Which 'public'? Sampling effects in public participation GIS (PPGIS) and volunteered geographic information (VGI) systems for public lands management

Web 2.0 technologies including Public Participation Geographic Information Systems (PPGIS) and Volunteered Geographic Information (VGI) provide methods for engaging multiple publics in public lands management. We examined the effects of sampling in a PPGIS/VGI application for national forest planning in the US. A random sample (RS) of households and a volunteer public (VP) were invited to participate in an internet-based PPGIS to identify national forest values and use preferences. Spatial and non-spatial group responses were analysed. The VP group expressed stronger utilitarian values and consumptive use preferences while the RS group preferred forest amenities. These results would lead to different planning decisions. PPGIS/VGI methods should include scientific sampling to ground-truth voluntary participation.