Evolution
 K strategists
 R strategists
 Sere
 Succession
 Zonation
Community
 A group of populations interacting in a particular area
 The marine life of Hoi Ha Wan reserve
 The forests along Shing Mun Valley
Communities Change
 Ecological Succession: the change of species composition
for a specified area over time.

2 Types depending on start point
 Primary succession: gradual establishment of biological
communities on lifeless ground
 Secondary succession: reestablishment of biotic
communities in an area where they already existed
 Zonation: the change of species composition spatially within
at a certain point of time
Zonation
 Horizontal bands or zones of animals and organisms
 Differing plant and animal communities as you go up
a mountain
 Differing plant and sea life communities as you go
deeper from shore.
 Created by abiotic and biotic factors
 Change in these factors is called an environmental
gradient
 In a rocky intertidal zone these would be
 Exposure (tides), salinity, competition, hydraulic
action
Source: http://hoopmanscience.pbworks.com
Altitudinal Zonation
 Occurs due to changes caused by altitude during an
identified period of time.
 Every 100m in altitude = one degree temperature
decrease.
 Drier air caused by cooler temperatures.
 Changes in biotic communities caused by abiotic
factors.
Measuring changes along an
environmental gradient?
 Change in benthic (bottom) community of rocky
intertidal with increased depth
 Gradient in moisture or drying
 Use modified quadrat method
 run transect into deeper water
 At set depths place quadrat and sample organisms
 Do repeated transects along your sample area
 Calculate differences in communities with depth
1. Primary Succession
 Begins in area with no soil on land, no sediment in water
 Cooled lava, bare rock from erosion, new ponds, roads
Img source: http://w3.marietta.edu/~biol/biomes/images/succession/acadia2.jpg
Exposed
Lichens
rocks and mosses
Small herbs
and shrubs
Heath mat
Time
Jack pine,
black spruce,
and aspen
Balsam fir,
paper birch, and
white spruce
climax community
Pioneer Communities
 Lichens and Mosses
 Survive on nutrients in
dust and rock
 Start soil formation
 Trap small particles
 Produce organic material
through photosynthesis
 Chemically weathers the
rock
 Patches of soil form
Exposed
Lichens
rocks and mosses
Small herbs
and shrubs
Heath mat
Time
Jack pine,
black spruce,
and aspen
Balsam fir,
paper birch, and
white spruce
climax community
Seral Stages: Early Successional Plant
Species
 Small perennial grasses
and herbs colonize, from
wind blown seeds
1. Small plants grow close
to the ground
2. R-strategists immigrate
3. Short lived sere
4. Break down of rock
Exposed
Lichens
rocks and mosses
Small herbs
and shrubs
Heath mat
Time
Jack pine,
black spruce,
and aspen
Balsam fir,
paper birch, and
white spruce
climax community
Mid to Late Succession
 After 100’s of years,
deep soil forms
 Holds moisture &
nutrients
1.
Shrubs then trees
colonize
2.
Trees create shade
3.
Shade tolerant species
establish
Seral stages
 A seral community (or sere) is an intermediate stage
found in ecological succession in an ecosystem
advancing towards its climax community.
 An example of seral communities in secondary
succession is a recently exhausted cropland in tropical
rainforests.
 during the first two years, grasses, herbs and softwood saplings
will be abundant
 After many more years the saplings will start to form a canopy
and shade tolerant shrubs will start to develop.
 Eventually hardwood epiphites like ficus and banyan will develop
in tandem with lianas to form a thick canopy.
 Each of these stages can be referred to as a seral
community.
Climax community
 Characterized by K-selected species
 Climax community structure is in stable equilibrium for each
area
End Result = Complex Community
 Complex community mix of well established trees, shrubs
and a few grasses
 Disturbance may change the structure
 Fire, Flood, Severe erosion, Tree cutting, Climate
change, Grazing, habitat destruction
 Specific successional stage is dependent on the
frequency of disturbance
 Silviculture and intercrops may maintain the
 plagio-climax sere.
Disturbance and Diversity
 Disturbance = any change in conditions which disrupts
ecosystem or community structure
 Catastrophic or Gradual
 Disturbance eliminates strong competitors allowing others a
chance
 Promotes diversity
 Intermediate disturbance  greatest diversity
Secondary Succession
 Begins when natural community is disturbed BUT
soil & sediment remains
 Abandoned farms, burned forests, polluted streams
 New vegetation can germinate from the seed bank
 In both cases succession focuses on vegetation
changes
What changes occur through
Succession?
Diversity
1.
 Starts very low in harsh conditions few species tolerate
– r selected species types
 Middle succession mix of various species types – most
diverse (role of disturbance)
 Climax – k selected species strong competitors
dominate
Mineral Cycling
2.
•
Pioneer, physical breakdown & make organic, Later
processing increase – cycles expand
3. Gross productivity changes (total photosynthesis)
•
Pioneer = Low density of producers at first
•
Middle & climax = high  lots of producers and consumers
