L8 Flashcards
Developments of grasslands is linked to…
Forest decline after the forest maximum
What value types does grassland have?
- Agricultural
- Ecological
- Social/ amenity
Grassland History Post-Glacial period
- Tundra and grass / tall herb communities were dominant in the post-glacial period
- Grasslands supported a range of sun-loving (heliophile) species
Developments of forests confined heliophiles to…
Naturally open habitats
- above the treeline - Disturbed areas eg river margins - Steep slopes/ cliffs - Glades/ clearings - Was ideal for trees not heliophiles
Forests declined after what period?
The atlantic period
- It got cooler - Less ideal temperatures for growth - But increased recognition o the role of natural grazers
Vera cycle importance
- 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
Neolithic period
- Late forest maximum
- Early Human influence (later on)
Landnam clearances
- Small temporary clearances
- Slash and burn by neolithic farmers
Where do we have evidence of landnam clearances?
- 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
Neolithic clearances
- Proposed neolithic farmers took advantage of vera cyclesHumans may have also removed large predators excacerbating the cycles
Where do we have evidence of neolithic clearances?
- 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)
Bronze age
- Agricultural expansion and population increase
- Continuous deforestation in more populated areas and where soils allow for easy deforestation
Iron age
- Climatic change- more rainfall
- Migrant from Europe - better technology
- Permanent settlements
- Wetter soils could be cultivated
Present day grasslands
- 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
How much of grassland is of the UK?
40% of the UK
How much of the UK grassland is permanent pasture?
50%
How much of the UK grassland is rough grazing?
40% (this is lower productivity)
How much of the UK grassland is grass ley?
10% grass ley (temporary cover eg arable land)
Most grassland is…?
Agricultural crop
small amounts of ‘amenity grassland’ exist
Graminoids
- Grasses, sedges, rushes
- Herbs (forbs)
- Woody areas can still be in grasslands
Altitude
- Upland/lowland (300m contour)
pH of substrate
- Acidic/neutral (mesotrophic) / calcareous
Improved grassland (for agricultural purposes) features
- Drained
- Fertilised
- Reseeded with more desirable species (more productive)
- More nitrogen
- Sometimes not so biodiverse
Semi improved grassland vs improved grassland?
Semi- improved grassland is the same but has no reseeded plants