Protected and Endangered Vascular Flora in the Forests of Plitvice Lakes National Park

Abstract

The study inventoried and analyzed the presence of 34 strictly protected and 11 threatened species of vascular flora within the forest vegetation of Plitvice Lakes National Park. The inventory was conducted on the basis of previously relevant findings and the authors’ own field observations across 323 complete or partial 1 × 1 km grid squares. Species occurrences within the grid squares were classified into five categories, ranging from very rare distribution (≤ 10 grid squares, Category I) to wide ranges extending over more than 60 % of the Park’s area (≥ 201 grid squares, Category V). It was found that 14 species have a very limited distribution, occurring on less than 3% of the total forest area (≤ 10 grid squares). A further 11 species were recorded in 11–50 grid squares (covering less than 17% of the area), whereas the remaining 20 species showed considerably higher frequencies and broader distributions within the Park’s forest ecosystems. The categories of very rare and rare species include taxa with narrow ecological valence (habitat specialists). They inhabit specific, sensitive, and spatially restricted habitats such as wet and flood-prone areas, more open limestone slopes and hillsides, ecotones, and non-forest areas. Since this group also includes species whose abundance decreases along the transition from non-forest habitats to closed and shaded forest stands, they are certainly present in the surrounding successional and open habitats as well. The category of rarely distributed taxa includes several typical forest species, primarily orchids (Cypripedium calceolus, Corallorhiza trifida, Epipactis sp.), as well as Ilex aquifolium and Taxus baccata. Based on the available data, their current distribution is considered stable, although it is assumed that yew and holly historically occupied a wider range that has been reduced over time due to long-term anthropogenic influence. Alongside these rare taxa, a substantial share of the Park’s flora is composed of widely distributed forest species that provide it with a distinctive natural identity. The analysis of the distribution and threat status of the inventoried taxa indicates that they currently occupy stable ranges within Plitvice Lakes National Park. The maintenance of this condition is expected, as no interventions are carried out in the Park that would lead to fragmentation, degradation, or alteration of forest habitats. Nevertheless, long-term threats, particularly for habitat specialists, include potential changes in the hydrological regime, progressive succession on non-forest areas, and the cumulative effects of climate change. Therefore, it is necessary to establish systematic monitoring of sensitive species on permanent plots and to implement targeted conservation measures. The results provide a relevant professional basis for improving management strategies and ensuring the long-term protection of the Park’s biodiversity.