4. Net Productivity (G – R = N)
•
Pioneer = little respiration so Net is large  system is growing,
biomass accumulating
•
Middle & climax = respiration increases dramatically  N
approaches zero (P:R = 1)
5. Energy flow
•
# of trophic levels increases over time
•
Energy lost as heat increases with more transfers
Table 8-1 Ecosystem Characteristics at Immature and Mature Stages of Ecological Succession
Characteristic
Ecosystem Structure
Plant size
Species diversity
Trophic structure
Ecological niches
Community organization
(number of interconnecting
links)
Table 8-1
Page 158
Immature Ecosystem
(Early Successional Stage)
Immature Ecosystem
(Late Successional Stage)
Small
Large
Low
High
Mostly producers, few decomposers
Mixture of producers, consumers,
and decomposers
Few, mostly generalized
Many, mostly specialized
Low
High
Ecosystem Function
Biomass
Net primary productivity
Food chains and webs
Low
High
High
Low
Simple, mostly plant
with few decomposers
herbivore
Complex, dominated by
decomposers
Efficiency of nutrient recycling Low
High
Efficiency of energy use
High
Low
Factors in Succession
Facilitation
1.
•
One species makes an area suitable for another in a
different niche
•
Legumes add nitrogen so other plants thrive
Inhibition
2.
•
Early species hinder establishment and growth of later
species  more disturbance needed to continue
•
Allelopathy by plants is an example
Tolerance
3.
•
Late successors not affected by earlier ones
•
Explains mixture of species in Climax Communities
Predictability of
Succession
 Generally predictable end of succession is a Climax
community
 Only real rules are Continuous change, Instability, and
unpredictability
 Ever changing mosaic of patches in different
successional stages
 No real progression to an end, rather we see a
reflection of an ongoing battle for resources and
reproductive advantage
Aquatic
Succession
Ecological Stability & Sustainability
 Maintained by constant dynamic change
 Positive and Negative feedback systems
 Community may change but you will still
recognize it as a particular type of community
 Inertia = The ability of a living system to resist
disturbance
 Resilience = the ability of a system to bounce back
after a disturbance
Grizzly
bear
NORTH
AMERICA
More than 60% of the
Pacific Northwest
coastal forest has
been cut down
40% of North America’s
range and cropland
has lost productivity California
condor
Hawaiian
monk seal
Eastern
cougar
Spotted
owl
Blackfooted Florida
ferret panther
Mangroves
cleared
in Equador for
shrimp ponds
Endangered species
6.0 or more children
per woman
Fish catch in the north-west Atlantic has fallen
42% since its peak in 1973
Chesapeake Bay is overfished and polluted
Golden
toad
Coral reef destruction
Every year 14,000
square kilometers of
rain forest is destroyed
in the Amazon Basin
Columbia has
lost one-third of
its forest
PACIFIC
OCEAN
Vanishing biodiversity
Humpback
whale
Manatee
Much of Everglades National Park has dried out
and lost 90% of its wading birds
Kemp’s
ridley
turtle
Half of the forest
in Honduras and
Nicaragua has
disappeared
Environmental degradation
St. Lawrence
beluga whale
Black lion
tamarin
SOUTH
AMERICA
Southern
Chile’s rain
forest is
threatened
Little of Brazil’s
Atlantic forest
remains
ATLANTIC
OCEAN
Poland is one of
the world’s most
polluted countries
Imperial eagle
640,000 square kilometers
south of the Sahara have
turned to desert since 1940
EUROPE
Mediterranean
Many parts of
former Soviet Union
ASIA
are polluted with
industrial and radioactive waste
Central Asia from the
Middle East to China
has lost 72% of range Giant
and cropland
panda
Area of
Aral Sea has
Shrunk 46%
Snow leopard
Japanese timber imports
are responsible for much
of the world’s tropical
deforestation
Saudi
Arabia
Deforestation in the Himalaya
Asian
causes flooding in Bangladesh
Liberia
elephant
Oman
Kouprey
Eritrea
Mali AFRICA
Yemen
90% of the coral reefs
India and
are threatened in the
Burkina Niger
Ethiopia
Sri Lanka
Philippines. All virgin
Faso
Benin Chad Golden
have almost
forest will be gone
Sierra
tamarin
no
rain
Nigeria
by 2010
Leone
forest left
Togo
Congo Uganda
Sao Tome Rwanda
Somalia
In peninsular Malaysia
Queen Alexandra’s
68% of the
Burundi
almost all forests have
Birdwing butterfly
Congo’s
Angola
been cut
rain forest
Indonesia’s
is slated
Zambia
coral reefs are
Nail-tailed
for cleaning
INDIAN OCEAN threatened
wallaby
and
Aye-aye
Fish catches in
mangrove AUSTALIA
Black
Southeast Atlantic
forests
Madagascar has
have dropped by more rhinoceros
Much of
have been
lost 66% of its
than 50% since 1973
Australia’s
cut
in
half
tropical forest
range and
cropland
have turned
to desert
Blue whale
A thinning of the ozone layer occurs
over Antarctica during summer
ANTARCTICA
Hydrosere
 A hydrosere is simply a succession which starts in
water. A wetland, which is a transitional area between
open freshwater and dry land, provides a good example
of this and is an excellent place to see several stages of
a hydrosere at the same time.
 In time, an area of open freshwater such as a lake, will
naturally dry out, ultimately becoming woodland. During
this process, a range of different habitats such as
swamp and marsh will succeed each other.
Hydrosere
Halosere

