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Current and historical occurrence as well as coenotic affinity and ecology of Carex secalina in the Czech Republic and Slovakia are presented. The study is based on revision of herbarium specimens from 25 herbaria, literature data excerption and a field survey carried out during 2004-2010. Altogether, 168 sites were documented in the Czech Republic divided to two separate areas. Stabile occurrence trend was found in last decades, because 45 localities were documented in period 1975-1999 (27% of sites) and recent occurrence was confirmed at 42 localities (24% of sites). On the basis of our current knowledge the species was included into the IUCN threat category VU (vulnerable). In Slovakia, 19 localities of the species were recorded in total, but only 4 sites were confirmed recently (21% of sites recorded). However, only a small number of individuals was recorded there (less than 50 individuals in total) and half of this sites is acutely threatened by destruction (ploughing, secondary succession). Therefore, the C. secalina status in the Slovak Red List was changed to the IUCN category “critically endangered” (CR). Results of the study are summarised in the maps of historical and current species distribution. C. secalina usually occurred in halophytic grassland communities, especially in association Agrostio stoloniferae-Juncetum ranarii Vicherek 1962. However, it may occur in many other communities which suggest that the species had not well-defined coenotic relationships. On the basis of our knowledge, we consider C. secalina as an obligate halophyte.
A rare and protected species of the sedge Carex secalina was recorded in Dulsk near Inowrocław (Kujawy-Pomerania Province) in June 2014. It occupied the shores of ephemeral midfield water reservoirs in the complex of intensively used crop fields. Two subpopulations of this sedge with 36 tussocks in total were found. In the first subpopulation, the tussock diameter reached up to 25 cm, with 12–16 generative shoots per a tussock, while in the second subpopulation, the diameter was up to 10.5 cm, with 2–11 generative shoots. The rapid spread of this halophyte species is probably connected with the presence of permanent soil seed bank. This observation indicates a high potential of Carex secalina to colonise new habitats.
Carex secalina, a species recognized as extinct in Poland for 40 years, was re-discovered in 2000 and it’s natural populations covered by monitoring. From among nine historic localities, only for two - Jacewo and Turzany, in the vicinity of Inowrocław - the occurrence of the species was confirmed. In the course of the field studies, six new localities, not previously recorded in literature, were discovered. The sedge occupies sub-halophytic habitats in which it occurs along with halophytic species (particularly, such as Glaux maritima and Pucinellia distans) and a group of ruderal taxons. One of the newly discovered localities of C. secalina comprises an anthropogenic habitat. On the whole, the population sizes ranged from 20 to 350 individuals. The studies revealed a positive correlation between the size of a population and cattle pasturing, i.e. C. secalina forms the largest populations in the habitats remaining under the intense pressure of grazing and treading. Moreover, it was found that the high generative reproduction rate compensates the damage caused by animal grazing. The results suggest that an active protection of the sedge populations through the agricultural use of its habitats is the only effective way of securing it’s further occurrence in Poland, while including the sub-halophytic pastures with C. secalina in the agricultural and environmental program should be a priority task in the nearest future.
The size and reproduction ability of the three field populations of Carex secalina Willd. ex Wahlenb. have been assessed. In the parallel garden study selected traits from the life history of the species have been studied, such as age at first reproduction, fertility, the size of seeds, their germination ability and size of seedlings. The populations of C. secalina discovered in Poland in 2000 are characterised by small abundance and small area. All individuals from the three populations in the garden produced generative shoots in the third year of life. Statistically significant differences between the populations were found in the production of shoots with unisexual spikes and bisexual ones, the latter had not been reported in the hitherto literature on the species. The seeds started germinating after a 6-months rest. The first seedlings were observed in the first decade of May. The largest seedlings were noted in the population producing the smallest seeds. The results contribute to explaining the renewal of the populations of this species in the field.
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