Download Worksheet - Rudds Classroom

Name: _____________________________________________
Ecosystem Balance
Environmental Science
E2
Ecological Sucession
Organisms _______________ the environments in which they live
• Some changes are ______________________
• ____________________ help form soil by breaking down rocks
• Some changes are ________________________
• Species can alter environment so that a niche ______________________
• Replaced by new niches to which ________________________________ are better adapted
• Cause their own _______________________
Other ___________________ can also change the environment
• Forest _____________, volcanic eruptions, earthquakes, __________________
As environments change, the ______________________ living in that environment changes
• In many cases, different communities follow one another in a definite __________________
Primary Succession
The ____________________ of communities forming in an originally _______________ habitat
• On ______________ after it has cooled and hardened
• Bare ______________ exposed by a retreating glacier
Primary Succession is an _________________ process
First – _________________________ by new organisms & formation of _______
• Rocks are colonized by ______________________ – a fungus and an alga
living in a _______________________ relationship
• Lichens secrete ____________ that _______________________ the rock & form organic material
• Rocks are also broken down by ___________________________ caused by wind, rain, and frost
• The lichen and weather form _______________
Next – after soil has formed, __________________ and small _______________ begin to grow
• Seeds are carried to the habitat by _____________ or ___________________
• Plant ______________ continue to break down rocks
• Dead __________________ also help soil formation
• In time, plants grow dense and tall enough to ______________ the sun from the lichens
• The lichen community is ___________________ by the grass community
Next – grass community survives for many ____________________________
• Makes the soil _________________ and more fertile
• Allows for the growth of _____________________ plants and __________
with deeper roots
• In time this foliage becomes tall and dense enough to form a ___________________ that blocks
the sun from grasses
Next – when the soil is deep enough, _____________ or other trees with _______________________
move in
• As trees move in, the community _________________ again
• Trees shade out the ______________ and grasses
Finally – ___________________ and __________________ trees begin to grow and replace the pines
• Hardwood forest is the ________________ stage of succession
• It changes very ________________ over time
• Climax community – A community that _________________ undergo further _______________
Ecosystem Balance
_________________
community
E2
_________________
community
Secondary Succession
Primary succession occurs _____________ on freshly exposed rock or places where _______ the
organisms and soil have been removed or destroyed
• However, most disturbances are _________ that drastic
Secondary succession – occurs where a disturbance eliminates most _______________________ but
does ___________ destroy the ______________
• Example: A forest fire will ______________ trees and plants, but leave the soil
• Living things can _____________________________ areas created by these types of disturbances
• Resembles the ______________ stages of primary succession
• Usually begins at the _________________ or ______________ stage
Incomplete Succession
Many habitats never develop ____________________ communities
• It takes several _________________________ years to complete the process of succession
• If disturbances occur more _______________________ than that, the area ___________________
complete the succession
• Example: A Grasslands Habitat
• ____________________ or ___________________ disturbances kill seedling shrubs and trees
• Succession _______________ progresses _____________ the grass community
Aquatic Succession
Succession also occurs in ___________________ habitats
• Newly formed lake where water has ____________ nutrients
• _____________ and other water plants grow near the _____________
• Organic matter begins to _________________ in the lake
• Provides _____________________ for more plants
• ____________________ accumulates on the bottom of the lake
• More _____________________ can survive
• Water plants cover the ___________________ of the lake
• Lake fills with sediment and becomes a ________________
• _______________ plants colonize the marsh
• Marsh becomes a ______________________
• Meadow ultimately turns into a _____________________
Ecosystem Balance
E2
Section Review
1. How does primary succession differ from secondary succession?
2. What is a climax community?
3. Suppose humans put out all the fires in a large area of grassland over a period of 100 years.
What would happen to the grassland community?
4. Would you expect primary succession or secondary succession to occur in an area after a
tsunami destroyed a coastal community? Explain
5. List, in order, the 6 communities in primary succession from the pioneer community to the
climax community
6. Primary succession can occur in which of the following habitats?
a. old-growth forest
b. new pond
c. corn field
d. cooled lava field
7. A defining characteristic of a climax community is that it is essentially
a. grassy
b. forested
c. stable
d. sedimented
8. The first organisms to colonize a newly formed lifeless habitat are part of
a. mature communities
b. primary succession
c. secondary succession
d. a shoreline ecosystem
9. Lichens are important to an ecosystem because they
a. help form soil
b. prevent trees from growing
c. are unstable
d. replace older communities
10 A mature, stable, and diverse ecosystem is called
a. a habitat
b. primary forest
c. successful
d. climax community
11. Through aquatic succession, a clear lake may eventually become
a. an aquifer
b. a meadow
c. barren rock
d. an ocean
12. Which type of disturbance would most likely result in secondary succession
a. glacier retreats leaving barren rock
b. a volcanic eruption
c. rainfall creates a new lake at the top of a mountain
d. an earthquake
13 Aquatic succession typically begins
a. in the middle of a lake
b. at the bottom of a lake
c. at the shoreline of a lake
d. on the surface of a lake