lu5 ecological succession (final)

Question 1

SUCCESSION term

change in sp… struc…….
….. & …. components involved

Answer 1

• The observed process of change in the species structure of an ecological community over time.
• Ecological succession: The process of community development, through a series of intermediate successional stages leading to the “climax” community. Both abiotic and biotic components are involved in this process.

Question 2

examples of ecological succession

forest…… demolished building

Answer 2

• A forest could have been a shallow lake a thousand years ago.
• Mosses, shrubs and small trees cover the concrete of a demolished building.

Question 3

3 key reasons WHY does “ecological succession” occur?

Cl, Ph, Biotic

Answer 3

• Succession can start on a bare area OR a disturbed area.
• Bare areas are classified as rock and water.
• May be caused by several factors:

(i) Climate causes:
* Plants cannot adjust to the long variations in the
climate.
* The different climatic causes that changes the
vegetation:
- the wind may eliminate the previous vegetation
- drought – drying & killing of weaker species
- snow – killing the previous vegetation

(ii) Physiographic:
- erosion by water, wind & gravity
- deposition of soil
- emergence of barren land surfaces

(iii) Biotic:
- man destroying natural vegetation
- animals overgrazing etc.

Question 4

HOW does “ecological succession” occur?

formation of….habitat,, disturbance of existing community

Answer 4

1) formation of new, unoccupied habitat (e.g. a lava flow or a severe landslide) [primary succession]
2) by some form of disturbance of an existing community(e.g. forest fire, human
activities - logging/agricultural activities) [secondary succession]

Question 5

two types of succession:

Answer 5

1) primary succession
* Development begins on an area that has not been
previously occupied by a community, such as:
- a newly exposed rock or sand surface (no soil)
- a newly formed volcanic surfaces such as lava flow
- a newly exposed glacial tills
- a newly formed lake

2) secondary succession
* Begins in a place that already has soil and once the home of
living organisms.
* Occurs on previously occupied (vegetated) sites after
disturbance.
* Disturbance is defined as any process that results in the
removal (either partial or complete) of the existing vegetation
(community).

Question 6

Hydrosere succession:

PRAQFFRSSMWCF

Answer 6

Plant succession occurs in an area of freshwater

Phytoplankton → Rooted submerged hydrophytes → Free floating plants → Reed swamp stage → Sedge marsh/meadow stage → Woodland stage → Climax forest

Question 7

Example of succession in aquatic environment (Hydrosere - A Wetland Example of Succession in Action)

Answer 7

Open Freshwater → Submerged Plants → Swamp → Marsh → Alder/Willow → Climax Woodland

Question 8

5 differences on primary and secondary

where occur, region plant life got/not, presence soil-organic matter, pioneer community, time span-long/short

Answer 8

primary:
1. It occurs on a site previously unoccupied by a community.
2. The region has no plant life.
3. The region lacks soil and organic matter altogether.
4. It is very challenging for the pioneer community.
5. It takes very long, over 1000 years.

secondary:
1. It occurs on previously occupied (vegetated) sites after disturbance.
2. The region has some plant life (seeds, underground stems, etc.)
3. The region retains some soil and organic matter.
4. Surviving plants easily grow to form a pioneer community.
5. It takes short time, 50 – 200 years.

Question 9

Seasonal and cyclic succession

not dependent on disturbance; periodic changes arising from……. species interactions or…….. event

Answer 9

Unlike secondary succession, these types of vegetation change are not dependent on disturbance but are periodic changes arising from fluctuating species interactions or recurring event.

Question 10

Climax community or climatic vegetation

final/stable community in a sere
self………… eq………
no n…….an….ac……. of organic matter

Answer 10

• The final or stable community in a sere is the climax community or climatic vegetation.
• It is self-perpetuating and in equilibrium with the physical habitat.
• There is no net annual accumulation of organic matter in a climax community mostly.
• The annual production and use of energy is balanced in such a community.

Question 11

Characteristics of climax community

tolerance, balance, equilibrium

Answer 11

1. The vegetation is tolerant of environmental conditions.
2. wide diversity of species, a well-drained spatial structure, and complex food chains.
3. The climax ecosystem is balanced.
   - There is equilibrium between gross primary production and total respiration, between energy used from sunlight and energy released by decomposition, between uptake of nutrients from the soil and the return of nutrient by litter fall to the soil.
4. Individuals in the climax stage are replaced by others of thesame kind. Thus, the species composition maintains equilibrium.
5. It is an index of the climate of the area. The life or growth forms indicate the climatic type.