4/6 - ICH - Succession & samping

Question 1

Define Species richness

Answer 1

Species richness = number of species in an ecosystem

Question 2

What results in a stable ecosystem?

• What is the diversity like
• What are the food webs

Answer 2

In less extreme environemnts:

• Diversity of organisms is usually high
• Biotic factors dominate and abiotic factors are not extreme
• Food webs are complex - many inter-connected food chains
• Results in a STABLE ECOSYSTEM - if population of one species declines, there’s alternative food sources

Question 3

What results in a unstable ecosystem?

• What is the diversity like
• What are the food webs

Answer 3

In extreme environments:

• Diversity of organisms is generally low
• Abiotic factors are extreme & few species have adaptations allowing them to survive ∴ abiotic factors dominate
• Food webs are relatively simple - few food chainss or connections as few producers can survive
• Results in UNSTABLE ECOSYSTEM - change in population of 1 species can cause really big problems for other species

Question 4

What is succession?

Answer 4

Succession = Th way different species which amke up a community change over time

Question 5

Define primary succession

Answer 5

Primary succession = New area of land has been newly fomed for exposed to bare rock. No soil/ organic material to begin with

Question 6

Define secondary succession

Answer 6

Secondary succession = Land where soil is present but there’s NO animal or plant species

Question 7

Define deflected succession

Answer 7

Deflected succession = Human activity that halts the natural succession process

Question 8

Define pioneer species and climax community

Answer 8

Pioneer species = First organisms to colonise a area

Climax community = Final stage of succession where the community is in a stable stage

Question 9

How is the diversity of a community expressed?

Answer 9

Simpsons index of biodiversity

N = Total no’ of organisms of all species in the habitat

n = Total no’ of organisms of each species

Question 10

What is ecological succesion? What is a sere?

Answer 10

Ecological succesion = The changes to an ecosystem over time

Sere = Each stage of succession

Question 11

What does each sere of succession result in?

Answer 11

A less hostile environment to increase the diversity

Question 12

5 adaptations of pioneer species

Answer 12

• Produce large quantities of seeds/ spores which travel by wint to be deposited on new land
• Seeds that germinate rapidly
• Photosynthesise to produce their own energy
• Tolerence to extreme envionments
• Can fix N₂ from the atmosphere so increase mineral content of soil

Question 13

Define plagioclimax

Answer 13

Plagioclimax = Stages in succession where artificial or natural factors prevent the natural climax community from forming

Question 14

What is a keystone species?

Answer 14

Keystone species = Species which a ecosystem depends upon. Loss of this species can lead to very large affects on the ecosystem

Question 15

Why must succession happen?

Answer 15

Environment is constantly changing, without adaptations the organisms would become extinct

Question 16

Why do pioneer species disappear quickly after succession beging to occur?

Answer 16

They highly specialised and are unable to compete well for resources

Question 17

2 ways to ensure that samples reflect the true population when investigating the numbers and distribution of a habitat

Answer 17

• Take a relatively large sample
• Ensure there;s no personal bias. Must be an random to avoid observer bias

Question 18

Explain what is happening in the graph to abiotic conditions, plants and the animals in the sand dune

Answer 18

Question 19

What can be used to represent the abundance of a plant when sampling a habitat?

Answer 19

The % cover

Question 20

Name 2 forms of random sampling

Answer 20

Quadrats and transects

Question 21

• What type of quadrats can you get?
• What is each type used for?
• How are they used?

Answer 21

Frame quadrat:

• Placed on the ground at random points. Count the number of the squared that have the plant to find population density, freq or % cover
• Used to study distribution of plants in a fairly uniform area

Point quadrat:

• Quadrat with a reduced size to a single point
• Used to study the distribution of plants. Point quadrats are often used with transects
• Point frame is usually used of approx 10 pins 5cm apart. By lowering the pins in turn and recording the no’ of hits on a particular species of plant, freq or % cover can be estimated

Question 22

What are the different types of transects that can be used in sampling?

Answer 22

Line transects:

• Tape measure is placed along the transect and the species that touch the tae measure are recorded

Belt transects:

• Data is collected along the transect using frame quadrats placed next to each other

Iterrupted transects:

• Instead of investigating the whole transect of either a line or a belt, you can take measurements at intervals e.g. by placing point quadrats at right angles to the direction of the transect at set intervals along its length e.g. every 2m

Question 23

How do you ensure there is no observer bias during sampling?

Answer 23

In short:

• Make a grid
• Give the grid coordinates
• Use some form to randomly generate the numbers for the coordinates

Question 24

What are the 3 measures to describe the distribution fo plants?

Answer 24

Population density = No’ of individual plants of a particular species in a given area

Frequency = Based on no’ of quadrats (ordinary or point) in which the species occur in e.g. 3 out of 10 pins hits a dandelion plants, freq = 30%

% cover = Measures proportions of the ground in a quadrat occupied by a species

Question 25

Give 3 methods to sample animals that are moving

Answer 25

Aquatic animals = net Flying insects = Sweepnet Ground insects = Pitfall trap

Question 26

Decribe another method used in sampling by which allows the estimate population size to be made of active animals

Answer 26

_Mark, release, recapture:_ 1. Use a trapping method to capture a no' of animals fom the population begin investigated 2. Mark these animals in a way that causes no hard + is inconspicious 3. Release them + allow sufficient time for them to disperse back into the population which they have been taken from 4. Useing precisely the same trapping method at the start, capture a second sample. Count the no' of the animals that are marked and the no' that are not marked **Estimated pop = (no' of animals released x total no' of animals in 2nd sample) / no' of marked in second sample**

Question 27

Formula for **estimated population size = ?**

Answer 27

Question 28

What are the 3 types of non-random sampling?

Answer 28

**Opportunistic** * Weakest form of sampling as it may not be represntative of the popultion * Uses organisms that are conveniently available **Stratified** * Some populations can be divided into a number of **strata** (sub-groups) based on a partcular characteristic * A random sample is then taken from each of these strata proportional to its size **Syetematic** * Sampling different areas within an overall habitat * Using a line or belt transect

Question 29

Formula for **species index of biodiversity** What does the answer indicate?

Answer 29

**N** = total no' of organisms of all species in the habitat **n** = total no' of organisms of each species The closer to 1 the answer is, the more diverse the habitat

Question 30

Define **genetic diversity**

Answer 30

**Genetic diversity** = Variation of alleles within a species

Question 31

Define **species diversity**

Answer 31

**species diversity** = The number of different species (species richness) and the abundance of each species (species eveness) in an area

Question 32

Define **Habitat diversity**

Answer 32

**Habitat diversity** = The number of different habitats in an area