Participatory Approaches to Ecosystem Service Assessment

An important component of my project is the involvement of stakeholders in creating the scenarios for 2050. Hopefully my connections with the Welland Rivers Trust and Welland Valley Partnership will enable me to interact with a diverse range of stakeholders; but why bother?

With the rapidly expanding capability to model ecosystem services comes a set of ‘caveats’ or ‘responsibilities’ that the modeller must keep in mind in order for the assessments to be meaningful (Daily et al. 2009). Chief amongst these is the necessity to include the ‘human’ factor (Turner et al. 2016).

Deterministic and process based models such as InVEST and LUCI are incredibly powerful tools for creating spatially explicit output on the condition and value of ecosystem services (Bagstad et al. 2013, Sharps et al. 2017). But, despite much valuable work having been completed using these models Turner et al. (2016) still identify a significant knowledge gap in terms of assessing the social context along with the human demand for services. The challenge for researchers is to move away from the top left corner of figure 1 and move towards to centre / bottom right.

Microsoft Word - ManusECOLMOD2
Figure 1 – Taken from Turner et al. (2016): The socio-ecological system and ecosystem service modelling.

This is no easy task, but one way of making progress in this area, specific to studies that model alternative futures, is to involve stakeholders in the creation of scenarios (Turner et al. 2016). This is the exact approach I will be taking in my project. It is always validating (and encouraging) when you find support for your methods in the literature! The final word from Turner et al. (2016).

“Participatory modeling in this context is a powerful tool of stakeholder capacity building and an instrument for ‘leveling the playing field’ that creates potential for consensus and trust”

 

References

Bagstad, K.J., Semmens, D.J. and Winthrop, R. (2013) ‘Comparing approaches to spatially explicit ecosystem service modeling: A case study from the San Pedro River, Arizona’, Ecosystem Services, 5, pp. 40-50

Daily, G.C., Polasky, S., Goldstein, J., Kareiva, P.M., Mooney, H.A., Pejchar, L., Ricketts, T.H., Salzman, J. and Shallenberger, R. (2009) ‘Ecosystem Services in Decision Making: Time to Deliver’, Frontiers in Ecology and the Environment, 7(1), pp. 21-28

Sharps, K., Masante, D., Thomas, A., Jackson, B., Redhead, J., May, L., Prosser, H., Cosby, B., Emmett, B. and Jones, L. (2017) ‘Comparing strengths and weaknesses of three ecosystem services modelling tools in a diverse UK river catchment’, Science of The Total Environment, 584–585, pp. 118-130

Turner, K.G., Anderson, S., Gonzales-Chang, M., Costanza, R., Courville, S., Dalgaard, T., Dominati, E., Kubiszewski, I., Ogilvy, S., Porfirio, L., Ratna, N., Sandhu, H., Sutton, P.C., Svenning, J., Turner, G.M., Varennes, Y., Voinov, A. and Wratten, S. (eds.) (2016) A review of methods, data, and models to assess changes in the value of ecosystem services from land degradation and restoration. Ecological Modelling, 319, p. 190-207

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Wrestling with vocabulary

During my PhD I am aiming to develop a method that can analyse the trade-offs in ecosystem services for the Welland Catchment under different scenarios of landscape change. It’s great to finally be under way! I’ve got a lot to get on with including brushing up on my ‘R’ skills and learning Python (eeek!).

Alongside these technical issues I’ve also resumed my tussle with the literature.  I’d made a good start on this when preparing the proposal for the project but I’ve recently focused on some new areas to explore.

An important debate around my project centres on the confusion amongst policy makers regarding what exactly is meant by natural capital, ecosystem functions and ecosystem services as well as how these terms are connected. Turner et al. (2016) deals with this well. A current obstacle to achieving human well-being in a sustainable way has been a lack of understanding of these terms (by the well intentioned) combined with a reluctance to accept and adpot them (by the less well intentioned (my opinion!)).

The MEA helped redress this, making the concepts mainstream; but there is still a great deal of confusion. Here is a neat little diagram effectively explaining the relationship between these tricky concepts, taken from Turner et al. (2016).

