Succession

The gradual, sequential regrowth of a species in an area due to changing

conditions

Succession

• PRIMARY succession– Development of a community in an area that has

not supported life before.• Requires the building of soil by PIONEER PLANTS

– Small fast-growing & fast-reproducing plants– Lichen, moss, crabgrass, plankton

Primary succession

• Seral stages– Developmental stages of an environment– Ecological communities that succeed one

another in the biotic development of an area– Species will eventually be replaced by

successive species based on conditions such as

Soil quantitySoil type

SunlightWater

Seral stages

• Can be determined by an index species• Index species Definition

– Species that are used as a reference point to indicate relative placement in an ecosystem

Primary succession

• Climax Community– Will be established eventually– Community will prevail unless the area is

disturbed again– Hardwood trees (maple, beech, birch)

Examples of Primary Succession

• Bare Rock Succession• Sand Dune Succession• Pond/Lake Succession

Bare rock succession

• Pioneer Plants: – Lichens

Help break down rocks Adds humus for

new soil building What’s humus?

Substance that provides nutrientsIncreases the ability of soil to retain H2O

Bare rock succession

• Seral stages: – Mosses/fern– Grasses/weeds– Bushes– Softwood trees

• Each stage paves the way for the next stage

Bare rock succession

• Climax community– Hardwood trees

• Species of plant remain constant for a long period of time until a disturbance occurs

Bare rocks

Mosses, ferns

Grasses, weeds

Bushes

Hardwood treesSoftwood

trees

Lichen

Sand dune succession

• Pioneer plants:– Beach grass

• Roots stabilize the sand• Humus is added

to the foredune– An area directly

behind the beach

Sand dune succession

• Seral stages– Cottonwood– Pines– Oaks

• Continue to add humus and shade to the soil

Sand dune succession

• Climax community– Beech or maple

succession

Pond/lake succession

• Pioneer plants/organisms– Microscopic plants and animals

• Phytoplankton - producers • Zooplankton - consumers

• Found in open water

• Humus is added and soil develops

Pond/lake succession – Seral stages

• Rooted submerged zone – Closer to the shore – Light penetrates all the way to the bottom so

young plants can grow– Algae/Kelp

Pond/lake succession – Seral stages

• Rooted floating zone– Rooted in the bottom and leaves float on the

surface – Water lilies

• Emergent zone – Very shallow water – Rooted in the bottom and

extend through the surface – Cattails

Pond/lake succession

• Climax community– Land

Process of lake/pond succession• As the plants die and as sediment washes in

from the surrounding land the lake (pond) fills-in

• First the open water zone disappear• Then the rooted submerged zone, • Then the rooted floating zone, • Then the emergent zone

Process of lake/pond succession

• Succession of an open field now takes place (grasses and weeds, bushes, softwood trees, finally hardwood trees)

• Climax community will depend on the biome the lake (pond) was in.

Secondary succession

• Sequential replacement of species that follows the disruption of an EXISTING community

Secondary succession

• Pioneer species– Grasses– Weeds– Plants must be adapted to hot, dry conditions

Secondary succession

• Seral stages– Bushes– Softwood trees– Adds humus & moisture to the soil– Then later, replaced by a larger species

Secondary succession

• Climax community– Hardwood trees

Ecosystem

A system formed by the interaction of a community of organisms with

their environment

Ecological Relationships

• Trophic Level– Any class of organisms that occupy the same

position in a food chain– Examples

Energy Flow

• Producers have the most energy.• As an organism eats the next, available energy

decreases.• Only 10% is passed on to the next trophic

level. (Ten Percent Law)• What happens to the other 90%?

– Transferred as heat to the environment

Pyramid of Energy

• A measure of theamount of energyavailable in eachtrophic level

Ecosystem Recycling

• All molecules are recycled naturally in the environment through a biogeochemical cycle.

• Biogeochemical cycle– Movement of elements through various

compartments (at least one being biological).– Water cycle– Carbon/oxygen cycle– Nitrogen cycle

Water Cycle

• Movement of water through various reservoirs• Precipitation

– Water falling from the atmosphere to the ground• Transpiration

– Water entering the atmosphere from plants• Respiration

– Water entering the atmosphere from animals• Evaporation

– Water entering the atmosphere through a phase change (liquid to gas)

Water Cycle

• Absorption– Water taken in by a plant

• Urination– Water added to the ground by an animal

• Runoff/Seepage– Excess water entering land or another body of water

• Aquifer/Groundwater– Underground water stored in porous rocks

Respiration

Transpiration

Absorption

UrinationRun-off

Precipitation

Evaporation

Aquifer

Carbon/Oxygen Cycle

• Movement of organic compounds through various reservoirs.

• Based on concepts of photosynthesis and cellular respiration

• Photosynthesis– Autotrophs used CO2 found in the atmosphere and

convert it into an organic compound C6H12O6

Carbon/Oxygen Cycle

• Respiration– Hetertrophs consume the glucose and release carbon

compounds in the form of CO2 wastes• Decomposition

– When detritivores feed off of the remains of dead organisms

• Fossil fuel– Formed from years of high temperature and pressure of

decaying, organic matter• Combustion

– The burning of organic matter

Carbon dioxide

Photosynthesis

Glucose

DecompositionFossil Fuels

Combustion

Respiration

Nitrogen Cycle

• Movement of nitrogen-containing compounds (proteins, nucleic acids, atmospheric nitrogen, urine, ammonia, nitrates and nitrites.)

• Cycle could not exist if it wasn’t for BACTERIA• Ammonification

– Decomposition– When detritivores feed off the remains of dead

organisms and convert protein and nucleic acids into ammonia

Nitrogen Cycle

• Nitrification– When bacteria convert ammonia into nitrates (NO3) and

nitrites (NO2)• Absorption

– When plants take up nitrates and form amino acids which consumers will acquire as protein

• Denitrification– When bacteria break down nitrates and produce nitrogen

gas

Nitrogen Cycle

• Nitrogen Fixation

– When bacteria found on special plants (legumes – beans, peas, alfalfa) converts atmospheric nitrogen into ammonia.

– Lightning can also perform this process.

Atmospheric Nitrogen

Nitrogen Fixation

Lightning

Feeding

NH4

AmmonificationNO3-

Absorption

Nitrates (NO3-)and Atmospheric Nitrogen (N2) used by plants