Basic characteristics of the flora and vegetation
A) The vegetation of the plateau
a) Natural vegetation
The potential vegetation on a large part of the plateau are oak-hornbeam forests, especially Hercynian oak-hornbeam stands of the Melampyro nemorosi – Carpinetum association. These have been preserved on a considerable proportion of their original area, but in places they have been replaced by cultural forest stands with a predominance of pine and larch as well as false acacia stands in the eastern part of the park. Small areas on the plateau are covered with the notable association of oakwoods with Cinquefoils – Potentillo albae – Quercetum on heavier soils. No remnants of the natural forest vegetation have survived on the hills in the south-eastern part of the territory, but in addition to the sub-Pannonian oak-hornbeam stands Primulo veris – Carpinetum, we can assume that the southern slopes of the hills were previously covered with thermophilous oakwoods (e.g. oakwoods with Wild Service Trees – Sorbo torminalis – Quercetum). The plateau above the right bank of the Dyje in the western part of the territory (Vranov area) would have had beechwoods with melic grasses Melico-Fagetum) but only small areas of this woodland type have survived here. These complexes of mesophilous and xerophilous forest types are only interrupted in the shallow valleys of streams by areas of alluvial forest, and the rare localities with stagnant water are covered with alder carrs with Gingerbread Sedge (Carex elongata), which have been best preserved in the section between Lesná and Čížov. In these valley forests we can find Remote Sedge (Carex remota), Marsh Cranesbill (Geranium palustre), Senecio rivularis of the Aster family, Marsh Hawksbeard (Crepis paludosa) and Purple Moor-grass (Molinia caerulea).
b) Replacement vegetation
On a part of the plateau in the NP the forests have been removed and the land transformed into arable lands, meadows and extensive pasturelands. In the south-eastern part of the territory the pastures are of a semi-natural character. The effects of burning and extensive grazing have given these areas the form of closed heathlands forming a mosaic with areas of dry grasslands. In some places the shrub communities are dominated by Heather (Calluna vulgaris) and Hairy Greenweed (Genista pilosa). Less frequent shrubs are the Regensburg Broom Chamaecytisus ratisbonensis and the Dwarf Broom Cytisus procumbens. Of the less common shrubs which grow here we can also mention the Burnet Rose (Rosa pimpinellifolia) and European Dwarf Cherry (Prunus fruticosa). Notable herbs and grasses which grow on these pastures and heaths include the Dwarf Sedge (Carex humilis), the Great Feather-grass (Stipa pennata), the Saxifrage Saxifraga bulbifera and the eye-catching Purple Mullein (Verbascum phoenicium) etc. In the spring we can see the flowering Great Pasque Flower (Pulsatilla grandis), Early Star of Bethlehem (Gagea bohemica), the Dillenius’ Speedwell Veronica dilenii, as well as the orchids – Green-winged Orchid (Orchis morio) and Elder-flowered Orchid (Dactylorhiza sambucina). Notable summer-flowering species include the Dwarf Everlasting (Helichrysum arenarium), the Thrift Armenia vulgaris and on the loess cover we can find the Goldilocks Aster (Aster linosyris) and the Italian Aster (Aster amelbus). Xerothermophyte plant communities can also be found on the rocky outcrops which were prepared by erosion, on loess cover and on the shallow soils around the rocky outcrops. Meadow vegetation has been preserved in the deforested stream valleys in the south-western part of the territory, where the most significant plant species are the Sedge Carex caespitosa, the Creeping Willow Salix rosmarinifolia, Globe Flower (Trollius altissimus) and the Western Marsh Orchid (Dactylorhiza majalis). Several small ponds have of aquatic and litoral vegetation which has mostly developed fragmentally. In the pond “U Jejkala” we can find the aquatic macrophytes – Wavy Bladderwort (Utricularia australis) and Fine-leaved Water Dropwort (Oenanthe aquatica). Significant plant species can also be found in the anthropogenic vegetation in the agricultural landscape of the Podyjí NP buffer zone. Some of the weed communities on ruderal lands or wastelands are especially valuable and we can find species growing here which are now rare elsewhere (e.g. Summer Pheasant’s Eye Adonis aestivalis, Spurge Flax (Thymelaea passerina), Austrian Chamomile (Anthemis austriaca) etc).