Microsoft Word - ManusECOLMOD2

First it will be useful to define these terms, which Turner et al. (2016) can help us with again:

Natural Capital – the natural world and its ecosystems. Anything that does not require human agency to produce or maintain

Social Capital – the societal networks and norms that facilitate co-operative action i.e. cultures, institutions and the economic system

Human Capital – individual peoples, including knowledge and information stored in our brains, our physical health and are ability to perform labour

Built Capital – manufactured goods, such as tools, as well as infrastructure such as roads and buildings

With these definitions in mind the connection between the different forms of capital and humanity’s well-being become clearer. Natural capital produces everything that humanity relies upon. This is why all other forms of capital are shown within the green circle. Ecosystem functions are the processes and mechanisms that keep natural capital ticking i.e. pollination, predation, decomposition, the carbon and nutrient cycles…

The benefits to humanity that natural capital and ecosystem functions produce are seen on the diagram as a capital flow and are termed ecosystem services. These interact with all other forms of capital flow to produce the benefits that natural capital provides us. Sustainability comes into the equation when you understand that the boundary around natural capital is a hard limit. Natural capital’s stock is finite and social capital cannot expand beyond these limits. Although natural capital has some ability to repair and regenerate itself, the ecosystem functions underpinning this ability are often fragile and not fully understood. When social capital functions within these bounds sustainability is a realistic objective.

Methods to assess how changes to policy and the landscape influence the capital flow of ecosystem services (such as the toolkit I am developing) will hopefully provide policy makers with better information in order to achieve more sustainable decisions.

 

References

Turner, K.G., Anderson, S., Gonzales-Chang, M., Costanza, R., Courville, S., Dalgaard, T., Dominati, E., Kubiszewski, I., Ogilvy, S., Porfirio, L., Ratna, N., Sandhu, H., Sutton, P.C., Svenning, J., Turner, G.M., Varennes, Y., Voinov, A. and Wratten, S. (eds.) (2016) A review of methods, data, and models to assess changes in the value of ecosystem services from land degradation and restoration. Ecological Modelling, 319, p. 190-207

Analysing Ecosystem Services – InVEST’s Carbon Module

In a previous post I discussed the growth of the concept of ecosystem services (ES), thanks in part to large scale studies such as the Millennium Ecosystem Assessment. It is undoubtedly an attractive concept to both conservationists and policy makers alike who can see its value in both promoting conservation policies and measuring their potential benefits (Goldstein et al. 2012).

The growing availability of software that is able to quantify and visualise the provision or value of ES has been crucial to its development as a cornerstone of how socio-ecological interactions are defined and analysed (Bagstad et al. 2013, Daily et al. 2009, Harmackova and Vackar, 2015).

An example of such software is InVEST (Integrated Valuation of Ecosystem Services and Trade-offs). InVEST will play a crucial part in the analysis for my thesis and is a widely used tool in the field of ES analysis. InVEST’s freely available models rely primarily on the input of geo-referenced land use / land cover (LULC) information combined with biophysical functions defined by the user. Some of its models are more complex and involve spatial analytical elements such as distance to potential threats (habitat quality) or flow direction (water quality) but InVEST’s carbon module is relatively simple. Each LULC class is assigned a carbon value for four pools (above and below ground biomass, soil and dead organic matter) and the total stores of carbon are aggregated based on the area of each class in the LULC raster (Sharp et al. 2016). While this might seem simple enough, the output of this model has been used in a wide variety of analyses, carbon storage and sequestration being one of the most studied and analysed ES (Ayanu et al. 2012). The table below outlines the diversity of applications of InVEST’s carbon module in the literature.

Author(s) How was InVEST used?
Sharps et al. (2017) Analysed ES provision from afforestation scenarios. Also compared the accuracy of InVEST with LUCI and ARIES, other examples of ES modelling software.
Bottalico et al. (2016) Quantified the potential impact of various forestry policies on timber production and carbon storage.
Cabral et al. (2016) Quantified the change in ES provision for a mixed urban / rural region based on past land cover change.
He et al. (2016) Combined InVEST with an econometric model of urban growth to analyse how urbanisation scenarios might affect carbon storage and sequestration.
Garrastazu et al. (2015) Modelled the potential impact on ES provision resulting from changes to legislation for vegetative riparian buffers.
Chaplin-Kramer et al. (2015) Modelled different spatial patterns of deforestation and used InVEST to assess ES provision of resulting land covers.
Harmackova and Vackar (2015) Modelled various conservation scenarios for a wetland landscape and assessed ES provision of the resulting landscapes.
Keller et al. (2015) The output of InVEST’s carbon module was used in a multi criteria analysis, selecting optimal sites for new shale gas wells.
Tao et al. (2015) Used InVEST to estimate carbon stocks along an urbanisation gradient.
Lawler et al. (2014) Analysed ES provision for national landscape change scenarios; modelled econometrically based on socio-economic drivers of change.
Bhagabati et al. (2014) Assessed ES provision for different landscapes resulting from various conservation scenarios for rare Sumatran tiger habitat.
Bagstad, Semmens and Winthrop (2013) Compared with output from ARIES in an assessment of the accuracy of ES modelling software.
Delphin et al. (2013) Assessed the potential damage hurricanes might cause to the timber industry and the ES of carbon storage.
Kovacs et al. (2013) Output from InVEST models used in return on investment calculations for society, based on potential landscape scale conservation initiatives.
Liu et al. (2013) Output included in a multi criteria analysis, defining priority areas for conservation based on their provision of ES.
Goldstein et al. (2012) Assessing the ES provision of future landscape scenarios in order to inform decision making for a private landowner.
Izquierdo and Clark (2012) Provided input to decision support software to aid in the prioritisation of conservation planning.
Bai et al. (2011) Used InVEST output in an assessment of the spatial relationship between ES and biodiversity.
Polasky et al. (2011) InVEST was used to quantify changes in ES, habitat quality and returns to landowners for LULC change in Minnesota between 1992-2001.
Nelson et al. (2010) InVEST output used to assess the impact of various 2000-2015 change scenarios on global ES provision.

