Citizens may boost primary biodiversity knowledge - insights from the Danish fungal Atlas

Abstract

The Danish Fungal Atlas ran from 2009-13 and contributed with almost 250.000 records of fruit-body forming Basidiomycota (macrofungi) mainly submitted by volunteer citizen scientists. The data has been utilized in several research and conservation projects, but here we explore how the project contributed to the primary understanding of fungal biodiversity in Denmark. During the project, 197 species were recorded as new to Denmark, extending the national species list considerably. At least 15 of these appeared to be new to science. An even higher number of species previously recorded in Denmark, were however not reported in the project period, indicating a potential significant species turnover. Species with a mainly northern distribution were significantly overrepresented among the new Danish species, in marked contrast to climate change predictions. Species groups with inconspicuous or subterranean fruit-bodies were overrepresented both among the new Danish species and those only recorded before the project period. The same was the case for recently described taxa. Hence, we identified the species turnover to reflect factors relating to recording rather than actual biological changes in Danish nature. More specifically, improved taxonomic knowledge combined with an intensive sampling effort by citizen scientists guided by professional mycologists was concluded to be the main drivers of novel biodiversity discoveries in the project. Summarizing over the last 100 years an exponential increase in known macrofungal diversity in Denmark is evident, suggesting that even with the new knowledge generated in the project we are still far from a complete understanding of macrofungal diversity in Denmark. Denmark is one of the best studied countries for macrofungi globally, and at the same time one of the most heavily exploited, with nature under massive threat. Our research show that even under such conditions citizen scientists have potential to boost primary biodiversity knowledge.