Ecology 6.6

• Biologie
• Middelbare school
• vwo
• Leerjaar 3

Today's lesson

A bit of a review

Discuss 6.6 - Ecological succession

Which of the following is usually true about secondary consumers in an ecosystem?

1. They eat only plants
2. They are eaten by primary consumers
3. They are fewer in number than are primary consumers
4. They contain the greatest total biomass in the system

Which of the following best explains why there are seldom more than five trophic levels in a food chain?

1. Most carnivores function at more than one trophic level
2. Top carnivores are too few in number to hunt effectively
3. The ecosystem contains too much biomass
4. Energy is lost from each trophic level

Ecological succession

Pioneer community

Lichen

• is a composite organism that arises from algae living among filaments of multiple fungi species in a mutualistic relationship
• 6-8% of the earth is covered by lichen
• 20,000 different species
• reproduce asexually

Moss

• small, non-vascular flowerless plants that  dense green clumps or mats, often in damp or shady locations
• individual plants are usually composed of simple leaves that are generally only one cell thick
• do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores

Steps in succession

1. Pioneer species come in 
2. Through their existence they change the abiotic factors (add nutrients to ground, create shade, block wind etc)
3. This makes the environment suitable for other species to come in
4. These new species can outcompete the previous species making them dissapear from the system
5. This creates a follow up of species over time, because the population keep on changing the environment

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Climax community

Plant and animal species are constant

They are no longer replaced by other species

A high amount of biodiversity

Complex food web

What is the order of succession shown in this figure?

1. A, B, C, D
2. A, D, C, B
3. C, A, D, B
4. C, D, A, B

What type of succession is shown going from figure A to figure B?

1. Primary succession
2. Secondary succession
3. Intermediate succession
4. Deflected succession

Largest number of individuals of a population that the environment can support

1. carrying capacity
2. primary succession
3. limiting factor
4. density dependent factor

As succession progresses, animal species diversity increases due to the fact that

1. less soil is being created
2. food choices increase
3. precipitation rates stabilize
4. temperatures moderate

Scientists found, that over a period of 200 years, a mountain pond was transformed into a meadow. During that time, several communities of organisms were replaced by different communities. Which of these best explains why new communities were able to replace older communities?

1. The original species became extinct
2. Species in the older community died from old age
3. The abiotic characteristics of the habitat changed
4. Diseases that killed the older organisms disappeared

Pioneer stage (early succession)

Climax stage (late succession)

low biodiversity

high biodiversity

fluctuating abiotic factors

stable abiotic factors

Few layers

Very layered (heights of vegetation)

Closed cycles

Open cycles

Stable biomass

Increasing biomass

Pioneer stage (early succession)

Climax stage (late succession)

low biodiversity

high biodiversity

fluctuating abiotic factors

stable abiotic factors

Few layers

Very layered (heights of vegetation)

Closed cycles

Open cycles

Stable biomass

Increasing biomass

homework 

read and learn basics 1,2,3,4 and 6

do ex. 21 and 22