LG: How Do Ecosystems Recover from a Disturbance?

January 2013 Regents food web question

ECOLOGICAL SUCCESSION

is the series of changes that occur

in an ecosystem over time.

It can occur on LAND or

in AQUATIC ecosystems.

There are TWO types of

succession on LAND.

1. PRIMARY

2. SECONDARY

PRIMARY SUCCESSION

is the sequence of

communities that form in an

originally lifeless habitat.

Primary succession occurs

on BARE ROCK.

What could occur to give us

bare rock in a place that had

already had plants living?

Primary Succession

The first organisms (pioneer organism) to appear are LICHENS.

Lichen is a FUNGUS and ALGAE living

in a MUTUALISTIC relationship.

The first living things to grow successfully on a newly formed sand dune are known asa. saprophytesb. pioneer organismsc. carnivorous plantsd. heterotrophs

Lichens grow on

bare rock and break

down (weather) the rock

to form a thin layer of soil.

Primary Succession

The lichen make up a

PIONEER COMMUNITY.

A pioneer community is

the first one in a new

habitat.

Base your answer on the diagram below, which shows the sequence of plant communities that have occupied land that was left barren 300 years ago, and on your knowledge of biology.

Which plant species represent pioneer organisms?a. broomsedge and pine seedlingsb. ragweed and asterc. crabgrass and horseweedd. oak and hickory trees

Lichens & Mosses

Crevice Community

2.Lichens & mosses (pioneer)3.Grasses and shrubs4.Trees (climax community)

1.Bare rock

THE STAGES OF PRIMARY

SUCCESSION

Base your answer on the diagrams below of four stages of a biological process and on your knowledge of biology.

What would most likely be the predominant life form found in stage I?a. fernsb. tracheophytesc. mushroomsd. pioneer species

A Typical New York

State Succession

A slab of bare rock is covered with lichens. In time, mosses cover the rock, followed by grasses, and finally by small shrubs and tree saplings. In this example, the lichens represent

a. a climax communityb. a dominant speciesc. secondary consumersd. pioneer organisms

A CLIMAX COMMUNITY

• is a diverse and mature community

that does not go through more

succession.

•should be able to withstand disruption

better than earlier ecosystems,

causing succession to stop

ECOSYSTEM STABILITY

•During succession, the stability of an ecosystem changes

•Stability is the ability of an ecosystem to remain constant in the face of disturbance

Which organism is one of the first autotrophs to appear in this succession?

a. frogb. aquatic plantc. treed. fish

•As the diversity of an ecosystem

increases, the stability increases

•A more diverse ecosystem contains a

more complex food web

oThis means an organism is more

likely to find an alternate food

source if need be.

Changes in an ecosystem over a long period of time are shown in the diagram below.

These changes will most likely lead to aa. stable ecosystem that can last for many yearsb. loss of heterotrophs that cannot be recoveredc. long-term rise in environmental temperaturesd. forest consisting of only producers and decomposers

Base your answer on the diagram below, which shows the sequence of plant communities that have occupied land that was left barren 300 years ago, and on your knowledge of biology.

Dominant plant species in the climax community includea. pine treesb. hickory treesc. mossesd. lichens

www.educeth.ch/stromboli/ perm/msh/life-en.html

The diagram below shows various ecological communities that occupied an area over a period of 300 years.

Which statement best describes the diagram?a. Community A is the most stable community.b. Community B replaced community C after a period of 100 years.c. Community C developed into community A after a period of 75 years.d. Community D modified the environment, making it more suitable for community E

SECONDARY SUCCESSION

occurs where an existing

community has been

cleared by some

disturbance but the soil

is not destroyed.

Secondary Succession

DEFORESTATION and

FIRE are

disturbances

that will clear

the existing

community but

not destroy

the soil.

Secondary Succession

Over a long period of time, the stages represented in the diagram below were each present in a particular ecosystem.

After a forest fire, what is the most likely order in which these stages appeared?a. D C A Bb. B D C Ac. A B C Dd. B C D A

Aquatic SuccessionAquatic HABITATS are in

WATER.

Over long periods of time

ponds fill in slowly with

sediments and plants.

Aquatic Succession

The ponds fill

in over time

to become

a marsh,

a meadow or

eventually

a forest.

Which statement best describes one of the stages represented in the diagram below?

a. The mature forest will most likely be stable over a long period of time.b. If all the weeds and grasses are destroyed, the number of carnivores will increase.c. As the population of the shrubs increases, it will be held in check by the mature forest community.d. The young forest community will invade and take over the mature forest community.