In the context of voluntary geographic information (VGI), volunteers are not involved in the decision-making process. In addition, VGI systems do not offer powerful tools for conducting temporal analyzes. In this article, we propose to use the decision-making information systems to analyze VGI data, and we propose the definition of a new data warehouse design methodology, which allows the involvement of volunteers in the definition of analytical needs on VGI data. Our proposals have been tested on a real case study about biodiversity.