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Ecosystems and sustainability in a changing world > L8 > Flashcards

L8 Flashcards

1
Q

Developments of grasslands is linked to…

A

Forest decline after the forest maximum

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2
Q

What value types does grassland have?

A
  • Agricultural
  • Ecological
  • Social/ amenity
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3
Q

Grassland History Post-Glacial period

A
  • Tundra and grass / tall herb communities were dominant in the post-glacial period
    • Grasslands supported a range of sun-loving (heliophile) species
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4
Q

Developments of forests confined heliophiles to…

A

Naturally open habitats

- above the treeline
- Disturbed areas eg river margins
- Steep slopes/ cliffs
- Glades/ clearings
- Was ideal for trees not heliophiles
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5
Q

Forests declined after what period?

A

The atlantic period

- It got cooler

- Less ideal temperatures for growth

- But increased recognition o the role of natural grazers
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6
Q

Vera cycle importance

A
  • Important role in initial breaking up of the forest
    • Herbivores begin to open up an area and create a light loving environment
    • More herbivores then attracted
    • Area then expands
    • Quality of grazing declines(degraded)
    • Scrubby habitat then forms
    • Loss of grassland
    • Trees then reinvade
    • Herbivore may then open it up again many years later
    • Important in early stages of forest decline
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7
Q

Neolithic period

A
  • Late forest maximum
    • Early Human influence (later on)
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8
Q

Landnam clearances

A
  • Small temporary clearances
    • Slash and burn by neolithic farmers
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9
Q

Where do we have evidence of landnam clearances?

A
  • Decline in tree pollen
    • Increase in arable weed pollen
    • Cereal pollen records
    • Someties a charcoal layer
    • First types of human influence in driving forest decline
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10
Q

Neolithic clearances

A
  • Proposed neolithic farmers took advantage of vera cyclesHumans may have also removed large predators excacerbating the cycles
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11
Q

Where do we have evidence of neolithic clearances?

A
  • Longer periods each time
    • Cycles of clearance
    • More extensive and permanent deforestation in some parts of Britain
    • Associated with well populated areas
    • Greater agriculture demand and industry (mines etc)
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12
Q

Bronze age

A
  • Agricultural expansion and population increase
    • Continuous deforestation in more populated areas and where soils allow for easy deforestation
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13
Q

Iron age

A
  • Climatic change- more rainfall
    • Migrant from Europe - better technology
    • Permanent settlements
    • Wetter soils could be cultivated
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14
Q

Present day grasslands

A
  • Makes up approximately 40% of the UK
    • 50% permanent pasture
    • 40% rough grazing (lower productivity)
    • 10% grass ley (temporary cover eg arable land)
    • Small amounts of ‘amenity grassland’
    • Most grassland is agricultural - most grass is a crop
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15
Q

How much of grassland is of the UK?

A

40% of the UK

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16
Q

How much of the UK grassland is permanent pasture?

A

50%

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17
Q

How much of the UK grassland is rough grazing?

A

40% (this is lower productivity)

18
Q

How much of the UK grassland is grass ley?

A

10% grass ley (temporary cover eg arable land)

19
Q

Most grassland is…?

A

Agricultural crop

small amounts of ‘amenity grassland’ exist

20
Q

Graminoids

A
  • Grasses, sedges, rushes
  • Herbs (forbs)
  • Woody areas can still be in grasslands
21
Q

Altitude

A
  • Upland/lowland (300m contour)
22
Q

pH of substrate

A
  • Acidic/neutral (mesotrophic) / calcareous
23
Q

Improved grassland (for agricultural purposes) features

A
  • Drained
    • Fertilised
    • Reseeded with more desirable species (more productive)
    • More nitrogen
    • Sometimes not so biodiverse
24
Q

Semi improved grassland vs improved grassland?

A

Semi- improved grassland is the same but has no reseeded plants

25
Q

Semi-natural / unimproved grassland state of management?

A
  • Only managed to maintain it as a grassland (grazing/cutting)
    • Stay as grassland
    • If no grazing/cutting they would go back to woodland
    • 100,000 ha out of 4.5 million in the UK
    • Can be very biodiverse
26
Q

Are semi-natural / unimproved adapted to stays as grasslands?

A

yes

- Adapted to stay as grasslands

- Evolved as grazed/ burnt systems

- Historically adapted to stay as grasslands, now humans interfere and keep as grassland

- Copes with biomass removal

- Grazing and nutrient takes away nutrients

- Often not used for hay cutting as this requires fertiliser addition
27
Q

Adaptations of grassland plants

A
  • Grazing/mowing results in the repeated partial defoliation of plants or avoid defoliation

Intercalary meristem

Rhizomes (soil)

Adpressed growth

Low palatability

Ephemeral

28
Q

Intercalary meristem

A
  • Base meristem
    • Only in graminoids and horsetails
    • Grazed plants can easily regrow from basal meristem
    • Removal of new growth doesn’t matter
    • Apical meristems leaves behind new growth, so meristem is removed when cut
29
Q

Rhizomes (soil)

A
  • Rootstalks provide new nodes for growth
    • Grazed plants can spread without flowers
    • Herbs, Grasses, woody plants
30
Q

Adpressed growth

A
  • Negatively phototropic rosettes
    • Plant is flat to the ground

Not easily grazed

31
Q

Low palatability

A
  • Spines
    • Woody tissues
    • Distastefulness and toxins
32
Q

Ephemeral

A
  • Grow when the opportunity arises
    • Exploit bare patches of soil
    • Grow/reproduce during periods of limited grazing
    • Avoiding grazing period
33
Q

Importance of pH

A
  • Has an effect upon grassland plant species composition
    • Some species grow over a very wide pH range
    • Calcifuge species grow in acidic soils
    • Calcicole species grow in calcareous soils (alkaline)
34
Q

Importance of pH on nutrients

A
  • Effect of pH on plants largely mediated by its influence on availability of other ions
    • Some of these ions can be toxic, whilst some are crucial to plant growth
    • Toxic compounds are more bioavailable in acidic soils
35
Q

Distribution of the calcicole and limestone grasslands

A
  • Cant grow in an acidic soil
36
Q

Grimes Humpback curve

A
  • Curve of productivity and species richness
    • Harsh environments and low productivity results in few species
    • Productive ecosystems have dominance of a few species
    • Few species will go rapidly leading to competitive exclusion
37
Q

Maximum potential biodiversity

A
  • Intermediate productivity
    • No harsh environment
    • Not enough productivity for competitive exclusion

Shown in many areas of the world

38
Q

what is the reservoir effect?

A

small pool of species that can cope with acidic soil

39
Q

high nutrients favours…

A

dominance and hence low diversity

40
Q

soil pH leads to less…

A

actual biodiversity as few species are adapted

Ecosystems and sustainability in a changing world (21 decks)

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