There are of course limitations to InVEST’s carbon module. For one it is highly dependent on the scale and quality of the LULC data in the model as well as the accuracy of carbon pools used to calibrate it (Sharps et al. 2017). The field is aware of this and identifies the development of spatially explicit archives as a key goal in developing ES modelling (Bagstad et al. 2013, Chaplin-Kramer et al. 2015). Keller et al. (2015) directly counter this limitation, explaining that if InVEST’s output is used more as an indicator of the potential magnitude and direction of change in ES provision, then issues around the accuracy of model output can be somewhat overlooked. Unless the data that has parameterised the model is of exceptional quality using InVEST to quantify absolute values of ES may bring validity issues (Keller et al. 2015).

Other problems lie in the simplicity of InVEST’s approach to modelling the flux of carbon sequestration. Unless there has been no change in LULC class between years then the model assumes a stable state of carbon storage. This of course completely ignores important biogeochemical and ecological process that can affect the value and flow of carbon between pools (Cabral et al. 2016).

Despite these limitations InVEST remains a widely used toolkit for ES analysis. It is freely available and has relatively low data demands; lots of default biophysical values are even included in the models should the user wish to make use of them. It has been shown to improve stakeholder engagement and understanding in the concept of ES and positively effect decision making (Bhagabati et al. 2014). ES analysis is becoming a bigger part of policy and decision making. The use of easy to understand modelling tool kits that are simple to operate will be a major boon to conservation and sustainability especially as the users of these models refine and improve them (Bhagabati et al. 2014, Cabral et al. 2016).

 

References

Ayanu, Y.Z., Conrad, C., Nauss, T., Wegmann, M. and Koellner, T. (2012) ‘Quantifying and mapping ecosystem services supplies and demands: a review of remote sensing applications’, Environmental science & technology, 46(16), pp. 8529

Bagstad, K.J., Semmens, D.J. and Winthrop, R. (2013) ‘Comparing approaches to spatially explicit ecosystem service modeling: A case study from the San Pedro River, Arizona’, Ecosystem Services, 5, pp. 40-50.

Bai, Y., Zhuang, C., Ouyang, Z., Zheng, H. and Jiang, B. (2011) ‘Spatial characteristics between biodiversity and ecosystem services in a human-dominated watershed’, Ecological Complexity, 8(2), pp. 177-183.

Bhagabati, N.K., Ricketts, T., Sulistyawan, T.B.S., Conte, M., Ennaanay, D., Hadian, O., McKenzie, E., Olwero, N., Rosenthal, A. and Tallis, H. (2014) ‘Ecosystem services reinforce Sumatran tiger conservation in land use plans’, Biological Conservation, 169, pp. 147-156.

Bottalico, F., Pesola, L., Vizzarri, M., Antonello, L., Barbati, A., Chirici, G., Corona, P., Cullotta, S., Garfì, V. and Giannico, V. (2016) ‘Modeling the influence of alternative forest management scenarios on wood production and carbon storage: A case study in the Mediterranean region’, Environmental research, 144, pp. 72-87.

Cabral, P., Feger, C., Levrel, H., Chambolle, M. and Basque, D. (2016) ‘Assessing the impact of land-cover changes on ecosystem services: a first step toward integrative planning in Bordeaux, France’, Ecosystem Services, 22, pp. 318-327.

