Download curriculum in natural environmental science, vol. 2, 2010

Conservation, restoration
and effects of climate
change on wetlands
Dr Debbie Chapman
School of Biological, Earth and Environmental Sciences
University College Cork, Ireland
NEAR
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curriculum in natural environmental science, vol. 2, 2010
Value of wetlands
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Essential habitat for rare or endangered species
Commercial fisheries
Recreational fisheries
Natural improvements to water
quality
Overwintering habitat for waterfowl
Reducing erosion and buffering storm impacts
(coastal wetlands)
Mitigating impacts of sea level rise (coastal
wetlands)
Wetland loss: examples
UK East Anglian Fennland
 17th Century: 3,380 km2
 Present time: about 10 km2
USA
 16th Century: 900,000 km2
 Present time: 400,000 km2
(California and Ohio lost 91% and
90% respectively)
Reasons for loss
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Natural succession (usually matched by creation
of new wetlands)
 Drainage and reclamation to create agricultural
land
 Lowering of water
table through groundwater abstraction
 Interference with
hydrological regimes
(e.g. impoundment of
rivers, coastal
development)
Tree stumps in the reservoir
created by impoundment of a
river for a hydrolectiricty
scheme in Southern Ireland
Degradation of coastal marshes
Sea level rise and land subsidence need to be
matched by sediment and organic matter
accumulation
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Human activities are leading to
an imbalance by decreasing
sediment accretion
 Creation of barriers to
landward marsh growth,
e.g. roads, sea walls
 Harvesting of trees
 Disturbance of hydrological
regimes
A causeway has
separated this wetland
from the coast and
created an artificial
lagoon of less value to
waterfowl
Climate change projections
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Global mean temperature change from 1990:
1.4–5.8 °C
 Sea level rise: 10–90 cm by year 2100
 Change in frequency and intensity of extreme
climate events, e.g. increase in number of hot
days, fewer cold days, more frequent intense
downpours, increased frequency and intensity of
floods and droughts
 The greatest changes in temperature and
precipitation likely to occur in the northern
hemisphere
Possible impacts from projected
extreme climate events
Climate event
Projected impact
Higher max temps, heat
waves
Heat stress in wildlife
Higher min temps, fewer cold
days
Extended range of pests and disease
vectors
More intense precipitation
events
Increased flooding, increased soil
erosion, landslide damage
Summer droughts
Reduced water quantity and quality,
risk of fires
Intensified tropical cyclones
(wind and rain)
Coastal erosion, damage to coastal
infrastructure, physical damage to
coastal ecosystems such as
mangrove swamps
Climate impacts on wetlands
 It
is likely that climate change impacts on
water resources over the next 20 years will
be small relative to the impacts of other
changes
 Most
likely impact on wetlands will be
through alteration of hydrological regimes
and occurrence of extreme weather events
Climate change: Inland wetlands
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Change of plant communities
Invasion or expansion of alien species
Tropical wetland floodplains
replaced with salt water
habitats and salt
tolerant species
Loss of feeding/breeding
grounds for birds and fish
Interrupted migration
Regular tidal inundation
routes for birds
leaves insufficient feeding
area exposed for the birds
Climate change: Coastal wetlands
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When combined with other human-induced losses,
coastal wetland loss could be as high as 70%
Vulnerable wetlands are low-lying deltas and coastal
plains – estuaries, lagoons, salt-marshes, mangroves
Climate change will lead to:
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Landward intrusion of seawater
Coastal inundation and storm
surge flooding
Inland and upstream salinity
intrusion
Changes in ecosystem structure
caused by changes in temperature
and rainfall patterns
Attempts to restrict coastal erosion
have been abandoned at this beach
in Western Ireland
Projected impacts of climate change in
Europe: inland wetlands
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Increased winter rainfall and river flows, leading to
flooding
Decreased summer flows and higher temperatures
leading to low dissolved O2 and poor water quality
Increased fish productivity
and a shift towards cyprinid
and percid fish
Peatlands will expand northwards, possibly replacing
tundra
Loss of isolated depressional
wetlands may affect migratory
Evidence of a breeding
population of carp in a
and breeding bird populations
shallow lake in Ireland
Projected impacts of climate change in
Europe: coastal wetlands
Mediterranean and Baltic deltas, estuaries and salt
marshes particularly at risk from sea level rise
