Radomír Řepka

Comparison of the floodplain forest floristic composition of two riparian corridors: species richness, alien species and the effect of water regime changes

Abstract Floodplain forests are sensitive to changes within the surrounding environment and contain the most highly invaded habitats. The overall aim of this study was to characterise floristic composition of floodplain forest along two different riparian corridors. The studied river ecosystems were influenced by human disturbances, but they have historically different hydrological management practices (e.g., damming and water regime management). We hypothesised that different hydrological management practices affect the composition and diversity of vegetation and influence multiple ecosystem functions and services in floodplain forests. A detailed study of the vascular plant species diversity of floodplain forests in the lower parts of two riparian corridors of the Thaya and Morava Rivers (South Moravia) was conducted. Altogether, 853 species of vascular plants were recorded, including 121 species of woody plants. We found 111 species that are protected by law or threatened according to the Czech Red List. We found 230 alien species, out of which 125 are archaeophytes and 105 are neophytes. Thirty-nine species are invasive; however, the most frequent group comprises naturalised archaeophytes (78). Differences in the effects of environmental factors on species richness and the proportions of alien and endangered species were tested using generalised linear models (GLMs). Differences in species composition in the two distinct riparian corridors were examined using non-metric multidimensional scaling (NMDS). Although only small differences were observed in the vegetation composition, we observed some differences in species richness and species composition between the riparian corridors. The most obvious difference was a higher proportion of alien species in the Morava River corridor than in the Thaya River corridor. In contrast, the proportion of endangered species richness was higher in the Thaya River corridor. We assume that the most probable explanation of the differences is the unique water management history for each river corridor.

Comparison of vascular plant diversity and species composition of coppice and high beech forest in the Banat region, Romania

Abandonment of coppicing is one of the main reasons of diversity decline in European temperate forests. To reverse this trend, coppicing has been reintroduced in several forests, especially in areas of high conservation value. However, empirical information on the effects of coppicing on plant diversity and composition is still scarce. By comparing vegetation data from active coppices and beech-dominated high forests in the Banat region in Romania, we tested the hypothesis that coppices have a higher plant diversity and different plant species composition than high forests. Data were collected in 60 randomly placed phytosociological relevés and were analysed using linear models and multivariate methods. As expected, we found differences in understorey plant composition. Herb species with various environmental demands–sciophytes-(hemi)-heliophytes and grassland species–were more frequent in coppices whereas high forests had more vernal species and sciophytes. Coppices also had slightly greater plant diversity but did not differ in herb species richness. Our results demonstrate that coppicing has a small positive effect on plant diversity but a large effect on species composition. Coppice restoration may be especially beneficial for populations of thermophilous and non-forest species.

Vascular plant biodiversity of floodplain forest geobiocoenosis in Lower Morava river Basin (forest district Tvrdonice), Czech Republic

ABSTRACT This paper presents an evaluation of full-area floristic mapping of floodplain forest in Tvrdonice forest district (Židlochovice Forest Enterprise) based on a single forest stand inventory. The study area encompasses 2,200 ha of forests, where 769 segments were inventoried, and 46,886 single records about presence of vascular plant species were catalogued. We found 612 species (incl. subspecies and hybrids), out of which 514 were herbs, 98 were woody plants, 113 were endangered species and 170 were adventive species. The average area of a segment is 2.86 ha. The mean number of species per segment is 60.97 in a range of 4-151.

Habitat requirements of endangered species in a former coppice of high conservation value

Transformation of coppices to high forests has caused fundamental changes in site conditions and a decline of many species across Central Europe. Nevertheless, some formerly coppiced forests still harbour a number of the declining species and have become biodiversity hotspots in the changing landscape. We focused on the best-preserved remnant of formerly grazed and coppiced subcontinental oak forest in the Czech Republic – the Dúbrava forest near the town of Hodonín. To improve our understanding of the ecology of declining species, we studied local habitat requirements of vascular plants most endangered at the national level. We recorded vegetation composition and sampled important site variables in plots with the largest populations of endangered species and in additional plots placed randomly across all major forest habitats. We demonstrated that sites with endangered species have a highly uneven distribution in ecological space and that their species composition is often similar to open-canopy oak forests. Within this habitat, the endangered species are concentrated in places with a high light availability and high soil pH. Light-demanding species characteristic of subcontinental oak forests are the best indicators of these sites, while broadly distributed shade-tolerant and nutrient-demanding species avoid them. These results support the view that the occurrence of many endangered species in the Dúbrava forest is a legacy of the long history of traditional management that kept the canopies open. Light-demanding species are now threatened by ongoing successional changes. Therefore, active conservation measures are recommended, including opening up the canopies, early thinning of young stands, control of expansive and invasive species and understorey grazing or mowing.

