A new locality of Lycopodiella inundata (Lycopodiaceae) against a background of it occurrence in the Podlasie province (NE Poland).
Marsh clubmoss Lycopodiella inundata (L.) Holub has been recorded in the Podlasie province in 10 scattered localities except for the western part of the region. Recently, the existence of only three populations has been confirmed (in Pojezierze Wschodniosuwalskie, Wzgórza Sokólskie and Równina Bielska) and four populations have been recognized as extinct. A newfound population near the village of Czechy Orlańskie is quite small and occurs only at the extensively mown banks of the fire fighting reservoir. It consists of a maximum of 80 shoots growing on 30 m2 of early successional wet habitat with features of Nardus grasslands. In the stand and its vicinity expansive species (Rubus spp., Deschampsia caespitosa, Holcus lanatus) and juvenile trees (Betula pendula, Alnus glutinosa) including invasive species (Padus serotina) have been noticed. Lycopodiella inundata populations often have ephemeral status. Their existence depends on a few factors, among which the most important are: high groundwater level (with lack of the long-term flooding), full sunlight, meso- or oligotrophic conditions and weak interspecific competition. Main endangerments for marsh clubmoss populations and its habitats are caused by changing water conditions, eutrophication and increasing interspecific competition due to secondary succession. Effective protection of the species should be of a landscape or even regional scale. The active protection at local level also should be done, but it seems less important. What seems significant for Lycopodiella inundata populations is maintaining: numerous habitats of meso- and oligotrophic wetlands, extensively used wet Nardus grasslands and heathlands, and alternative anthropogenic habitats which can be colonized in easy way by the species.