Daily, G.C., Polasky, S., Goldstein, J., Kareiva, P.M., Mooney, H.A., Pejchar, L., Ricketts, T.H., Salzman, J. and Shallenberger, R. (2009) ‘Ecosystem Services in Decision Making: Time to Deliver’, Frontiers in Ecology and the Environment, 7(1), pp. 21-28.

Delphin, S., Escobedo, F., Abd-Elrahman, A. and Cropper, W. (2013) ‘Mapping potential carbon and timber losses from hurricanes using a decision tree and ecosystem services driver model’, Journal of environmental management, 129, pp. 599-607.

Garrastazú, M.C., Mendonça, S.D., Horokoski, T.T., Cardoso, D.J., Rosot, M.A., Nimmo, E.R. and Lacerda, A.E. (2015) ‘Carbon sequestration and riparian zones: Assessing the impacts of changing regulatory practices in Southern Brazil’, Land Use Policy, 42, pp. 329-339.

Goldstein, J.H., Caldarone, G., Thomas, K.D., Ennaanay, D., Hannahs, N., Mendoza, G., Polasky, S., Wolny, S. and Daily, G.C. (2012) ‘Integrating ecosystem- service tradeoffs into land- use decisions’, Proceedings of the National Academy of Sciences, 109(19), pp. 7565.

Harmáčková, Z.V. and Vačkář, D. (2015) ‘Modelling regulating ecosystem services trade-offs across landscape scenarios in Třeboňsko Wetlands Biosphere Reserve, Czech Republic’, Ecological Modelling, 295, pp. 207-215.

He, C., Zhang, D., Huang, Q. and Zhao, Y. (2016) ‘Assessing the potential impacts of urban expansion on regional carbon storage by linking the LUSD-urban and InVEST models’, Environmental Modelling & Software, 75, pp. 44-58.

Izquierdo, A.E. and Clark, M.L. (2012) ‘Spatial analysis of conservation priorities based on ecosystem services in the Atlantic forest region of Misiones, Argentina’, Forests, 3(3), pp. 764-786.

Keller, A.A., Fournier, E. and Fox, J. (2015) ‘Minimizing impacts of land use change on ecosystem services using multi-criteria heuristic analysis’, Journal of environmental management, 156, pp. 23-30.

Kovacs, K., Polasky, S., Nelson, E., Keeler, B.L., Pennington, D., Plantinga, A.J. and Taff, S.J. (2013) ‘Evaluating the return in ecosystem services from investment in public land acquisitions’, PloS one, 8(6), pp. e62202.

Lawler, J.J., Lewis, D.J., Nelson, E., Plantinga, A.J., Polasky, S., Withey, J.C., Helmers, D.P., Martinuzzi, S., Pennington, D. and Radeloff, V.C. (2014) ‘Projected land-use change impacts on ecosystem services in the United States’, Proceedings of the National Academy of Sciences of the United States of America, 111(20), pp. 7492-7497.

Liu, Y., Zhang, H., Yang, X., Wang, Y., Wang, X. and Cai, Y. (2013) ‘Identifying priority areas for the conservation of ecosystem services using GIS-based multicriteria evaluation’, Pol.J.Ecol, 61(3), pp. 415-430.

Nelson, E., Sander, H., Hawthorne, P., Conte, M., Ennaanay, D., Wolny, S., Manson, S. and Polasky, S. (2010) ‘Projecting global land-use change and its effect on ecosystem service provision and biodiversity with simple models’, PloS one, 5(12), pp. e14327.

Polasky, S., Nelson, E., Pennington, D. and Johnson, K.A. (2011) ‘The impact of land-use change on ecosystem services, biodiversity and returns to landowners: A case study in the State of Minnesota’, Environmental and Resource Economics, 48(2), pp. 219-242.

Sharp, R., Tallis, H.T., Ricketts, T., Guerry, A.D., Wood, S.A., Chaplin-Kramer, R., Nelson, E., Ennaanay, D., Wolny, S., Olwero, N., Vigerstol, K., Pennington, D., Mendoza, G., Aukema, J., Foster, J., Forrest, J., Cameron, D., Arkema, K., Lonsdorf, E., Kennedy, C., Verutes, G., Kim, C.K., Guannel, G., Papenfus, M., Toft, J., Marsik, M., Bernhardt, J., Griffin, R., Glowinski, K., Chaumont, N., Perelman, A., Lacayo, M. Mandle, L., Hamel, P., Vogl, A.L., Rogers, L., Bierbower, W., Denu, D., and Douglass, J. 2016. InVEST +VERSION+ User’s Guide. The Natural Capital Project, Stanford University, University of Minnesota, The Nature Conservancy, and World Wildlife Fund.

