Elsevier

Ecosystem Services

Volume 25, June 2017, Pages 89-105
Ecosystem Services

Rapid Assessment of Wetland Ecosystem Services (RAWES): An example from Colombo, Sri Lanka

https://doi.org/10.1016/j.ecoser.2017.03.024Get rights and content

Highlights

  • The paper presents a rapid approach to the assessment of wetland benefits.

  • The utility of the approach is evaluated against other assessment methods.

  • A case study is provided from the wetlands of Metropolitan Colombo, Sri Lanka.

  • The example shows how wetland ecosystem services can be analysed and interpreted.

Abstract

Wetlands make essential positive contributions to multiple dimensions of human wellbeing. However, recognition of these benefits is often lacking in decision-making, compromising the wellbeing of both the ecosystem and is many linked human beneficiaries. Wetland site managers, decision-makers and stakeholders all need to better understand the benefits provided by wetlands. Despite a plethora of available assessment techniques, very few approaches are genuinely rapid, applicable across different wetland types or consider the realities of time and money resource constraints. The Rapid Assessment of Wetland Ecosystem Services (RAWES) approach is presented as a method that meets these needs, illustrated through its practical application in over 60 different wetland sites supporting development of a Wetland Strategy for the Metro Colombo Region, Sri Lanka. The approach is based on the trained, local assessors using a variety of field indicators in order to assess the positive or negative contribution over 30 wetland ecosystem services provide at local, regional or global scales. Outputs are simplified, signalling to decision-makers the diversity of interlinked ecosystem service outcomes consequent from management policies and actions.

Introduction

Wetland ecosystems are essential to human well-being (Millennium Ecosystem Assessment, 2005; Russi et al., 2013). A substantial body of evidence demonstrates that wetlands can deliver a great variety of benefits to human society (Ghermandi et al., 2010). These benefits include, but are not limited to, managing flood risk (Mitsch and Day, 2006), decreasing peak air temperatures (Sun et al., 2012), improving water quality (Shutes, 2001, Dhote and Dixit, 2009), protecting coastal communities from storms (Gedan et al., 2011), supporting food production (Lannas and Turpie, 2009, Verhoeven and Setter, 2009), providing vital cultural resources (McGregor et al., 2010) and offering locations for a variety of education and recreation opportunities (Cachelin et al., 2009, Finlayson et al., 2013).

Despite the acknowledged importance of wetlands, their values are routinely overlooked (McInnes, 2013a) or underestimated (Turner et al., 2008). They are commonly poorly considered in decision-making (Faulkner, 2004, Russi et al., 2013), resulting in continued loss and degradation of wetlands and their services (Davidson, 2014). One approach to stemming this loss is to adequately identify and value the ecosystem services that wetlands provide (Maltby and Ormerod, 2011, McInnes, 2013b) and to integrate the values of these services into decision-making frameworks (Hein et al., 2006, Daily and Matson, 2008).

A burgeoning body of research (Vihervaara et al., 2010, Milcu et al., 2013) and a vast array of evaluation approaches are available to identify, characterize and value ecosystem services (Waage and Stewart, 2008). A review by Bagstad et al., (2013) considered 17 different tools that assess, quantify, model, value and/or map ecosystem services. This review was not exhaustive and numerous other approaches are available for use by academics, private and public bodies and wetland managers (such as those by Maltby, 2009, OGP/IPIECA, 2011, WBCSD, 2011, Stratford et al., 2011, Maes et al., 2012, Everard and Waters (2013) and Peh et al., (2013) to name a few). All of these approaches differ in their application and scope, with many tools being limited in their utility as a result of high time, cost or data requirements rendering their wider uptake unlikely (Bagstad et al., 2013). A further criticism levelled at numerous assessment approaches is the failure to consider adequately spatial and temporal scales of benefits and the nature of the actual beneficiaries (Hein et al., 2006). Furthermore, many approaches pursue an economic valuation of ecosystem services in the hope that it can provide conservation practitioners with a “silver bullet” (Vira and Adams, 2009). Often, advocates of these simplified economic approaches fail to acknowledge that derived monetary values are not robust, the assumptions upon which they are based are munificent and that the output numbers will only represent a snapshot that will inevitably vary in space and time (Spangenberg and Settele, 2010). Such limitations are not new and, in a widely-acknowledged seminal study, Costanza et al., (1997) emphasised such approximations and discrepancies in estimating the value of global natural capital.