Carex socotrana, a New Endemic Species from Socotra Island

ABSTRACT. We describe Carex socotrana Rěpka & Maděra, a new endemic species found in the Hajhir Mountains on Socotra Island. It differs from the morphologically similar African continental species C. steudneri Boeckeler in having a shorter stem, smaller leaf length and width, completely smooth leaf blades and margins, and pistillate scales without a whitish membranous margin and with distinctive awns at the apex. The spike clusters are smaller and more scattered on the stem, and the perigynium and its beak are smaller than in C. steudneri. So far only one small and one large population have been found near the highest mountain peak, Mount Scand. The new taxon is 1370 km from the closest known site of C. steudneri.

Tree shape and form in ancient coppice woodlands

Abstract Ancient coppice woodlands are coppice-originated forest stands with a long-term continual development, and with the preserved typical natural and historic elements of old sprout forests. Prominent natural elements in the ancient coppice woodlands are namely old coppice stools. There is, in scientific literature, lack of information about features of ancient coppice stools. Therefore, our contribution aims to describe shape and form of ancient coppice stools, including the most important microhabitat of coppice woodlands – dendrothelms. Based on field survey of 20 localities of important coppice woodlands we recorded 135 ancient coppice stools of 13 tree species and a total of 80 dendrothelms in 9 tree species. Basic features of ancient coppice stools and dendrothlems were measured and evaluated.

A New Subspecies and a New Combination in Gymnocalycium sutterianum (Cactaceae, Trichocereeae) from Argentina

Abstract. The new subspecies Gymnocalycium sutterianum (Schick) Hosseus subsp. arachnispinum Řepka (Cactaceae, Trichocereeae) is described from Córdoba, Argentina. It differs from the nominate subspecies mainly in the following morphological characters: a smaller plant body, shorter distances between areoles, smaller hemispherical tubercles (8–12 mm in diameter), seven to nine shorter spines (7–10 mm) per areole that are shorter and often bent over the tubercles, thinner spines in cross-section 0.25–0.4 mm in diameter, smaller flowers, and pericarp to perigon ratios from 1:2 to 2:3. The new subspecies also differs in genome size and ploidy level (G. sutterianum subsp. sutterianum 2n = 6x, G. sutterianum subsp. arachnispinum 2n = 4x). Moreover, populations of the new subspecies are found in a separate distribution area from that of the nominate subspecies. The new combination G. sutterianum subsp. dolezalii (Halda & Milt) Řepka [≡ G. poeschlii Neuhuber subsp. dolezalii Halda & Milt] is established and the subspecies name is neotypified. A taxonomic key to identify the three subspecies of G. sutterianum is included.

Gymnocalycium campestre (Cactaceae, Trichocereeae), a New Species from Córdoba, Argentina

Abstract. The new species Gymnocalycium campestre Řepka is validated from Córdoba, Argentina, and is affiliated with the G. erinaceum J. G. Lamb. group of Gymnocalycium Pfeiff. ex Mittler subg. Gymnocalycium (Cactaceae, Trichocereeae). The new taxon is compared with several sympatric close relatives or similar taxa. Distinctive characters of the new species include the gray-green plant body with frequently bronze-colored epidermis, distinct tubercles under the areola, the radially arranged, whitish (often chalky) marginal spines (mostly seven) with the longer portion of the spine with colored base, further considerably long and whitish to pale pinkish or pinkish colored flowers, with perianth often 1 to 1.5 times longer than the pericarpel. Flowering time is intermediate in relation to that of other taxa of the group (end of spring, December in Argentina). The seeds are small (1.197 ± 0.048 mm long) within the group. The new species significantly differs in genome size and ploidy level (tetraploid) from other taxa of the G. erinaceum group (diploids). The new taxon has been found in 27 populations, which documents a distributional area separate from that of other related taxa, with the exception of G. erinaceum. Based on the morphological, cytological, and geographical features, the authors hypothesize that the new species may have a hybridogenous origin, formed by hybridization and introgression from ancestors that occur in its geographic vicinity.