Nibedita Mukherjee
University of Cambridge, Zoology, Department Member
- William J Sutherlandedit
1) Many areas of science, including conservation and environmental management, regularly require engaging stakeholders or experts to produce consensus or technical inputs. The Delphi technique is an iterative and anonymous participatory... more
1) Many areas of science, including conservation and environmental management, regularly require engaging stakeholders or experts to produce consensus or technical inputs. The Delphi technique is an iterative and anonymous participatory method used for gathering and evaluating such expert-based knowledge.
2) We outline the methodology of the Delphi technique and provide a taxonomy of its main variants. In addition, we refine the technique by providing suggestions to address common limitations (e.g. time consumption, attrition rate) in order to make the method more suitable for application in ecology and conservation.
3) A comprehensive search for studies that have applied the Delphi technique in conservation and environmental management resulted in 36 papers. The Delphi technique has been applied to a range of issues, including developing decision support systems and predicting ecological impacts of climate change.
4) The papers reviewed suggest that the Delphi technique is an efficient, inclusive, systematic and structured approach that can be used to address complex issues. A major strength compared to other group-based techniques is the reduced influence of social pressures among respondents.
5) The Delphi technique is relatively little used and seems undervalued. Given its wide range of possible applications it could be applied more widely in evaluating evidence and
providing expert judgments.
2) We outline the methodology of the Delphi technique and provide a taxonomy of its main variants. In addition, we refine the technique by providing suggestions to address common limitations (e.g. time consumption, attrition rate) in order to make the method more suitable for application in ecology and conservation.
3) A comprehensive search for studies that have applied the Delphi technique in conservation and environmental management resulted in 36 papers. The Delphi technique has been applied to a range of issues, including developing decision support systems and predicting ecological impacts of climate change.
4) The papers reviewed suggest that the Delphi technique is an efficient, inclusive, systematic and structured approach that can be used to address complex issues. A major strength compared to other group-based techniques is the reduced influence of social pressures among respondents.
5) The Delphi technique is relatively little used and seems undervalued. Given its wide range of possible applications it could be applied more widely in evaluating evidence and
providing expert judgments.
Research Interests:
Mangroves are threatened worldwide, and their loss or degradation could impact functioning of the ecosystem. Our aim was to investigate three aspects of mangroves at a global scale: (1) their constituents (2) their indispensable... more
Mangroves are threatened worldwide, and their loss or degradation could
impact functioning of the ecosystem. Our aim was to investigate three aspects
of mangroves at a global scale: (1) their constituents (2) their indispensable
ecological functions, and (3) the maintenance of their constituents and functions
in degraded mangroves. We focused on answering two questions: “What
is a mangrove ecosystem” and “How vulnerable are mangrove ecosystems to
different impacts”? We invited 106 mangrove experts globally to participate in
a survey based on the Delphi technique and provide inputs on the three
aspects. The outputs from the Delphi technique for the third aspect, i.e. maintenance
of constituents and functions were incorporated in a modeling
approach to simulate the time frame for recovery. Presented here for the first
time are the consensus definition of the mangrove ecosystem and the list of
mangrove plant species. In this study, experts considered even monospecific
(tree) stands to be a mangrove ecosystem as long as there was adequate tidal
exchange, propagule dispersal, and faunal interactions. We provide a ranking of
the important ecological functions, faunal groups, and impacts on mangroves.
Degradation due to development was identified as having the largest impact on
mangroves globally in terms of spatial scale, intensity, and time needed for restoration.
The results indicate that mangroves are ecologically unique even
though they may be species poor (from the vegetation perspective). The consensus
list of mangrove species and the ranking of the mangrove ecological
functions could be a useful tool for restoration and management of mangroves.
