Valuing wetland ecosystem services based on benefit transfer: A meta-analysis of China wetland studies

Highlights

• We conduct a meta-analysis of Chinese wetland valuation research during 2000–2017.

• We determine important factors that may impact wetland valuation results.

• Wetland size influences the wetland ecosystem service valuation results most.

• Value of wetlands and ecosystem service functions rise as wetland area increases.

• It is feasible to apply the meta-analysis results to benefit transfer.

Abstract

While wetlands contribute significantly to ecosystem services, their nature as a public good implies that the public sector, rather than the market, values their conservation, utilization, and trade-offs among various ecosystem services. Thus, the valuation of wetlands and their ecosystem services is important for policy makers. This study conducts a meta-analysis of valuation research on China’s wetlands based on 133 independent studies involving 146 cases published during 2000–2017. The study evaluates the weight of different factors in the existing valuation results, discusses the errors of benefit transfer, and applies the benefit transfer method to evaluate the ecosystem services of Yancheng wetland in Jiangsu province. The primary results are as follows. Wetland size influences wetland service valuation results most significantly. The value of all ecosystem services increases as wetland area increases with an average elasticity of 0.83. Factors such as economic and social development level, wetland type, research time, literature source, and valuation methods have impacts only on several individual service types. It is feasible to apply the meta-analysis results to benefit transfer. Compared with the per unit area value model, which is more stable in transfer errors, the wetland service value has better goodness of fit. Therefore,in conducting benefit transfer, the wetland service value models are suggested.

Introduction

Wetlands play pivotal roles in global biodiversity conservation, yet they are among the most threatened ecosystems on the planet. The nature of wetlands as a public good leads to their overuse and undervaluation, which further causes the loss of wetlands, increases their fragmentation, and seriously reduces their ecological functions. As such, the government and the public often have to face the trade-off between wetland exploitation and conservation. Thus, providing information and gaining a good understanding of the value of wetlands are very important for decision making and the policy implementation of conservation and sustainable management of wetlands (Van Asselen et al., 2013).

In recent years, with the vigorous development of overall assessments of the wetland ecosystem, research on wetland valuation has escalated (see Fig. 1). A preliminary search of “wetland” and “valuation” in the Web of Science database indicates that among 415 studies on wetland valuation published during 1975–2016, about 57.5% were published during 2011–2016. Results from these valuation studies could provide potentiallly useful references for wetland protection decisions. However, this flood of data has also generated confusion for policymakers about how to apply these valuation results to real world decision making. First, wetlands provide multiple ecological services, each of which can be valued in a different dimension. Thus, it is difficult to evaluate all wetland ecological services using a single method, and the attributes or dimensions involved in each valuation study also differ. Second, a variety of valuation methods have been applied to value wetland services, including contingent valuation method (CVM), travel cost method, hedonic pricing, production function approach, opportunity cost, and replacement cost, etc. Each method may be theoretically self-consistent and reasonable, but overall, valuation methods differ considerably in terms of the welfare measurement, potentially rendering their valuation results incomparable. Therefore, each method is generally context specific and does not provide a universal insight into the value of wetlands. Given such diversified estimates of value derived from different wetland types, ecosystem services, valuation methodologies and country origins, it is necessary to compile existing valuation results and identifies which are important factors that may have significant impacts on wetland valuation results, and how to apply the independent results to wetland management (Van den Bergh et al., 1997; Stanley, 2001; Brander et al., 2006; Meli et al., 2014).

The benefit transfer method based on meta-regression analysis can largely meet the aforementioned needs. Meta-regression analysis mainly discusses the influencing factors of the valuation results by modeling and analyzing original independent researches. Based on the regression analyses, the benefit transfer method further summarize the comprehensive research results to provide a benefit transfer model for estimating the value of target wetlands. Moreover, conducting independent valuation studies is often costly and time consuming, and cannot respond quickly to meet the requirements for fast assessment or evaluation of large-scale ecosystems in real world. Given these considerations, the benefit transfer method can serve as a more feasible alternative.

There are several related studies in the field of wetland valuation using meta-analysis and benefit transfer (see Table 1). Brouwer et al. (1999) initiated these efforts by focusing on temperate wetlands in developed countries (mainly the United States) and using CVM as the valuation method. Woodward and Wui’s (2001) research sample involved multiple valuation methods, including CVM, but mainly concentrated on wetlands on North America and Europe. Brander et al. (2006) covered a variety of valuation methods and wetlands in a wider geographic range in their meta-analysis, with main samples still concentrated on North America. Ghermandi et al. (2008) expanded their samples to cover Africa, Asia, and Europe, and included man-made wetlands for the first time. Zhang’s (2014) research (in Chinese) conducted a meta-regression on the evaluation results of the ecological service of lake and marsh wetlands in China, and transformed the results to a large-scale assessment of lake wetlands in China, while did not consider different evaluation methods and their impacts on the valuation results. Zhang et al.’s (2015) research (in Chinese) mainly focused on the evaluation of the value of lake wetlands in China while excluding man-made lake wetlands and not considering non-use values. Xu’s (2015) research (in Chinese) focused only on non-use valuation of China’s lakeside wetlands using CVM method. Despite existing studies mentioned above, it is still neccessary to further expand meta-analyses to cover more types of wetlands, more diversified valuation methods, and a wider geographical range. In addition, most meta-studies have focused mainly on assessing the total value of wetlands and its influencing factors, while the individual wetland service is discussed only insofar as its inclusion may affect the total value. In fact, the findings of individual wetland service value and its influencing factors provide rich information, as trade-offs may occur among various services.

In addition, we noticed a dearth of summaries on the large number of valuation results about China’s wetlands, although there existing an urgent need for such analysis from the policy decision perspective. China’s wetlands are important components of the global ecosystem, constituting 10% of the world’s total; China’s wetlands comprise a large area, are of many different types, and are widely distributed. However, in recent decades, with intensifying climate change and the acceleration of agricultural and urban expansion, China’s wetlands have suffered loss of ecological functions as well as declining economic value (Xu et al., 2014). To conserve these valuable wetlands, China has launched a series of wetland conservation, compensation, and restoration programs, which require more information about the value of wetland conservation to support relevant decisions.

China has accumulated a lot of primary empirical research in the field of wetland valuation. In order to enable these information to support the wetland conservation decisions, this study conducts a comprehensive quantitative summary of the existing valuation research results of China’s wetlands. The focus of this study is to evaluate the ecological service of China’s wetlands by compiling a dataset that include existing studies on China’s wetland valuation in both English and Chinese languages, which cover various valuation methods, and different types of wetlands. Based on the dataset, meta-regression method is used to model and analyze the influencing factors of the primary valuation results, and to build the parameters and transfer function for various ecological services. Finally, the benefit transfer method is applied to Yancheng wetland in Jiangsu.

This study may contribute to existing literature in following two aspects. First, it develops one of most comprehensive database on valuation studies on China’s wetland, which supplements Chinese literature on China’s wetland in existing literature. Second, it conducts meta-regression and benefit transfer to evaluate the specific individual ecosystem services of wetlands, to provide more detailed and meaningful information for both decision makers and researchers.

The rest of this paper is organized as follows. Section 2 describes the research methods, classification of wetland ecosystem services and valuation methods, and the databases. Section 3 presents the descriptive statistics, meta-regression models, and results. Section 4 conducts benefit transfer, analyzes errors, and applies benefit transfer to the valuation of Yancheng wetland. Section 5 is the conclusion.