Problems and challenges of lichen inventory in a changing environment: The case of the “Mszar” and “Redykajny” reserves in Olsztyn

The paper presents the state of knowledge of the lichen biota of the “Mszar” and “Redykajny” nature reserves, located in the “Las Miejski” urban forest complex in Olsztyn (north-eastern Poland). The results of the inventory conducted in 2024 are described, which are compared with published data collected in 1999–2001. So far, a total of 118 lichenized and three non-lichenized fungi have been identified in this area. Recent studies did not confirm the occurrence of 18 species, but at the same time showed 32 species new to the study area. The article discusses possible causes of changes in the species composition of the lichen biota over almost 25 years and the effectiveness of various methods of collecting data in the field. The results prove that both reserves are still important refuges of forest lichen biodiversity on a scale larger than just the area of Olsztyn’s urban forests.