While there is ample literature on the destruction of mangroves due to aquaculture
in the past decade, this study clearly shows that more attention must go to avoiding and mitigating mangrove loss due to coastal development (such as
building of roads, ports, or harbors).
impact functioning of the ecosystem. Our aim was to investigate three aspects
of mangroves at a global scale: (1) their constituents (2) their indispensable
ecological functions, and (3) the maintenance of their constituents and functions
in degraded mangroves. We focused on answering two questions: “What
is a mangrove ecosystem” and “How vulnerable are mangrove ecosystems to
different impacts”? We invited 106 mangrove experts globally to participate in
a survey based on the Delphi technique and provide inputs on the three
aspects. The outputs from the Delphi technique for the third aspect, i.e. maintenance
of constituents and functions were incorporated in a modeling
approach to simulate the time frame for recovery. Presented here for the first
time are the consensus definition of the mangrove ecosystem and the list of
mangrove plant species. In this study, experts considered even monospecific
(tree) stands to be a mangrove ecosystem as long as there was adequate tidal
exchange, propagule dispersal, and faunal interactions. We provide a ranking of
the important ecological functions, faunal groups, and impacts on mangroves.
Degradation due to development was identified as having the largest impact on
mangroves globally in terms of spatial scale, intensity, and time needed for restoration.
The results indicate that mangroves are ecologically unique even
though they may be species poor (from the vegetation perspective). The consensus
list of mangrove species and the ranking of the mangrove ecological
functions could be a useful tool for restoration and management of mangroves.
While there is ample literature on the destruction of mangroves due to aquaculture
in the past decade, this study clearly shows that more attention must go to avoiding and mitigating mangrove loss due to coastal development (such as
building of roads, ports, or harbors).
Research Interests:
The valuation of ecosystem services is a complex process as it includes several dimensions (ecological, socio-cultural and economic) and not all of these can be quantified in monetary units. The aim of this paper is to conduct an... more
The valuation of ecosystem services is a complex process as it includes several dimensions (ecological, socio-cultural and
economic) and not all of these can be quantified in monetary units. The aim of this paper is to conduct an ecosystem
services valuation study for mangroves ecosystems, the results of which can be used to inform governance and
management of mangroves. We used an expert-based participatory approach (the Delphi technique) to identify, categorize
and rank the various ecosystem services provided by mangrove ecosystems at a global scale. Subsequently we looked for
evidence in the existing ecosystem services literature for monetary valuations of these ecosystem service categories
throughout the biogeographic distribution of mangroves. We then compared the relative ranking of ecosystem service
categories between the monetary valuations and the expert based analysis. The experts identified 16 ecosystem service
categories, six of which are not adequately represented in the literature. There was no significant correlation between the
expert based valuation (the Delphi technique) and the economic valuation, indicating that the scope of valuation of
ecosystem services needs to be broadened. Acknowledging this diversity in different valuation approaches, and developing
methodological frameworks that foster the pluralism of values in ecosystem services research, are crucial for maintaining
the credibility of ecosystem services valuation. To conclude, we use the findings of our dual approach to valuation to make
recommendations on how to assess and manage the ecosystem services provided by mangrove ecosystems
economic) and not all of these can be quantified in monetary units. The aim of this paper is to conduct an ecosystem
services valuation study for mangroves ecosystems, the results of which can be used to inform governance and
management of mangroves. We used an expert-based participatory approach (the Delphi technique) to identify, categorize
and rank the various ecosystem services provided by mangrove ecosystems at a global scale. Subsequently we looked for
evidence in the existing ecosystem services literature for monetary valuations of these ecosystem service categories
throughout the biogeographic distribution of mangroves. We then compared the relative ranking of ecosystem service
categories between the monetary valuations and the expert based analysis. The experts identified 16 ecosystem service
categories, six of which are not adequately represented in the literature. There was no significant correlation between the
