community development: successionani_mardiastuti.staff.ipb.ac.id/files/2011/10/... · gleason •...
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Community Development:Succession
Ani Mardiastuti
ApproachApproach
• Observational• Experimental
Community PatternsCommunity Patterns
• Species diversity: richness abundanceSpecies diversity: richness, abundance
• Spatial structure: distribution
i i• Association
• Disturbance and stability
Clements and Gleason: i d th t f itisuccession and the nature of communities
plant communities
Frederic Clements (1916) Henry Gleason (1917)
ClementsClements
• Communities superorganisms
• Communities follow a very specific sequence y p qof stages in terms of nutrient cycling, species diversity, and biomass
• There is a single “climax” community self‐perpetuating p p g
• Climax communities tightly integrated as the result of biotic interactions between species
Clementsian ModelClementsian Model
• A Clementsian community: a group of species C e e ts a co u ty: a g oup o spec esthat strongly interact with one another
• Clementsian community is a tightly integrated y g y ggroup of species that bear various causal relations between its component species
• The community forms an individual like that of a multi‐cellular organismTh Cl t i d l f di t bl• The Clementsian model argues for a predictable, orderly process which culminates in a stable climatic climaxclimatic climax
GleasonGleason
• Communities individualisticCommunities individualistic
• Succession results from individual species, physiological requirements and local climaticphysiological requirements and local climatic conditions
Th i fi l li i• There is no final climax community
• Communities continually changing and non‐equilibrial
Gleasonian ModelGleasonian Model
• The Gleasonian model is more complexThe Gleasonian model is more complex
• Interactions between the physical environmentenvironment
• Population‐level interactions
• Continuous change in vegetation
• Multiple steady states exist in ecosystem p y ydynamics
SummarySummary
Our LectureOur Lecture
• Patterns• Patterns• Process• Process
Community Development:
• Defined as the transition in species
Ecological succession• Defined as the transition in species
composition over ecological time• Plants and animals appear and graduallyPlants and animals appear and gradually
alter their environment as they carry on their normal activities.
• The accumulation of waste, dead organic matter, and abiotic factors such as light and , gwater availability further alters the community.
Community Development:Ecological succession
1. Primary succession• Occurs in an area not previously inhabited• Areas that have been completely devastated
by disturbance
2. Secondary succession• Occurs where there is a pre‐existingOccurs where there is a pre‐existing
community and well‐formed soil
Mount St. Helens Eruption in 1980Five explosive eruptions of Mount St Helens i 1980 i d h 6 10 il iin 1980 sent pumice and ash 6‐10 miles into the air.
The Aftermath of Mount St. Helens Eruption
These trees were blown down by a lateral blast. This is an example of where the process of primary succession will begin to bring new life
Primary SuccessionPrimary Succession• Occurs on essentially
lif l t ilifeless terrain– Volcanic eruptions– Retreat of glaciers– May take hundreds to
thousands of years• The first group of
iorganisms to appear1. Autotrophic bacteria2. Lichens
Lichens are a symbiotic relationship between Algae and F i Th t id th t3. Mosses (organisms that
reproduce by spores)4. Grasses, ferns, shrubs,
pine trees
Fungi. They secrete acid that turns rock into soil. Once the soil is established, plants can l ipine trees colonize
Primary Succession
Iceland is a “new” country emerging f b th th t i dfrom both the recent ice age and frequent volcanic eruptions
Primary S i i
Bogs• Algae carried in by birds and
Succession in Ponds and Lakes
g ythe wind
• They die and fall to the bottom contributing to the organic matter• In the Northern US,
many ponds and lakes are were left behind
matter.• Duckweeds form at the edges• When nutrients, oxygen, pH,
and temperatures are lowby the receding glaciers (10,000ybp)
• Many ponds become
and temperatures are low• Peat mosses take over,
forming a thick mat.• Woody shrubs and carnivorousMany ponds become
bogs.– have no streams
drainage so they are
Woody shrubs and carnivorous plants grow on this substrate
drainage, so they are filled by precipitation
– Grow smaller every year because of ysuccession
Bogs are an example of Primary Succession
P tPeat moss
Duckweeds (mata lele) occur early in succession
• Under less acidic conditions, duckweeds are one of the 1st plants toare one of the 1st plants to grow
• Grass‐like sedges become established and form a mat
• Once a mat is formed• Once a mat is formed, bushes, shrubs and trees become established
Secondary Succession• Existing community has
been disturbedS il i i t t– Soil is intact
– Abandoned Agricultural fields:• Old field succession• Climax community can
become established afterbecome established after only decades
• Disturbance colonizers:d l t iweedy plant species
1. a high reproductive rate,2. good at dispersal
Old Field Succession
1st yearHorseweed
3rd‐18th yearYoung
70th‐100th
Pine toHardwood
i iCrabgrasspigweed
Pine forest
19th‐30th year
transition
100th year plus
2nd yearAstersCrab grass
19 30 yearMature pineForestUnderstory of Y h d d
100th year plusClimaxOak‐hickory forestCrab grass Young hardwoods