Variability of bryophytes and lichens on a forested coastal dune Tõotusemägi in Southwestern Estonia

Bryophytes and lichens are important in all dry land ecosystems due to their ability to colonize different substrates which are not suitable for vascular plants. They have an important role in vertebrates and invertebrate's food chain and function as a habitat for invertebrates. Nitrogen and carbon cycles in the forest depend greatly on the local bryophyte and lichen flora. The aim of present study was to investigate the frequency and variety of different species of bryophytes and lichens on the forested sand dune Tõotusemägi. The study was carried out on a 183 m long transect running on the western slope of the dune. Identification of bryophyte and lichen species was carried out and zonality of forest ground vegetation was demonstrated. Species were observed on the ground, on litter, on stumps and on trees. On the slope, 26 bryophyte species and 38 lichen species were registered. Dominating bryophyte species were Pleurozium schreberi (Brid.) Mitt., Hylocomium splendens (Hedw.) Schimp., Polytrichum juniperinum Hedw., Polytrichum piliferum Hedw, Dicranum polysetum Sw., Dicranum scoparium Hedw. Dominating lichen species were Cladina rangiferina (L.) Nyl., Cladina arbuscula (Wallr.) Hale & W. L. Culb., Cladonia furcata (Huds.) Schrad, Cetraria islandica (L.) Ach. Dominating species of epiphytic lichens were Hypogymnia physodes (l.) Nyl., Parmelia sulcata Taylor, Pseudevernia furfuracea (L.) Zopf, Parmeliopsis ambigua (Wulfen) Nyl. and Imshaugia aleurites (Ach.) S. L. F. Meyer. On the slope of the dune 12 different ground vegetation zones were distinguished. Bryophyte species characteristic for humid habitats and tolerant to shade were observed on foot of the dune. This may be caused by a stream flowing nearby which creates a more moist and nutrient rich habitat. The top area of the dune is open to direct UV radiation, therefore lichens and only some bryophyte species tolerant to dryness were observed.