The term Halosere is an ecological term which describes succession in a
saline environment. An example of a halosere would be a salt marsh.

In river estuaries, large amounts of silt are deposited by the ebbing tides
and inflowing rivers.

The earliest plant colonizers are algae and eel grass which can tolerate
submergence by the tide for most of the 12-hour cycle and which trap
mud, causing it to accumulate. Two other colonisers are salicornia and
spartina which are halophytes -i.e. plants that can tolerate saline
conditions. They grow on the inter-tidal mudflats with a maximum of 4
hours' and exposure to air every 12 hours.

Spartina has long roots enabling it to trap more mud than the initial
conlonizing plants and salicornia, and so on. In most places this becomes
dominant vegetation. The initial tidal flats receive new sediments daily,
are waterlogged to the exclusion of oxygen, and have a high pH value.

The sward zone, in contrast, is inhabited by plants that can only tolerate
a maximum of 4 hours submergence everyday (24 hours). The dominant
species here are sea lavender and other numerous types of grasses.
Halosere
Xerosere
 Xerosere is a plant succession which
occurs in conditions limited by water
availability or the different stages in a
xerarch succession.
 Xerarch succession of ecological
communities originated in extremely dry
situation such as sand deserts, sand dunes,
salt deserts, rock deserts etc.
 A xerosere may include lithoseres and
psammoseres.
Psammoseres
 In geography, a psammosere is a sand sere - an
environment of sand substratum on which
ecological succession occurs.
 In a typical succession on a sea-coast
psammosere, the organisms closest to the sea will
be salt tolerant species such as littoral algae and
glasswort. Progressing inland the succession is
likely to include meadow grass, sea purslane, and
sea lavender eventually grading into a typical nonmaritime terrestrial eco-system.
 www.sanddunes.20m.com/Evolution%20.htm
