A systematic literature review of non-market valuation of Indigenous peoples' values: Current knowledge, best-practice and framing questions for future research

Non-market valuation (NMV) can be effective to understand the value people place on ecosystem goods and services for which there are no market prices. Over the last 20 years, NMV has increasingly been applied to Indigenous contexts, albeit with important conceptual and methodological limitations. We conduct a global systematic literature review and detailed meta-synthesis of 63 peer-reviewed studies on NMV research applied to Indigenous peoples' values. Selected studies are categorized by methods, year of publication, geographic area and ecosystem components. Australia (n = 19), the USA (n = 9) and Canada (n = 8) account for over half of all articles. Important knowledge gaps remain in the NMV peer-reviewed literature for other geographic areas. Our taxonomy based on 'whose values' and 'which values' reveals that a large proportion of studies (n = 24) focused on values held by Indigenous peoples, predominately on direct-use values (n = 12) and total economic values (n = 10). Studies based on the general population (n = 17) typically examined altruistic and/or existence values (n = 15). Our analysis identified seven main strategies used by previous studies to overcome critical limitations of NMV when applied to Indigenous peoples' values. Strategies include: (1) engaging directly and ethically with Indigenous peoples; (2) investigating multi-dimensional values; (3) valuing health benefits; (4) adopting non monetary payment vehicles; (5) using market prices for valuation; (6) sampling the broad population; and (7) investigating non-cumulative values. Based on this review, we provide seven critical questions to guide future NMV research: (1) What is the purpose?; (2) How does Indigenous knowledge inform NMV?; (3) Who benefits?, (4) What ethical frameworks apply?; (5) Whose values are considered?; (6) What is the expected change?; and (7) How are NMV limitations handled? Our contribution provides researchers and policy-makers with the most upto-date review of the state-of-knowledge and suggestions for best-practice on the use of NMV methods when applied to Indigenous peoples' values.