(extent of development on coasts restricts
options for conservation/restoration)
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Possible loss of salt marshes and
intertidal estuarine zones will
reduce habitats for wildlife,
fish and migratory birds
Distributions of some shorebirds
already occurring due to
changes in regional temperature
patterns
Rhône, Po and Elbe deltas
susceptible due to existing reduced
sediment loads
Erosion of rare estuarine peat
saltmarsh in the West of Ireland
Conservation and restoration
 Conservation
- long-term preservation and
protection of the functions and values of
wetlands
– returning a degraded
wetland (rehabilitation) or former wetland
(re-establishment) to a pre-existing
condition or as close to that condition as
possible
 Restoration
Conservation of coastal wetlands for
impacts of climate change
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Manage landward reinstatement of coastal
wetland habitats through removal of sea defense
structures
 Design multiple-use reserves and protected
areas which incorporate corridors that would
allow for migration of organisms as a response
to climate change
 Expand aquaculture that could relieve stress on
natural fisheries
 Integrated resource management
Restoration: Passive
 Removal
of cause of degradation and
allow natural regeneration (e.g. removal of
grazing livestock)
 Not always practicable (close access to
water and wetland species essential)
 Low cost
 Likely that the resultant wetland will
resemble the surrounding environment
Restoration: Active
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Appropriate when wetland
is severely degraded
 Examples: weirs and
culverts, intensive
planting, invasive species
control, substrate creation
 Considerable design work
needed
 Construction costs may
be high
The London Wetland Centre:
Wetland restoration in the
suburbs on London to create a
bird reserve
http://www.wwt.org.uk/visit-us/london
Restoration: traditional versus soft
engineering solutions
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Traditional “hard”
engineering solutions
replace natural
ecosystem functions
with human-designed
structures, e.g. concrete
embankments to
prevent erosion
“Soft” solutions include
planting native species
such as willows, log
banks and geotextile
materials
Concrete embankments
Restoration of banks along River
Thames with native vegetation
Restoration: important factors to
consider
 Hydrology
 Topography
 Soil
and geology
type
 Vegetation and animal life
 Land ownership
 Stakeholder involvement
Examples of wetland problems and possible
remediation methods
Problem
Cause
Restoration action
Poor water quality
Nutrient/sediment run-off,
sediment erosion
Change land-use practices,
install vegetation
buffers/sediment traps
Altered hydrology due to
drainage
Presence of ditches and
drains, embankment
cutting off wetland from
water source
Fill ditches, remove
embankment, install gates/weirs
Raised elevation
Dumping or in-fill
Remove surplus material
Subsidence
Removal of soil, depletion
of groundwater
Allow natural sedimentation,
add sediment
Loss of biodiversity
Change in habitat
Planting of native species, allow
species to recolonise,
Loss of native plants
Change in hydrology,
change in land use,
invasive species
Restore hydrological regime,
remove invasive species and
alter conditions that favour them
Restoration: usefulness and feasibility
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Will there be environmental benefits (e.g. improved
water quantity, reduced eutrophication, biodiversity
conservation, flood control)?
 What is the cost effectiveness of the proposed
rehabilitation?
 What options, advantages or disadvantages will the
restored area provide for local people and the region?
 What is the present and possible future ecological status
of the project?
 What is the status of the area in terms of present land
use?
 What are the main socio-economic constraints?
 What are the main technical constraints?
http://www.ramsar.org/key_guide_restoration_e.htm
Sources of information
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Ramsar Convention Secretariat, 2007 Inventory, assessment, and
monitoring: An Integrated Framework for wetland inventory,
assessment, and monitoring. Ramsar handbooks for the wise use of
wetlands, 3rd edition, vol. 11. Ramsar Convention Secretariat,
Gland, Switzerland.
Ramsar Convention 2002 Climate change and wetlands: impacts,
adaptation and mitigation. Ramsar COP8 Doc 11: Climate Change
and Wetlands.
Interagency Workgroup on Wetland Restoration (IWWR) 2003 An
Introduction and User’s Guide to Wetland Restoration, Creation and
Enhancement. US Environmental Protection Agency, Office of
Water, 95 pp.
http://www.epa.gov/owow/wetlands/pdf/restdocfinal.pdf
USEPA, 2000 Principles for the Ecological Restoration of Aquatic
Resources. EPA841-F-00-003. Office of Water (4501F), United
States Environmental Protection Agency, Washington, DC. 4 pp.