Unveiling hidden diversity: charophytes in vanished and ephemeral ponds of the Special Nature Reserve “Deliblato Sands” pondscape (Serbia)

Abstract

The main aim of the present study was to describe and compare the charophyte diaspore bank content and apparent viability in six dried-up and three overgrown, but still ephemeral, ponds within the Special Nature Reserve “Deliblato Sands” pondscape (Vojvodina province, Serbia). The stated aim was formulated as a preliminary step towards evaluating the condition of the charophyte diaspore bank and its potential for successful restoration, provided suitable conditions are met. We tested the hypothesis that the apparent viability of diaspores preserved in the sediment of ephemeral ponds is significantly higher than in the sediment of dried-up ponds. At least six charophyte taxa were detected in the form of propagules (Chara braunii, Chara globularis, Chara vulgaris, Chara spp., Nitellopsis obtusa, Sphaerochara prolifera). Compared to “dried-up ponds”, the “ephemeral ponds” group showed significantly higher apparent viability of diaspores, along with greater overall abundance and species richness. Yet, with worsening aridity and the increasing ecological pressure exerted by drought-tolerant woody and/or invasive species, their future ability to maintain charophyte diversity is uncertain. Our results suggest that charophytes once had a much broader distribution in the investigated region, which has since been lost. The urgent need for habitat restoration and revitalization is highlighted.