Zonal travel cost approaches to assess recreational wild mushroom picking value: Trade-offs between online and onsite data collection strategies

Mushroom picking is a growing recreational activity in Europe. Since the institutional environment moves towards regulating mycological resources, estimating the value of this ecosystem service becomes a key tool for policy-makers and rural entrepreneurs. This paper applies the Travel Cost (TC) method to estimate the value of mushroom picking in three forest areas in the region of Catalonia, Spain. In particular, the main objective is to contrast different sampling strategies (online vs. onsite data collection) when used to build zonal Travel Cost models. This intends to guide practitioners towards choosing the best sampling strategy according to existing time, monetary and accuracy constraints. Eight TC models were derived using as regressors the zonal travel cost and selected picking and socio-economic variables. The resulting demand curves produce an estimate of the average site value per trip that ranges from 9 to 22€/visit considering the onsite data, and from 21 to 47 €/visit for zonal TC implemented on the online data. These results reveal estimate differences across the approaches, and especially evident for one picking ground (Els Ports). Our results point out that onsite surveys would be better suited when exploring the sample for an initial set up of permit fees, to set the permit boundaries and initial applications. On the other hand, the online data collection presents the problem of self-selection and self-reporting bias. We recommend practitioners to always perform a proper assessment of the effects of the context, chosen sampling strategy, and validity of assumptions when adopting valuation estimates for establishing a recreational price of ecosystem services.