Existence values are derived from environmental and other natural resource features which are appreciated by society (ie they place a value on them) irrespective of any other natural capital stock functions they may offer. Existence values are called 'non-use' values since they suggest that the natural capital stock has a value but that this is not associated with actual use. Such values instead reflect people's preferences, concern for, and sympathy with the resource (Turner et al 1994) and manifest themselves in imperatives of stewardship and good husbandry.

Whilst a very wide range of features can theoretically be assigned an existence value, it is more realistic to group elements of the natural capital stock when addressing existence value. In Hong Kong, it is likely that existence values can be placed on a number of environmental and natural resources, including the following groups of resources:

• natural and ecological resources: areas of countryside, nature reserves, SSSIs and marine parks and reserves along with particular habitats and species of renown including forests, mangroves, birds and mammals;

• environmental quality: water quality of rivers and streams, reservoirs and the marine environment (including beaches) as well as clean air, productive soil and land and a quiet environment. In this respect it is possible to envisage an existence value for assimilative capacity as a stock of resources which allows for future development and population growth;

• heritage resources: archaeological sites, historic monuments and other features of cultural, historical or architectural importance are often valued due to their spiritual, traditional/cultural and historical associations.