Ecosystems

Question 1

What is a food web?

Answer 1

a complex network of interconnected food chains within an ecosystem, illustrating how energy and nutrients flow from one organism to another as they are consumed

Question 2

what do the arrows on food webs represent?

Answer 2

arrows indicate the flow of energy, point from the organism being eaten to the organism eating

Question 3

Primary producer

Answer 3

organisms that produce their own food, usually by photosynthesis

Question 4

Primary consumers

Answer 4

eat primary producers

Question 5

Secondary consumers

Answer 5

eat primary consumers

Question 6

Tertiary consumers

Answer 6

eat secondary consumers

Question 7

What is energy flow?

Answer 7

the transfer of energy from one trophic level to another

Question 8

Trophic cascades

Answer 8

Indirect effects of predator-prey relationships that impacts the whole ecosystem through food webs.
- due to the connectivity of networks

Question 9

Trophic cascade example in Yellowstone

Answer 9

Reintroduction of wolves
- predator on elk so fewer elk
- fewer elk so less herbivory on aspen trees
- more wood for beavers, so increased beavers

Question 10

Keystone species

Answer 10

a species whose removal would produce a significant effect (extinction of large change in density) in more than 1 other species

Question 11

Keystone species Kereru example

Answer 11

• disperse 3 large seed tree species which are dependent on kereru for dispersal
  Low density of kereru means less dispersal and reproduction output of these tree species, like Tawa

Question 12

Keystone species scale insects example

Answer 12

Scale insects are found under bark of trees to get to the phloem
Eats excess sugar and produces sugar filaments
Removal of mammals means geckos have room to come and eat this sugar

Question 13

What do seabirds do on land that introduces marine sources?

Answer 13

Burrow into high nutrient areas, disturbed ground and colonise inland, introducing marine nutrients

Question 14

How do seabirds add marine input?

Answer 14

Seabird guano provides nutrients to support invertebrates and reptile proportions

Question 15

Pest management affecting biotic networks

Answer 15

removal of just one species can impact the whole ecosystem, need to consider how removal of one species will impact all others

Question 16

Removing pigs and goats affect on ecosystem

Answer 16

While they destroy vegetation, removal of pigs and goats could mena increase in invasive vines

Question 17

Fluctuations in ecosystems

Answer 17

daily, seasonal, weather and temperature change

Question 18

Small scale natural disturbances

Answer 18

small patches, usually biotic, common, faster recovery time

Question 19

Large scale natural disturbances

Answer 19

large patches, uncommon and usually abiotic and catastrophic
slower recovery

Question 20

What is succession?

Answer 20

change in species composition and abundance and structure of an ecological community over time after a disturbance

Question 21

Primary succession

Answer 21

After a big disturbance, starting again from bare rock

Question 22

Process of primary succession

Answer 22

1. bare rock
2. lichen and moss, creating a soil layer, holding water
3. small annual plants
4. Perennial herbs and grasses
5. Grasses, share-intolerant plants, need light
6. Share tolerant trees

Question 23

Example of primary succession

Answer 23

Rangitoto
Reduced to bare rock after eruption, but little pockets of rock held water, supporting plant regrowth

Question 24

Secondary succession

Answer 24

Primary succession but starting from soil
disturbance like fire removing everything but soil

Question 25

Early colonising specues

Answer 25

Faciliatate the growth for later species by adding nutrients, nitrogen fixing, and soil formation

Question 26

Traits of early colonisers

Answer 26

fast dispersal, rapid growth, short stature, short lived, wide tolerance for abiotic factors

Question 27

Later arrivals or climax species

Answer 27

Slow to arrive and establish, compete for dominance on forest floor and cover

Question 28

Traits for late successional plants

Answer 28

large seeds, shade tolerant, slow growth rates, large stature, long lived, narrow niche range

Question 29

Continual disturbance

Answer 29

prevents a species from reaching climax as disturbance continues to happen, no full succession

Question 30

What does it mean for an ecological community to reach climax

Answer 30

Means it has reached the final, stable stage of succession, equilibrium, where environmental conditions are species composition stays basically the same

Question 31

Why is some disturbance important?

Answer 31

For regeneration and genetic diversity, otherwise we would only have late successional species

Question 32

Example of advantage of disturbance

Answer 32

Regular fires in Australia or the USA Some plants rely on fire to break open seeds and disperse for growth

Question 33

Ecosystem engineers

Answer 33

species that substantially modifies their environment to suit their needs, creating disturbance for others

Question 34

Example of ecosystem engineer

Answer 34

Kauri trees create layers of acidic leaf litter that affects what can grow near Kauri

Question 35

How does climate change affect disturbance?

Answer 35

effects frequency and intensity of disturbances

Question 36

How does energy enter a food chain?

Answer 36

Through a primary producer from photosynthesis, or chemoautotrophs and detritivores

Question 37

How is plant used by organisms?

Answer 37

growth and respiration, which can be passed to the next trophic level, or faeces

Question 38

Gross primary production

Answer 38

amount of energy from light/chemicals converted to chemical energy total possible amount

Question 39

Net primary production

Answer 39

gross primary production minus energy used for respiration, so the energy and biomass available for the next trophic level

Question 40

Where is the highest NPP levels?

Answer 40

tropical forests, estuaries and coral reefs

Question 41

Net ecosystem production

Answer 41

total biomass accumulation over time, all organisms contributing

Question 42

Why is there not a high NPP in the ocean?

Answer 42

Solar radiation is limited, as light doesnt filter to deep ocean Nutrient limited, which is needed for energy

Question 43

Oligotrophic

Answer 43

low nutrients

Question 44

Mesotrophic

Answer 44

medium nutrients

Question 45

Eutrophic

Answer 45

high nutrients

Question 46

Biological pump

Answer 46

movement of nutrients vertically and horizontally

Question 47

Heterotrophs

Answer 47

get energy from decomposers, not from light or chemicals

Question 48

How do decomposers affect terrestrial environment?

Answer 48

affects leaf litter, available nutrients for growing plants, faster breakdown and nutrient release

Question 49

How do decomposers affect aquatic environment?

Answer 49

breakdown is slower as algae get nutrients from water

Question 50

Range shift definition

Answer 50

a change in the distribution of species boundaries from previously known boundaries for any or all of the developmental stages, events and/or seasons

Question 51

Example of a range shift

Answer 51

Polar bears being forced to adapt to warmer climates, moving further north to follow the cold or adapting to survive as forest bears

Question 52

Biogeochemical cycling

Answer 52

movement of chemicals, nutrients and molecules from organisms to the earth to the atmosphere