This paper offers a comparative evaluation of the scientific impact of a citizen science program in ecology, ''Vigie-Nature", managed by the French National Museum of Natural History. Vigie-Nature consists of a national network of amateur observatories dedicated to a participative study of biodiversity in France that has been running for the last twenty years. We collected 123 articles published by Vigie-Nature in international peer-reviewed journals between 2007 and 2019, and computed the yearly amount of citations of these articles between 0-12 years post-publication. We then compared this body of citations with the number of yearly citations relative to the ensemble of the articles published in ecology and indexed in the ''Web of Science" data-base. Using a longitudinal data analysis, we could observe that the yearly number of citations of the Vigie-Nature articles is significantly higher than that of the other publications in the same domain. Furthermore, this excess of citations tends to steadily grow over time: Vigie-Nature publications are about 1.5 times more cited 3 years after publication, and 3 times more cited 11 years post-publication. These results suggest that large-scale biodiversity citizen science projects are susceptible to reach a high epistemic impact, when managed in specific ways which need to be clarified through further investigations.