A common significant oversight is the inability of these multiple approaches to take a systemic view of the plurality of values provided by wetland ecosystems (Everard and McInnes, 2013). They thereby tend to emphasise a limited subset of benefits which in turn reflects a reductive, discipline-bound and legislatively-constrained paradigm (Everard, 2016). As an antidote to many of the published approaches, The Economics of Ecosystems and Biodiversity (TEEB) study advocates a tiered or hierarchical approach which seeks to recognize, demonstrate and capture the value of the services (TEEB, 2010). Under some circumstances, the ability to simply recognize value may be sufficient to highlight important ecosystem services; monetary valuation may be unnecessary, or even counterproductive, if it is seen as contrary to cultural norms or fails to reflect a plurality of social values (Defra, 2007, TEEB, 2010). Furthermore, the under-recognition of wetland ecosystem services undermines biodiversity conservation arguments, weakens the case for protection or restoration, and ultimately impacts on human well-being (McInnes, 2013a).The recognition of benefits sensu TEEB (2010) can be achieved through field observation, re-assembling expert and indigenous knowledge, processing published information and/or through dialogue with relevant stakeholders (Wattage and Mardle, 2005, McInnes et al., 2016a). Such a qualitative or relative assessment approach has been explicitly advocated to demonstrate the value of wetland ecosystems (Russi et al., 2013). Whilst there is an inherent uncertainty in taking this heuristic approach, significant merit remains by providing an overview of the multiplicity of values for any wetland area (McInnes, 2013a). The outputs from such a process can provide a qualitative or relative assessment of the range of ecosystem services provided by a wetland and a rapid and comprehensive overview of the various benefits provided by wetlands across a large geographic area.

This paper reviews the Rapid Assessment of Wetland Ecosystem Services (RAWES) approach. This is a technique that has been developed through an iterative process of field trials at numerous wetland sites in the United Kingdom, India, Chad and Ireland, in considerations of approaches to urban drainage (Everard et al., 2016) and through dialogue with stakeholders and potential end-users such as site managers, academics, non-governmental organisations and intergovernmental bodies, such as the Ramsar Convention. The approach seeks to address the genuine resource (time and financial) and data constraints faced by many wetland managers and also attempts to resolve issues relating to scale and the scope of beneficiaries. Results from an extensive field trial undertaken across the wetlands of urban Colombo, Sri Lanka, are presented in order to evaluate the utility, reliability and application of the RAWES approach.

Section snippets

Need and purpose

The Ramsar Convention provides a framework for international cooperation and national action for the conservation and wise use of wetlands (Gardner and Davidson, 2011). A review of how the Convention reports on ecosystem services demonstrated that there are significant differences among the reporting on ecosystem services and that comprehensive assessments of Ramsar Sites and wider wetlands are poor (McInnes et al., 2016b). This review echoed findings from elsewhere which demonstrate a bias

The wetlands of Colombo

Wetlands in Sri Lanka, both natural and man-made, have been at the centre of civilisation across the island for more than two thousand years (Zon, 2004) and continue to provide a range of critical benefits to society today (Sellamuttu et al., 2011). The capital city, Colombo, is subject to a rapid pace of development which is leading to wetland loss and degradation. Between 1981 and 2008, in some areas of the city, 43% of former paddy lands have been converted to non-wetland (Hettiarachchi et

Characterisation of field assessment sites

Based on the hydrological modelling conducted as part of the larger study (McInnes et al., 2016c), a distinction was made between wetland areas that are influenced by tidal water level fluctuations (n = 35; 56.5% of field assessment sites) and those that are beyond the physical influence of tides (n = 27; 43.5%) (Fig. 1). Within the tidal area, salinity broadly increases towards the coast and along the main surface water carriers in the drainage system. None of the field assessment sites were

Is the approach ‘rapid’?

Wetland decision-makers, and especially those in poorly resourced parts of the world, need simple, user-friendly, cost-effective tools that enable them to systematically understand and protect wetlands and the important ecosystem services they provide (Carletti et al., 2004, McInnes et al., 2016b). Numerous techniques exist for assessing the benefits provided by wetlands. Fennessy et al. (2007) reviewed more than 40 and Bagstad et al. (2013) evaluated 17 different ecosystem services assessment

Acknowledgements

The field assessments were conducted as part of the World Bank funded Metro Colombo Urban Development Project (MCUDP/PHRD/03) under “The consultancy services for the preparation of a management strategy for wetlands and carrying out an assessment of water quality in the inland waterways and lakes within Metro Colombo area”. The authors would like to thank the lead consultants – Signes along with all the other consultants that worked on the wider project, as well as staff from the Sri Lanka Land

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