- Created by: charlietilford
- Created on: 04-05-15 20:20
Areas of shallow water, including lakes, ponds, marshes, rivers and flooded gravel pits. Very important to wildlife as they're relatively rare. Natural silting up and ecological succession results in the continual loss of wetlands. Many species live there all the time while other visit to drink water or to breed, e.g. frogs. Most wetlands remain ice free in the winter so they attract many birds that migrate south to escape the cold areas such as Iceland and Greenland.
Threats to wetlands:
- Drainage to produce more productive farmland
- Urban expansion on to flood plaints
- Straightening of rivers to speed up drainage/ reduce flooding risk
- Excessive recreation pressure
- Bank reinforcement to reduce flooding risk
- Pollution from industry, sewage and agriculture.
In Norfolk and Suffolk, were cut for their peat between the 12th and 14th century for use as fuel when wood supplies diminished. They flooded when sea levels rose and produced a network of about 40 broads(lakes) totallying nearly 700 hectares with 200 miles of rivers and surrounding marshland. Richest & most varied freshwater habitat in UK. Threats:
Secondary succession has replaced large areas of reed beds with carr (wet) woodland.Eutrophication due to phosphates from sewage and nitrates from fertiliser run off = decline of natural foodwebs. Introduced species (Copyu) caused problems. Recreation pressure such as litter and noise. Global climate change and sea level rise = flooding & sea water incursion.
Management: sediment removal from Broads and rivers to remove phosphates. Phosphate removal from liquid effluents at sewage works. Copyu eradication. Carr woodland and reed bed clearance followed by re-establishment of commercial reed cutting. Bank protection. Better boat design to reduce wash. Speed limits for boats. Path maintanence. Public education.
Plagioclimax habitat (maintained by external activities) usually found on sand and gravel soils. As soils are naturally infertile, heathlands haven't usually been farmed intensively. Low use of pesticides/fertilisers = many wildlife species remain. Grazing and burning prevent woodland re-establishing itself which allows smaller plants such as heather to thrive. Animal species include the sand lizard and smooth snake.
- urban expansion
- conifer plantations
- golf courses
- stopping the use of burning, a technique used in the management of heathland
The species that live in hedgerows are often those that would naturally be found in woodlands, esp. around edges/next to clearings. Types; woodland relic hedges - strips of woodland between fields as woodland was cleared, often 100s years ago. Usually rich in plant and animal life so are of great wildlife value. Planted hedges - divide up common land on open farming landscape. Some planted to provide barriers to keep livestock in .Usually have fewer plant species = lower wildlife value.
Wildlife value of hedgerows: Total area is small but of great importance. Dispersed over large area and so available ro huge number of animals. Can be used by animals that spend most of their lives in another habitat, e.g. nesting birds. Hedgerows act as biological corridors linking other habitats such as isolated woodland for species such as mice and squirrels. Reasons for loss: increase in size of arable fields for easier use of machinery, increase in farmable area and food harvests, road widening, replacement by fences which are easier to maintain, damage by vehicles which creates gaps, neglect by ceasing traditional management such as hedge-laying (cutting stems and bending ovver to produce a denser hedge base)
Threats to environment through loss of hedgerows: loss of wildlife, loss of habitats for predators that control agricultural pests, increasing wind erosion in neighbouring fields, reduction in the scenic quality of the countryside.
Originally covered with woodland but cleared to create farmland. Arable farming led to serious soil erosion so crop growing had to stop. The land was then used for sheep grazing which allowed the grass to protect the remaining thin soil but prevented the natural succession which would have re-established woodland. Important chalk grassland species = plants such as cowslips and monkey orchids, the chalkhill blue butterfly and birds including the stone curlew and skylark.
-Intensive farming with ploughing with use of fertilisers to substitute fertile soil
- improvement of the grassland using fertilisers, pesticides and re-seeding with more productive grass varieties
- urban expansion and road building
- abandonment of grazing when sheep farming is not profitable. This leads to secondary succession where thorn and scrub woodland replaces the grassland.
Traditional hay meadows weren't cut until the end of summer when the mature dry grasses could then be stored as nutritious winter fodder for livestock. By the end of the summer the annual wildflowers had flowers and produced seeds, which would have safely fallen on to the ground ensuring wildflowers for future years. No weedkillers were used and no fertilisers which could have made the grasses grow taller and shade the wildflowers. Rare species that life in meadows include the plant 'great butterfly orchid'.
Threats to hay meadows:
- Improved grassland - ground is sprayed with weedkillers then ploughed and reseeded wth fast growing varieties of grass that provide a higher crop yield. The wildflowers are killed and the reduced plant diversity means there are fewer insects and birds that feed off them.
- A change in grassland management to silage cutting - the grass is cut several times during the summer and stored wet in silage clamps. The regular cutting kills the wildflowers before they can produce seeds and destroys the nests of ground nesting birds.
When the woodlands of upland britain were cleared for fuel, the land was often used for sheep grazing, which produced a heather and grass community of great wildlife value.
Regular burning helps to maintain the moorland plagioclimax, which may be used for grouse shooting.
Threats to moorland:
- conversion to 'improved' grassland where high yielding grass varieties are plantd
-afforestation with conifers
- resevoir construction
- abandonment of grazing or grouse shooting allowing secondary succession
- increased visitor pressure as a result of the Countryside and Rights of Way Act
Important moorland species include the hen harrier, golden eagle and black grouse.
Coasts and Estuaries
Coastlines next to open oceans often have relatively stable climates because of the high heat capacity of the sea water which resists temperature changes, esp. if the coast has a consistent ocean current. Britain has a maritime climate which is warmer than many areas at the same latitude because the Gulf stream (North atlantic drift) brings warm water from the Caribbean Sea. The coastline of the UK is over 11,000 miles long and has a range of coastal habitats.
Estuaries: A rise in sea level in the medieval times flooded river valleys near the coast and produced a large number of estuaries of different types. Estuaries are very biologically productive because of the large amounts of DOM carried downstream by rivers or brought in by the incoming tides. Shallow, warm conditions also allow rapid growth of algae.
Abiotic factors in estuaries; salinity- randing from pure seawater to freshwater, depth, turbidity - clear water to water with fine suspended soldies, water flow rates - very slow to over 10mph, period of exposure to air, temp fluctuations - esp. when tides out as water has smaller seasonal temp fluctuations than air, substrate type - coarse gravel to fine clay. These characteristics produced great habitat variety & increase the no. of species that life there. British estuaries attract large numbers of migrant birds from as far as Greenland. Important species - ducks and geese.
Threats - port developments, pollution from rivers that drain into estuaries, land reclamation, pollution from industrial developments such as oil terminals.