Structure. Ecosystem management and restoration. Definitions. Ecological restoration. Ecological restoration. A few definitions Ecological restoration

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1 Ecosystem management and restoration A case study from shallow lakes Ross Thompson Structure A few definitions Ecological restoration What are we restoring? What is our endpoint? Case study shallow lakes The way forward for ecosystem management UBC Biodiversity Research Centre Definitions Ecosystem: a holistic concept that includes plants, animals, the habitats associated with with them and all the physical and chemical components of the immediate environment which together form a recognizable self-contained entity. (Begon, Harper and Townsend 1996) Definitions Ecosystem management : manipulation or intervention in an ecosystem to direct ecosystem processes and components towards a particular outcome. Ecosystem restoration : manipulation or intervention in an ecosystem to restore ecosystem processes and components to a previously existing state. Ecological restoration What are we restoring? Composition of species Who s there Population processes Who s doing it with who within species Inter-relationships of species Who s eating who between species Flows of materials and nutrients Fluxes, flows and cycling of energy and matter Ecological restoration What are we restoring for? What is our intended endpoint? A crucial point which depends on ethics and philosophy Pre human impacts? (common in countries with a recent history of human colonisation e.g. New Zealand) Pre European colonisation? (common in countries with a long history of indigenous occupation) Or should we restore in order to recreate life supporting processes or ecosystem functions? 1

2 Case Study: Management and restoration of shallow lakes Introduction to shallow lake systems Freshwater or estuarine systems which do not thermally stratify Mixed completely by wind and wave action In practice usually <10m deep Introduction to shallow lake systems Common ecosystem type Most are lowland systems Important sinks for carbon Nett absorbtion of CO 2 Highly productive systems Heavily impacted by human activities Abstraction for water Overfishing Pollution Introduction to shallow lake systems Shallow lakes usually exist in one of two alternative stable states Alternative stable state: ecosystem state which is maintained through internal ecosystem influences. Introduction to shallow lake systems Shallow lakes usually exist in one of two alternative stable states Clear water state High water clarity Aquatic weeds (macrophytes) on the bed Cloudy water state Low water clarity High phytoplankton productivity Aquatic weeds generally absent Sunlight penetrates to the lake bottom at all points CLEAR WATER STATE Nutrients trapped in sediment 2

3 Nutrient addition Sunlight penetration reduced Increased phytoplankton production Sunlight penetration further reduced FURTHER INCREASED PHYTOPLANKTON PRODUCTION Release of sediment nutrients TRANSITION TO A NEW STATE TRANSITION TO A NEW STATE Fish Aquatic invertebrates BENTHIC PRODUCTIVITY Biofilms BENTHIC PRODUCTIVITY Macrophytes WATER COLUMN PRODUCTIVITY Zooplankton and phytoplankton CLOUDY WATER STATE An alternative stable state Clear water to cloudy water change requires a perturbation Nutrient addition Sediment addition Heavy grazing of weeds by waterfowl Storm events disturbing the lake bed Cloudy water to clear water change requires a change allowing plants to reestablish A specific case study from New Zealand Waituna Lagoon 3

4 Waituna a coastal lake lagoon Waituna is the best example of a coastal lake type lagoon in New Zealand. Waituna Lagoon has a special importance to indigenous peoples (tangata whenua) Traditional source of food (mahinga kai) Identified in legislation as a site of importance to tangata whenua. Surrounding environment? The wetland complex that Waituna sits in is an internationally important wetland registered with RAMSAR Animal communities birds Sixty eight species of birds recorded Several rare migratory species an important staging point for migratory birds A number of rare and threatened species Important gamebird stocks Animal communities fish An important and valued fishery for searun and resident trout Important habitat for New Zealand native fish Plant communities marginal Special features -sub-alpine and alpine species at sea level - turf formations along the lagoon edge Plant communities aquatic Dominated by Ruppia (widgeon-grass) Can tolerate limited salt water Important food for birds Most lakes/lagoons have lost Ruppia Other plants more typical of freshwater lakes 4

5 Threats Drainage Sedimentation Reductions in water quality Drainage Lowers the water table, affecting plant communities Straightens water courses, reducing fish habitat Makes flows more flashy increasing disturbance of fish, invertebrates and vegetation Sedimentation Disturbance of the catchment causes inflows of fine sediments reduces habitat quality for fish reduces aquatic plant communities smothering reduces light nutrient storage in-filling / rushland expansion Reductions in water quality Lagoons like Waituna are naturally nutrient poor Receiving high inputs of nitrate, phosphorus and ammonia Nitrate and phosphorus are the main nutrients which limit phytoplankton growth Ammonia is directly toxic to fish There are significant threats to the Lagoon in terms of sediment and nutrient inflows. All are products of agricultural development. 5

6 Responses Important questions What is causing the reductions in water quality and how can we fix it? Waituna Creek Rapidly intensifying land use, 87% of catchment already in pasture Number of dairy units increased by 700% since 1982 Land disposal of dairy effluent and dairy factory wastes What to do? Community initiatives Waituna Landcare Group Consists of local farmers Aims to achieve environmental improvement while maintaining farm production Seek the environmental toolbox to solve their problems Initiated own monitoring program What to do? Central and local government Dept. of Conservation Supply manpower, equipment Local environmental regulatory authority Supply expertise and information Central government Funded hiring of private consultant to help the Landcare group. What s in our environmental Regulatory control Requires resources and government willingness Control dairy expansion Impose regulations on waste disposal Politically unpopular!! What s in our environmental Community consultation Requires time and patience Commitment to upskill and advise locals to aid in decision making Risk of talking the issue to death!! 6

7 What s in our environmental Active management (clear water state) Opening Lagoon to sea to drain nutrients Risk of permanent opening Developing treatment wetlands around tributaries Expensive, new technology Managing fertiliser loads to reduce nutrient loadings Requires education of farmers What s in our environmental Active management (cloudy water state) Re-establish weeds Use wind barriers to stabilise substrate Reduce bird grazing Seed weed beds Must coincide with altering the root cause of the stable state shift. What s in our environmental Active management (cloudy water state) Re-establish weeds in the lakes Food web manipulations Fish Fish manipulations have been successful in switching lakes back to a clear water state in Washington State, Holland and Denmark. It s more than just restoration The way forward for ecosystem management: Management for certain ecosystem services nutrient absorbtion, detoxification, CO 2 absorbtion Management to maximise productivity fisheries, conservation areas Management for conservation ends maximise species richness 7

8 Steps for successful management Clearly set out the intended end point Establish pre-management monitoring Actions should be guided by science but sometimes actions will be guided by incomplete science. Use management changes as experiments design, have controls Assess, recheck, monitoring into the future. We continually change the world in fundamental ways it is likely that we are going to have to manage it just as actively to protect and restore global ecosystems. 8