expert based valuation (the Delphi technique) and the economic valuation, indicating that the scope of valuation of
ecosystem services needs to be broadened. Acknowledging this diversity in different valuation approaches, and developing
methodological frameworks that foster the pluralism of values in ecosystem services research, are crucial for maintaining
the credibility of ecosystem services valuation. To conclude, we use the findings of our dual approach to valuation to make
recommendations on how to assess and manage the ecosystem services provided by mangrove ecosystems
Research Interests:
Research Interests:
AimTo reassess the capacity of mangroves for ecosystem services in the light of recent data.To reassess the capacity of mangroves for ecosystem services in the light of recent data.LocationGlobal mangrove ecosystems.Global mangrove... more
AimTo reassess the capacity of mangroves for ecosystem services in the light of recent data.To reassess the capacity of mangroves for ecosystem services in the light of recent data.LocationGlobal mangrove ecosystems.Global mangrove ecosystems.MethodsWe review four long-standing roles of mangroves: (1) carbon dynamics – export or sink; (2) nursery role; (3) shoreline protection; (4) land-building capacity. The origins of pertinent hypotheses, current understanding and gaps in our knowledge are highlighted with reference to biogeographic, geographic and socio-economic influences.We review four long-standing roles of mangroves: (1) carbon dynamics – export or sink; (2) nursery role; (3) shoreline protection; (4) land-building capacity. The origins of pertinent hypotheses, current understanding and gaps in our knowledge are highlighted with reference to biogeographic, geographic and socio-economic influences.ResultsThe role of mangroves as C sinks needs to be evaluated for a wide range of biogeographic regions and forest conditions. Mangrove C assimilation may be under-estimated because of flawed methodology and scanty data on key components of C dynamics. Peri-urban mangroves may be manipulated to provide local offsets for C emission. The nursery function of mangroves is not ubiquitous but varies with spatio-temporal accessibility. Connectivity and complementarity of mangroves and adjacent habitats enhance their nursery function through trophic relay and ontogenetic migrations. The effectiveness of mangroves for coastal protection depends on factors at landscape/geomorphic to community scales and local/species scales. Shifts in species due to climate change, forest degradation and loss of habitat connectivity may reduce the protective capacity of mangroves. Early views of mangroves as land builders (especially lateral expansion) were questionable. Evidence now indicates that mangroves, once established, directly influence vertical land development by enhancing sedimentation and/or by direct organic contributions to soil volume (peat formation) in some settings.The role of mangroves as C sinks needs to be evaluated for a wide range of biogeographic regions and forest conditions. Mangrove C assimilation may be under-estimated because of flawed methodology and scanty data on key components of C dynamics. Peri-urban mangroves may be manipulated to provide local offsets for C emission. The nursery function of mangroves is not ubiquitous but varies with spatio-temporal accessibility. Connectivity and complementarity of mangroves and adjacent habitats enhance their nursery function through trophic relay and ontogenetic migrations. The effectiveness of mangroves for coastal protection depends on factors at landscape/geomorphic to community scales and local/species scales. Shifts in species due to climate change, forest degradation and loss of habitat connectivity may reduce the protective capacity of mangroves. Early views of mangroves as land builders (especially lateral expansion) were questionable. Evidence now indicates that mangroves, once established, directly influence vertical land development by enhancing sedimentation and/or by direct organic contributions to soil volume (peat formation) in some settings.Main conclusionsKnowledge of thresholds, spatio-temporal scaling and variability due to geographic, biogeographic and socio-economic settings will improve the management of mangrove ecosystem services. Many drivers respond to global trends in climate change and local changes such as urbanization. While mangroves have traditionally been managed for subsistence, future governance models must involve partnerships between local custodians of mangroves and offsite beneficiaries of the services.Knowledge of thresholds, spatio-temporal scaling and variability due to geographic, biogeographic and socio-economic settings will improve the management of mangrove ecosystem services. Many drivers respond to global trends in climate change and local changes such as urbanization. While mangroves have traditionally been managed for subsistence, future governance models must involve partnerships between local custodians of mangroves and offsite beneficiaries of the services.