The most prominent threats to epiphytic lichen funga are modern industrial forestry and air pollution. Macrolichens with cyanobacteria, cyanolichens, are particularly vulnerable. One of these is the lungwort lichen, Lobaria pulmonaria. The lungwort lichen is not among the most threatened species in Sweden, but the populations have nevertheless decreased significantly during the last 100 years. One area where the lungwort lichen still can be found is around lake Möckeln, in the south of Sweden. In earlier inventories 94 trees with Lobaria pulmonaria were identified. The aim of this study was to investigate the population changes of L. pulmonaria in this area as well as the ecology and management options for this species. My questions were: 1. Does the population of L. pulmonaria around the lake Möckeln decrease?  2. Is there a positive correlation between the circumference of the trees and the coverage of lichens? 3: Is there a positive correlation between the number of individuals and coverage? 4: Is there a positive correlation between the circumference of the trees and the number of thalli?  5: Is there a negative correlation between the size of the populations and the proximity to the lake? Between 2001 and 2024 the total population decrease was 23%. There was no correlation between circumference and coverage or number of individuals. No effect of nearby water bodies on population size could be detected. There was, however,  a strong correlation between coverage and the number of thalli. This result is not obvious since thalli can vary substantially in size. The results which suggest a decline are consistent with earlier studies in southern Sweden which also show a decrease of the L. pulmonaria populations in the south of Sweden. Since L. pulmonaria forests have high conservation values I propose that all the sites investigated in this study should receive protection as nature preserves.