Date post: | 08-Apr-2018 |
Category: |
Documents |
Upload: | samuelsundaramas |
View: | 226 times |
Download: | 0 times |
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 1/28
Loss of habitats: wetlands
Case study: The Norfolk Broads
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 2/28
What is a wetland?
� A very productive ecosystem- second to
the TRF
� An ecosystem that functions viainputs,outputs,energy and nutrient flows
and feedback loops.
� Temperate wetlands- lowland wet grass
and upland and lowland peat bogs
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 3/28
Traditional Broadland scene at
Howe Hill� Reed swamp
� Drained by rivers and
dykes, drainage
channels
� Grazing
� Traditional windmill
� Carr woodland
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 5/28
Traditional management
supports a diverse ecosystem� Summer grazing or hay cut for winter fodder
� Winter seasonal flooding too boggy to graze
� Traditional habitats fostered for lapwings,curlews,snipeand some rarer breeds.
� Provides winter feeding ground for migrant wildfowl-e.g.widgeon,teal,shoveler, pintail,Bewick and whooper swans.
� Ditches and dykes form barriers to the movement of grazing cattle and provide drinking water.
� Grazing cattle disturb insects especially at drinking sitesso the insects are easy food for birds ie sustain the foodchains.
� Waders, summer visitors and breeding birds need insectrich environments to feed their young.
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 7/28
The impact from intensive
farming� Drained land for more intensive agriculture (arable)reduces species diversity as habitats are lost
� Hay cutting replaced by silage production and moreintensive grazing
� Alters the functioning of the system as the variety of niches disappear
� Ditches and dykes lost
� Range of plants decreases
� Number and variety of insects declines
� Loss of food for carnivores ( birds and mammals)
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 8/28
Application of fertilisers
� The rapid rise in the use of fertilisers
� Intensification so that more fertilisers needed to maintainyields
� Nitrates very soluble so large amounts dissolve in soilwater
� More efficient drainage so water infiltrating into the soilenters the ditches, rivers and broads more rapidly.
� Water in ditches and broads becomes sediment and
nutrient rich� Eutrophication leads to murky water, thick mud and
reduced biodiversity
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 9/28
The impact from a changing
economy� Diversification into tourism
� Increasing pollution from sewage and
slurry� Rapid rise in greenhouse gases and
resulting global warming. Key concerns
are rising sea levels, the threat of flooding
and the incursion of salt water, and
warmer summers which may dry out some
wetlands.
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 10/28
Barton Broad Clearwater
Project 2000� A significant area, the second largestBroad
� A National Nature Reserve, owned byNorfolkWildlife Trust
� Part of the Ant Broads and Marshes SSSI
� A Ramsar Site ( An international
designation from the Ramsar ConventiononWetlands)
� An EU Special Protection area for birds.
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 11/28
Reeds on the edge of Barton Broad
� The reedswamp is a natural
cushion (rond) between water
and grazing
� Protects the banks from
erosion� Important habitat for wildlife,
spawning ground for fish and
site for dragonflies.
� Has aesthetic value
� Was part of the rural economy� Is susceptible to high
concentrations of nitrates.
� Is an indicator of clear water
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 13/28
The management of Reeds
� Restoring the aquatic environment will support
reed growth and provide ecological niches for
fish and dragonflies
� Scrub clearance is necessary in some places
� A market is being found for reeds for thatching.
The British Reed Growers Association is
supported by the Broads Authority for goodcommercial and conservation practice
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 14/28
Harvesting the marsh grazing
� The Wetlands harvest project has attracted finance from
a range of sources for a harvesting machine to cut the
marsh grazing to cope with the boggy environment and
pioneer a drying technique to pellet the marsh hay for
fuel or fodder so that drainage is not necessary for
farmers to make some profit
� Grazing trials are being monitored to establish the level
of grazing that is sustainable
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 15/28
Carr woodlandCarr woodland alder, sallow and birch trees, guelder rose, buckthorn dog rose and
brambles in the shrub layer.
Ferns, mosses, liverworts and lichens are found in the damp shady undergrowth
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 18/28
Carr management
� Some has been cleared to create more open fen ± reeds
� Mature carr needs little management and is part of thecharacteristic landscape
� Younger carr is being managed by English Nature andlocal landowners to maintain species diversity
� There is economic potential from coppicing alder for wooden piling to replace steel piling along the Bure.
� Coppicing can improve bank access and is favoured by
sailors so is appropriate for some areas
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 19/28
The Barton scheme
Clearwater 2000� An integrated project that recognises the
role of agriculture and tourism in the local
economy but is recreating a rich wetland
environment which attracts a wide range
of plants, insects, birds and mammals.
� A sustainable approach
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 21/28
Measures taken before 2000 that
compliment the project
� Controlling nitrogen fertilisers. This area is
in a NSZ nitrogen sensitive zone where
the application of fertilisers is strictly
controlled.
� Agro environmental policy
� New sewage treatment plants installed
� Dredging to remove phosphate rich sludge
from the broads
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 22/28
Agro environmental policy- hedge
planting to protect soils from
erosion and encourage wildlife
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 23/28
Autumn and spring ploughing
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 24/28
Mud pumping and silt lagoons
Clearly, one way to make a big impact (even if not a permanent one) on the phosphorus levelsin the water of the broad was to get rid of the
thick bed of nutrient-rich mud, lying on thebottom. In Nov 1995 the huge suction dredgingoperation began and contractors removed300,000 cubic metres of phosphate-rich mud(the equivalent of 160 Olympic-sized swimmingpools) A network of settlement lagoons werecreated on 22 hectares of nearby fields to holdthe silt that was removed.
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 25/28
Mud pumping, phosphorous
removal at sewage plant and silt
lagoons
8/7/2019 Barton Broad
http://slidepdf.com/reader/full/barton-broad 26/28
Biomanipulation to clear the water
and restore an ecological balance
� Understanding thefood chains meansthat daphnia have
been encouraged tofeed on the excessivealgae
� Fish are trapped andrestricted so that theydo not eat too manydaphnia until thewater is cleared