L3 - Conservation of natural habitats in the British Isles Flashcards
(12 cards)
Describe the habitat in the British Isles during the last interglacial period (and give the relevant dates)
The Eemian (115 - 130,000 ybp):
- Mega fauna present (e.g. elephants, rhinos, hippos)
- Like African savannah (open grassland, shrubland) maintained by large herbivores, with soggy forest
- Openness of habitat debated
Detail how the habitat of the British Isles has changed since the last ice age
- Transition from boreal to deciduous forest 10,000 bp
- Various woodland types by 4,500 bp as no large herbivores
- Loss of trees due to humans + more herbs
What record has been used to reconstruct the state of woodland from 11th century?
What did the records show?
The Domesday Book using inference
Much countryside heavily exploited for:
- Arable fields
- Meadows ( grassland for hay)
- Pasture (grassland for livestock)
- Woodlands for timber, charcoal, coppiced stems for fencing, hunting
Describe how British countryside has changed from the 1700s
1700 - 1945
- Grasslands increasingly ploughed + sowed w/ clover + grass seed
- Enclosure Acts increased control of common land by landowners
- Many chalk downs + heath converted to arable land
Since 1945
- Artificial fertilisers + chemicals
- Less sheep grazing on downs
- Very small amounts of semi-natural grassland left
- Massively more fragmentation + urbanisation
Describe the history of Nature Protection in the 20th century
National Parks and Access to Countryside Act (1949):
- Designated National Parks, AONBs, National Nature reserves (NNRs) and SSSIs
- Aimed to protect most important habitats + allow scientific research
- NNRs primarily conservation, SSSIs also contain agriculture + forestry
Give the main reasons for NNRs and SSSIs becoming unfavourable for conservation
Too much disturbance
- Burning
- Overgrazing
Too little disturbance
- Shrub encroachment
- Under-grazing
Disturbance at the wrong time
What is Calcareous Grassland?
Why is it of conservation value?
Give a brief history of its prevalence and why
Semi-natural grassland found on chalk or limestone rock
Conserved for:
a) high species richness (plants + animals)
b) cultural value
c) natural beauty
History
- First cultivated by Neolithic man - 5500 BP, easy to cultivate but not productive
- Chalk downs extensively used as pasture for large wool trade
- Warrens also formed to keep rabbits, often became main grazers until myxomatosis virus
- Has mostly now become arable or reverted to woodland/shrubs
1) Describe the unique soil conditions of chalk grasslands.
2) Describe the general make up of species and give some examples.
3) Why is grazing needed to maintain this diversity?
1) CaCO3 buffers soil from acid in rain + decomposing matter = pH 7-8
- Results in limited phosphorous but less potentially toxic Al3+ free in soil solution
2) Unique flora from soil conditions:
- 30 - 40 species in 1m^2
- plant “matrix” formed from longer lived species e.g. small tussocks, rosettes
- shorter lived interstitial plants found within matrix
- abundance of matrix plants stable, interstitial plants less so
3) Grazing prevents coarse grasses taking over the shorter-lived species
Describe two ways in which abandoned grassland can be restored to chalk grassland
Sketch a relevant graph
1) Clear scrub and sow with Bromus erectus (perennial grass) e.g. in Devil’s Dyke, Cambridge
2) Repeated mowing with removal of trimmings
- sketch graph of correlation between dominance of Brachypodium pin. and diversity
Describe where a large amount of the diversity in woodland lies and why this is declining (outside of general deforestation)
- Large diversity in the shrub and ground layer rather than the trees
- Coppiced and worked forest historically had high biodiversity from more open canopy e.g. spring ephemeral flowers thrived
- More cost effective conifer plantations now dominate, high density = ground layer species + birds lost
Where are most nature reserves found today and what are the implications?
If conservation benefit were the main consideration what are the main points for how to restore the British countryside?
Mainly found:
- Areas of outstanding beauty
- Areas of limited use
- Legacies of royalty
Implication:
- Not traditionally established to maximise conservation benefit
Main points of improvement:
- Expand + connect reserves
- Introduce large herbivores + predators
- E.g. Wicken Fen Vision aims to greatly expand area of wetland
Summarise the state of nature in Britain
- No natural habitat
- Fragments of semi-natural habitats
- Semi-natural habitats must be disturbed in specific ways to retain character
- E.g. semi-natural grassland + diverse open woodland
- Paradoxically large amounts of land management needed!
