st: with reference to figure 1 outline how...
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QU: How can drought conditions impact on the functioning of ecosystems? AIM: To example wetlands as a drought prone ecosystem.
Groundwater aquifer
ST: With reference to figure 1 outline how groundwater aquifers can impact upon blue and green water flows and stores. (6)
Ext: Name and describe how two ecosystems may be affected in figure 1.
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Today
Time to save work Use Lesson 21 'Amazon drought event' for this.
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World wetland distribution
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BB
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C
TASK:
a What climatic conditions encourage wetlands in the labelled locations?A High amounts of convectional rainfallB Low evaptrans rates, short summer season.C Exposure to regular Atlantic storms and rainfall
EXT: What physical geographical factors encourage wetland formation?
Flat, poorly drained land. Deep soils and impermeable bedrock
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https://www.youtube.com/watch?v=G0Mes5YyFY0Watch by way of introduction
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Globally a significant carbon trap.
Releases water slowly to maintain river and ground water flows.
Provides vital food chain support to migratory birds
TASK: Stick in your copy of the above diagram and then refer to the information sheet.
1 Sort each statement on the diagram into two columns, headed ECOSYSTEM SERVICES and ECOLOGICAL FUNCTIONING.Use the sheet to find out what these terms mean if you are not sure.
2. List 5 specific ways in which drought may affect a wetland ecosystem.
EXT: Wetland habitat is being recreated at Bathampton meadows, upstream of Bath city centre. Explain what you think the main justification for this is.
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What do you remember? You were asked for 'SPECIFIC WAYS' that drought affects wetland ecosystems. Without looking on the sheet or at your notes, comment on each photo or diagram.
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In the short term, drought conditions could benefit Herons at the detriment of Snappers? How?
An autumn drought could be less severe than springtime and allow the ecosystem to be more resilient. How?
Why might a hit on Algae and Bacteria from drought conditions really test the resilience of the ecosystem?
Wetland drought resilience
The RESILIENCE of wetland ecosystems depends on timingand duration of the drought.TASK: From class discussion bullet point ideas/answersto each question on your copy of the diagram below.
Ext: What is more significant before critical thresholds are crossed, duration or timing? Justify your answer.
answers next slideTeacher note
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Concentrates prey in pools and reduces habitat of prey.Predators benefit initially.
Breeding season over and newgeneration created. If the drought duration is short there are plenty ofnumbers to regenerate and breed the following year.
These are the primary producers of the whole food chain. Without whichall predatory species above them suffer losses.
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quick reminderhttps://www.youtube.com/watch?v=G0Mes5YyFY0
Amazonia drought (forests), Wetlands. Sahel.
Using named examples, suggest two impacts of drought on ecosystem functioning. (6 marks)
Plenary How to apply this to exam Q's.
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Resource slides and extra reading
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Wetlands are ecosystems characterised by periods of saturation or inundation. Because they are not all constantly wet, the species occurring in wetlands are adapted to periods of dryness. However, drought events are periods of extreme aridity during which species may disappear and physical characteristics, such as soils, may change. Recovery of wetlands depends on the intensity and duration of the drought and the proximity of species reservoirs to support recolonization. If intensity, duration or frequency of droughts increases in the future, greater changes may result and the ability of wetlands to recover may be compromised.
Our results highlighted that:
Riverfed wetland ecosystems are more resilient to drought than rainfed wetlandsWetlands in the south and east of England and Wales are more likely to be altered by climate change than those in the north and west
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Wetlands Store Floodwaters and Carbon
According to the U.S. Environmental Protection Agency (EPA), bottomland hardwoodriparian wetlands along the Mississippi River used to store 60 days of floodwaters but now, because of draining and filling, they only have the capacity to store 12 days of floodwaters.
As living systems that support dense plant life, wetlands not only capture polluted stormwater, they also capture and store carbon (a potent greenhouse gas that contributes to climate change), potentially slowing the rate of global warming.
Wetlands Sustain Vulnerable Fish and Wildlife
Furthermore, the habitat benefits of wetland restoration are potentially enormous. Species that depend on shallow water habitats that are subject to drying, like wetlands, are the most highly vulnerable to climate change in droughtprone regions of the U.S. In Iowa, constructed wetlands have been providing breeding habitat for trumpeter swans.
Wetlands can therefore do triple duty to reduce climate change impacts—storing floodwaters, capturing carbon, and sustaining biodiversity. Restoration of natural infrastructure like freshwater wetlands should become a key piece of our national climate change adaptation strategy.Their recent report suggests that conservation of wetlands and more “green infrastructure” to capture surface runoff can reduce the intensity of flood events and improve water quality. This makes a strong case for reestablishing networks of wetlands across the interior U.S.
Freshwater wetlands upstream can improve water quality by capturing and filtering fertilizer pollution before it makes its way into rivers and eventually the Gulf of Mexico, where it contributes to growing oxygendepleted “dead zones” otherwise known as “hypoxia.”Wetlands Increase Climate Change Resilience
The greatest opportunities for increasing resilience to climate extremes in the U.S. Corn Belt region right now are in the agricultural part of the landscape. By reducing tillage of the soil, maintaining and restoring wetlands, we can store more water in the soil, in the water table and on the landscape, meaning less polluted water rushing downstream to create floods and dead zones, and more stored groundwater to protect terrestrial plants against drought.
One definition of agricultural sustainability in a changing climate could be helping to meet the food needs of a growing population in ways that benefit, rather than harm, the environment. Part of the solution to climate impacts in the interior U.S. will be improving how we manage water on the landscape. This means demonstrating the value of wetlandrelated practices to improve water quality and reduce floods, while simultaneously increasing the resilience of farm operations to extreme weather events.
Stacy SmallLorenz is a Senior Scientist in the Ecosystems program of Environmental Defense Fund. She holds a doctorate in Avian Ecology from the University of MissouriColumbia and has devoted her 20 year career to all aspects of habitat conservation, with a particular emphasis on wetland and river ecosystem restoration.
Author
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Attachments
https://www.youtube.com/watch?v=G0Mes5YyFY0
https://www.youtube.com/watch?v=ft_2nj96jLM