The monetary valuation of ecosystem services has proved to be a powerful tool for influencing management decisions, as it can be used to quantify the relative importance of various ecosystem functions. However, these valuation methods are rarely implemented with adequate care; in particular, they do not consider spatial and temporal variations in the services offered and demanded. This paper examines the effect of heterogeneity on the valuation of cultural services offered by the Doñana natural protected area in Spain. We apply the zonal travel cost method at various spatial scales, and the individual travel cost method at various temporal scales. We conclude that economic valuation techniques must account for spatial and temporal heterogeneity if they are to provide accurate and realistic information.