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Floristic peculiarities of the Natura 2000 site Mačkovec Fishponds (Northern Croatia)

NATURA 2000 site Mačkovec Fishponds (HR2001034) is one of the seven Special Areas of Conservations (SACs) in Međimurje County (Northern Croatia). The site encompasses three artificial retentions, with total area of 3 ha, subject to significant changes in water level. The site is designated as important for the preservation of amphibian habitats of the Littorelletea uniflorae and Isoeto-Nanojuncetea vegetation, according to the Habitats Directive. Characteristic plants of these vegetation types are generally small ephemerophytes, forming short annual or perennial vegetation. This pioneer vegetation is characteristic for land and water interface zones of lakes, pools and ponds, and develops on nutrient-poor soil during periodic drying of these standing waters. The botanical inventory of this site, conducted during the summer of 2022, revealed several floristic peculiarities. Dominant plant species forming annual vegetation of dried pond floor were Filaginella uliginosa (L.) Opiz), Cyperus michelianus (L.) Link and Eleocharis ovata (Roth) Roem. et Schult. The latter is an endangered (EN) species with sparse distribution across Croatia. Among the vascular plants, a large population of ephemeral thalloid liverwort Riccia cavernosa Hoffm. was covering the bare cracked soil and the vertical faces of soil fissures. This rare short-lived bryophyte is associated with moist and fine textured substrata of the lacustrine drawdown zones. It was only recently confirmed for Croatian byroflora. Along the margins of the retentions, minute vascular plants Lythrum portula (L.) D. A. Webb and Callitriche palustris L. were registered, along with the ephemeral moss Physcomitrium sphaericum (C. F. Ludw. ex Schkur.) Brid., for which this is the second known site in Croatia. Rare data deficient (DD) Elatine hexandra (Lapierre) DC., found on this site in 2006, was not confirmed. Although the vascular and bryophyte species of Littorelletea uniflorae and Isoeto-Nanojuncetea are considered relatively rare and threatened in Europe, the low number of records in Croatia is to a considerable extent the result of insufficient research into ephemeral habitats and their flora in general.

Eleocharis ovata, ephemeophytes, Isoeto-Nanojuncetea, Physcomitrium sphaericum, Riccia cavernosa

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