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This paper addresses the lack of empirical evaluation of the use of web based surveys in the context of contingent valuation surveys. We compare, using a case study, in-person interviews with web based surveys regarding response rate, information additivity effects and respondents' attitudes towards paying. The web based survey had a much lower response (5.1%) than the in-person interviewing (84%). We find the web based contingent valuation surveys to be neither more susceptible to information additivity effects nor more prone to zero protest responses. We conclude in favor of the use of web based surveys, IntroductionThe contingent valuation method (CVM) is a stated preference method 1 for valuing changes in the provision of nonmarketable goods (e.g. environmental amenities). The method was conceptually proposed by CiriacyWantrup in 1947, but the first empirical application only took place in 1961 with Robert Davis, in the US (Jackobsson and Dragun, 1996; Venkatachalam, 2004). The contingent valuation method rose to high prominence in the 1980s and in the last two decades has been routinely used in the appraisal of projects with impact on the environment. Its potential to capture both use and non-use values of environmental assets and the flexibility of its application largely contributed to its massive use (Carson, 2000).Basically, CVM is a survey-based methodology which relies on obtaining monetary estimates for the economic value of a specified change in the provision of the environmental good of interest, which typically is not traded in the conventional markets. Hence CVM application consists in the construction of hypothetical markets (also called elicitation scenarios) where the individuals' valuation of the good is elicited. Monetary estimates are obtained either as individuals' Willingness to Pay (WTP) or Willingness to Accept (WTA). WTP measures the amount of income a person is willing to forego in exchange for an improved state of an environmental good. E-mail address: cristina.marta@ist.utl.pt (C. Marta-Pedroso). 1 Stated preference, or direct, methods employ constructed markets in an experimental setting to elicit individuals' preferences. Other stated preference valuation approaches include contingent ranking, contingent choice and conjoint analysis (see Boxall et al., 1996, for a comprehensive comparison of the various stated preference approaches).

We assessed the effects of landscape change on the climate regulation ecosystem service in a mountain river basin of Portugal, through the quantification, valuation and mapping of carbon sequestration and storage. The analyses were based on land use and land cover (LULC) changes that took place between 1990 and 2006 and on expected changes defined by three LULC change scenarios for 2020. We used the Integrated Valuation of Ecosystem Services and Tradeoffs model for scenario building and carbon assessment and valuation, and several modelling tools to assess past, current and future carbon in four different pools. Soil organic carbon data was obtained through an extensive sampling scheme across the entire study area. Recent (1990Recent ( -2006 and expected landscape changes (2006-2020) affected considerably carbon sequestration and storage. Observed landscape changes generally promoted carbon sequestration and storage, and had a positive effect on the climate regulation ecosystem service, both biophysically and economically. Expected LULC changes further extend the capability of the landscape to increase carbon sequestration and storage in the near future. The carbon sequestered and stored in vegetation and soil contributes to avoid socio-economic damages from climate change, while increasing the economic value of particular LULC classes and the whole landscape. These results are essential to inform land planning, especially on how, where and when changes in landscapes may affect the provision of the climate regulation ecosystem service. ARTICLE HISTORY

Halting the degradation and restoring the full capacity of ecosystems to deliver ecosystem services is currently a major political commitment in Europe. Although still a debated topic, Europe's on-going farmland abandonment is seen as an opportunity to launch a new conservation and economic vision, through the restoration of natural processes via rewilding as a land management option. Despite the ecological interest of restoring a wilder Europe, there is a need to develop evidencebased arguments and explore the broad-range impacts of rewilding. In this chapter