Seasonal Changes in the Photosynthetic Activity of Terrestrial Lichens and Mosses in the Lichen Scots Pine Forest Habitat

Abstract

Photosynthetic activity is one of the most important metabolic processes that can be quickly and easily studied in the field. It can be used for identifying the environmental factors affecting ecosystem balance, as any stressor influencing metabolic and physiological processes will have a measurable effect on photosynthesis. The aim of this study was to measure the photosynthetic activity of selected lichens and mosses and investigate its changes resulted from diurnal and seasonal variability. We studied two lichens (Cladonia mitis Sandst and Cladonia uncialis (L.) Weber ex F.H. Wigg.) and two mosses (Pleurozium schreberi (Willd. ex Brid.) Mitt. and Dicranum scoparium (L.) Hedw.). Samples were collected in the area of lichen Scots pine forest of the “Bory Tucholskie” National Park. Our study revealed that the photosynthetic activity of cryptogams depended on species, season, time of the day, and water availability. Cladonia species, which are the main component of lichen Scots pine forests, have higher photosynthetic activity than Pleurozium schreberi, which represents species of fresh coniferous forests. Photosynthetic activity increased from spring through summer and reached the highest values in autumn. It was also higher in soaked samples collected in the morning and afternoon compared to noon. Despite the water access, noon samples still showed the lowest activity. This can result from natural changes in humidity during the day to which cryptogams are well-adapted.