Sharps, K., Masante, D., Thomas, A., Jackson, B., Redhead, J., May, L., Prosser, H., Cosby, B., Emmett, B. and Jones, L. (2017) ‘Comparing strengths and weaknesses of three ecosystem services modelling tools in a diverse UK river catchment’, Science of The Total Environment, 584–585, pp. 118-130.

Tao, Y., Li, F., Liu, X., Zhao, D., Sun, X. and Xu, L. (2015) ‘Variation in ecosystem services across an urbanization gradient: A study of terrestrial carbon stocks from Changzhou, China’, Ecological Modelling, 318, pp. 210-216.

Selling nature to save it

Why should we make an effort to conserve ‘nature’?

This is a question that loomed large in a lot of the material I engaged with whilst studying for my Master’s degree. As I begin a PhD in which I will explicitly analyse the ‘value’ of the landscape of the catchment of the River Welland, it is a question I find myself returning to (see my ‘about me’ page for details of my project). What are the next four years of effort going to amount to? What is the significance of the work that I will produce and why is it worth investing in?

Reflecting on these questions I feel the need to first establish one definition of what I mean by nature. As someone who subscribes to ecological theory I find it useful to think of nature in terms of communities; ‘ecosystems’, consisting of the plants, animals and the physical environments that they inhabit. Between these three components exists flows of material and energy, as well as intra and interspecific interactions.

The healthy functioning of ecosystems provide us, human beings, with a host of ‘ecosystem services’. Ecosystem services are defined as “the direct and indirect contributions of ecosystems to human wellbeing” (TEEB, 2016). The Millennium Ecosystem Assessment (MEA), published in 2005 took “a giant step forward in developing a widely shared vision” of the pressure that these services are under (Kareiva, 2011 p.5) and categorised these services as supporting, regulating, cultural and provisioning services.

ESs

The MEA (2005) helped mainstream the concept of ecosystem services and bring it beyond academia into the spheres of governance and industry (De Groot et al. 2010). Some would argue that ecosystem services make the valuation of nature more tangible (Daily et al. 2009, Kareiva, 2011, Costanza et al. 1997) and that if we can conceptualise the benefits that functioning ecosystems create for us we may be more inclined to protect them. Daily et al. (2009) comment that the concept of ecosystem services are one of our best hopes for making conservation mainstream and that the vision of the MEA (2005) is of a world where people and institutions appreciate nature as an asset; subsequently making more sustainable decisions regarding its use. This approach to conservation, founded on the concept of ecosystem services, places great emphasis on the instrumental value of nature.

Arguments such as this inspired the title of this post, is such an approach to conservation selling nature to save it? One interpretation of the concept of ecosystem services is that it commodifies nature (Portman, 2013). Indeed many contemporary conservation strategies work in this way; through establishing payments for ecosystem services (PES). PES, in its ideal form (as defined by environmental economists), is a voluntary payment from the user to the provider of an environmental service conditional on satisfactory provision, the aim of which is to internalise environmental externalities to achieve market efficiency and reduce degradation of the environment (Wunder, 2005, Kosoy and Corbera, 2010, Pasucal et al., 2010). One of the longest running and best known PES schemes is the ‘Pago por Servicios Ambientales’ (PSA) from Costa Rica which is often discussed as a triumph of market based approaches to conservation and resource management (Pagiola, 2008, Fletcher and Breitling, 2012).

This approach is not without its critics who worry that the neoliberalisation of environmental management will create more problems than it solves (Matulis, 2014, Redford and Adams, 2009). It could be argued that PES evolved from a growth mind-set, that continuous economic growth is possible and desirable. Economic justifications for environmental management will always be convincing because of the prevalence of this way of thinking but until concerns with growth and efficiency are muted we will be inadequately positioned to effectively manage our environmental resources. What I believe must gain more prevalence is an appreciation of the intrinsic value of nature. In ‘A Sand County Almanac’ a book that I always return to, Aldo Leopold wrote:

“That land is a community is the basic concept of ecology, but that land is to be loved and respected is an extension of ethics” – Leopold (1948) p. xiii

This ‘land ethic’ perfectly encapsulates to me why conservation is necessary.  We should seek to conserve and protect nature because we have an ethical duty to do so, it is the ‘right thing to do’. It is possible to frame nature in terms of the tangible benefits that it provides us (in fact this is often a useful way to demonstrate the value of conservation to those with the power to act upon it) but it should not be the driving motivation for conservation. Nature has an intrinsic value that transcends any effort on our part to account for its instrumental value.

