METHODS Critical natural capital: a socio-cultural perspective Anna Chiesura *, Rudolf de Groot Environmental Systems Analysis Group, Department of Environmental Sciences, Wageningen University, PO Box 8080, 6700 DD Wageningen, The Netherlands Received 22 January 2001; received in revised form 22 July 2002; accepted 17 September 2002 Abstract Critical natural capital (CNC) is commonly defined as that part of the natural environment, which performs important and irreplaceable functions. So far, the challenge to determine the criticality of natural capital (NC) has mainly been taken up by the natural sciences, and the critical functions of nature mainly associated with its life-support and ecological services. Little attention has been paid to the socio-cultural functions of NC and to their values for the health and well being of human societies. The aim of this paper is to encourage a more complete accounting of the critical functions of NC and its associated values, by highlighting the importance of the information functions (health, recreation, amenity, education, heritage, etc.) for the quality and sustainability of human life. It is argued that, despite their immaterial and often intangible nature, these functions provide many, socio  /economic benefits, which might be assessed through both qualitative and quantitative valuation methodologies. Integration of ecology, sociology and economics is essential to operationalize the concept of CNC as a tool for more balanced environmental planning and decision making. # 2002 Published by Elsevier Science B.V. Keywords: Critical natural capital; Ecosystem functions; Environmental valuation; Information functions; Social and cultural values 1. Introduction The concepts of critical natural capital (CNC) and strong sustainability have been the object of academic debate for many years (Seralgeldin and Steer, 1994; Beckermann, 1995; Jacobs, 1995; Faucheux et al., 1997; Ayres et al., 2001). Grounded in neo-classical economic assumptions of capital theory, the original distinction between weak and strong sustainability has been taken up by other disciplines (i.e. environmental and ecolo- gical economics) and stretched into a spectrum of overlapping sustainability positions, ranging from a techno-centric ‘very weak sustainability’ to an eco-centric ‘very strong sustainability’ position (Turner, 1993). A central issue in the debate is the question to what extent natural capital (NC) is seen as critical to human society. Current ap- proaches to CNC refer to nature’s ecological or economic functions and values. However, natural ecosystems provide many functions and values that are not directly ascribable to the ecological or the economic domain, but which are nonetheless * Corresponding author. E-mail address: anna.chiesura@algemeen.cmkw.wau.nl (A. Chiesura). Ecological Economics 44 (2003) 219  /231 www.elsevier.com/locate/ecolecon 0921-8009/03/$ - see front matter # 2002 Published by Elsevier Science B.V. doi:10.1016/S0921-8009(02)00275-6