The ontology of sustainability is often presented as a Venn diagram with three overlapping circles of society, economy and the environment, with the sweet spot in the middle representing sustainable actions. To me this way of thinking has always reinforced the belief that humans exists outside of nature, that it is something to be balanced and ‘worked with’. I would argue that a more realistic ontological hierarchy, in terms of the importance of nature and our relationship with it is as below:

ontology

Nature is the most important component of this ontology, and EVERYTHING depends on a healthy, functioning environment. Nothing exists, can function or grow outside of environmental limits. This is the mind-set that I wish was dominant amongst politicians and the people with power.

My belief that the intrinsic value of nature trumps any attempt to quantify its instrumental value means that I will always grapple with the concept of ecosystem services; even as I begin a PhD where the quantitative analysis of ecosystem services forms the central body of my work. By engaging with the concept and contributing to research in the field am I reinforcing some of the issues that I have raised in this post? Or am I engaging with the dominant paradigm because it is the best way to advance the beliefs and values that I hold most dear? Remaining reflective and critical will be a crucial part of navigating my PhD and I hope that posting regularly to this blog, exploring not just the technical and methodological questions of my work, but also the ethical, will make me a better researcher.

 

References (must reads in bold!)

Costanza, R., Farber, S., Naeem, S., Raskin, R.G., Sutton, P., de Groot, R., Limburg, K., Paruelo, J., van den Belt, M., Hannon, B., d’Arge, R., O’Neill, R.V. and Grasso, M. (1997) ‘The value of the world’s ecosystem services and natural capital’, Nature, 387(6630), pp. 253-260

Daily, G.C., Polasky, S., Goldstein, J., Kareiva, P.M., Mooney, H.A., Pejchar, L., Ricketts, T.H., Salzman, J. and Shallenberger, R. (2009) ‘Ecosystem Services in Decision Making: Time to Deliver’, Frontiers in Ecology and the Environment, 7(1), pp. 21-28

de Groot, R.S., Alkemade, R., Braat, L., Hein, L. and Willemen, L. (2010) ‘Challenges in integrating the concept of ecosystem services and values in landscape planning, management and decision making’, Ecological Complexity, 7(3), pp. 260-272

Fletcher, R. and Breitling, J. (2012) ‘Market mechanism or subsidy in disguise? Governing payment for environmental services in Costa Rica’, Geoforum, 43(3), pp. 402-411

Kareiva, P.M. (2011) Natural capital: theory & practice of mapping ecosystem services. Oxford: Oxford University Press

Kosoy, N. and Corbera, E. (2010) ‘Payments for ecosystem services as commodity fetishism’, Ecological Economics, 69(6), pp. 1228-1236

Leopold, A. (1948) ‘A Sand County Almanac – and Sketches Here and There’, Oxford University Press, New York

Matulis, B.S. (2014) ‘The economic valuation of nature: A question of justice?’, Ecological Economics, (104), pp. 155-157

Millennium Ecosystem Assessment. (2005) ‘Ecosystems and Human Wellbeing: Synthesis.’ Island Press. Washington, D.C

Pagiola, S. (2008) ‘Payments for environmental services in Costa Rica’, Ecological Economics, 65(4), pp. 712-724

Pasucal, U., Muradian, R., Rodríguez, L.C. and Duraiappah, A. (2010) ‘Exploring the links between equity and efficiency in payments for environmental services: A conceptual approach’, Ecological Economics, 69(6), pp. 1237-1244

Portman, M.E. (2013) ‘Ecosystem services in practice: Challenges to real world implementation of ecosystem services across multiple landscapes – A critical review’, Applied Geography, 45, pp. 185-192.

Redford, K.H. and Adams, W.M. (2009) ‘Payment for ecosystem services and the challenge of saving nature’, Conservation biology: the journal of the Society for Conservation Biology, 23(4), pp. 785-787

The Economics of Ecosystems and Biodiversity (TEEB) (2016), available at: http://www.teebweb.org/resources/glossary-of-terms/ (Accessed 10/04/2017)

Wunder, S. (2005) ‘Payments for ecosystem services: some nuts and bolts’ Occasional Paper No. 42 Centre for International Forestry Research, Nairobi, Kenya