B) Vegetation of the Dyje valley
a) Natural vegetation
The canyon-like valley of the Dyje has a very well-preserved natural vegetation. On the valley rim and the convex upper parts of the south-facing valley slopes we can find oakwoods (oakwoods with fescues – Festuca ovina – Quercus petraea and oakwoods with wild service trees – Sorbo torminalis – Quercetum). The tree layer is comprised predominantly of oaks, including the Sessile Oak (Quercus petraea), the oaks Q. daleschampii and Q. polycarpa. We can also find scattered Whitebeam (Sorbus aria), Wild Service Tree (S. torminalis) and Cornelian Cherry (Cornus mas). The shrub layer is poor and only includes Alder Buckthorn (Frangula alnus) and Juniper (Juniperus communis). The herb layer includes Wavy Hair-grass (Avenella flexuosa) and White Wood-rush (Luzula luzuloides). In open sections of the oakwoods such as at the Liščí skála rocks, the shrub communities also include the rare Garland Flower – Daphne cneorum, especially around Havraníky. In the most exposed places along the whole Dyje valley we can find rocky pinewoods of the Cardaminopsio petraeae-Pinetum or oakwoods with hairy greenweeds of the Genisto pilosae-Quercetum petraeae type e.g. on the Ostroh peninsula or above the Hamerské vrásy rock formation. Communities of rocky steppe with a relatively rich flora can be found on the steepest rocky slopes and cliffs. Plants which grow here include Cotoneaster (Cotoneaster integerrima), the Needle Grass (Stipa capillata), Great Pasque Flower (Pulsatilla grandis), the Moon Carrot Seseli osseum, Yellow Onion (Allium flavum), the Cinquefoil Potentilla arenaria and the relict species Golden Alyson (Aurinia saxatilis). These communities can be found fringing the river valley throughout the national park, for example at Pašerácká stezka, Hamerské vrásy at Ostroh, on the rocks below Nový Hrádek castle etc. On similar localities on the basement of crystalline limestone near Čížov we can find thermophilous oakwoods with wild cherries of the Corno-Quercetum and Pruno mahaleb-Quercetum pubescentis associations with exceptionally rich shrub and herb-grass layers. The tree layer is dominated by Pendunculate Oaks (Quercus robur) whereas Downy Oaks (Q. pubescens) are completely absent here (they only occur in the eastern part of Podyjí – Hnanice, Šobes, Havraníky). Eye-catching species which can be found on the slopes on alkaline rocks include Burning Bush (Dictamnus albus), Yellow Monkshood (Aconitum anthora), Swordleaf Inula (Inula ensifolia), Purple Gromwell (Lithospermum purpurocaeruleum) etc. We can also find orchids such as the Burnt Orchid (Orchis ustulata), Lady Orchid (O. purpurea) and Military Orchid (O. militaris) here, as well as the Greater and Lesser Butterfly Orchids (Platanthera chlorantha and P. bifolia). From the other species the presence of the Cross Gentian (Gentiana cruciata) is of note. On analogical localities which lie on north-facing slopes, where the conditions are cooler and damper, we can find poor acidophilous oakwoods of the Luzulo albidae – Quercetum petraeae association. On the concave lower parts of the slopes, which are colder due to the temperature inversion and have a deeper soil cover due to the accumulation of slope material, we can find oak-hornbeam woods with the typical grove herbs such as Bird-in-a-Bush (Corydalis solida), Hepatica (Hepatica nobilis) and Cowslip (Primula veris). In shaded areas the herb layer includes Cyclamen purpurascens, Martagon Lily (Lilium martagon) and Mezereon (Daphne mezereum). Sub-montane beechwoods of the Tilio cordatae-Fagetum can be found on north-facing slopes in the north-western part of the territory (Braitava). Steep slopes under rock formations with accumulations of boulders are covered with talus forests – maple-hornbeam stands of the Aceri-Carpinetum association. Here we can find Nine-leaved Toothwort (Dentaria enneaphyllos), Baneberry (Actaea spicata) and Perennial Honesty (Lunaria rediviva). On the opposite bank of the Dyje river around Ledové sluje there is a notable relict occurrence of the Foetid Bugbane (Cimicifuga europaea) and an abundant population of the sub-Alpine Alpine Rose (Rosa pendulina). According to dendrological experts there is also a native population of Norway Spruce (Picea abies) in this area at an unusually low elevation above sea level. These spruces even reproduce by layering. On the slopes around Ledové sluje we can also find one of the last fragments of viable stands of Silver Fir (Abies alba) in the national park. Approximately 20 autochthonous individuals of Yew (Taxus baccata) grow in the slope beechwoods at Braitava. Wych Elms (Ulmus glabra) are still relatively numerous in talus localities. The rocky slopes of the Dyje valley are also typified by their primary forest-free enclaves, where certain orchids such as the Burnt Orchid (Orchis ustulata) and the Military Orchid (O. militaris) also grow. In addition to these rocky outcrops, the second type of primary forest-free areas in the Dyje river canyon are the granite and gneiss boulder fields of peri-glacial origin. On south-facing slopes these boulder fields are only covered with epilithic lichens, whereas on the damper north-facing boulder fields, especially those in close contact with the forests, we can find fern communities of low species diversity. The alluvial plain of the Dyje river is covered with alder stands (especially alder stands with chickweeds – Stellario-Alnetum glutinosae) and the river flow is fringed with riverine reedbeds, although we can also find fragments of willow scrub in places. In many parts of the Dyje riverbed we can find growths of River Water Crowfoot (Batrachium fluitans).
b) Replacement vegetation
In the past a large proportion of the alluvial forest stands were converted into alluvial meadows (which were cut for hay) and have a very high species diversity. An example of a developed alluvial forest stand can be found at the mouth of the Klaperův potok stream, where we can find massive examples of White Elm (Ulmus laevis) and White Willow (Salix alba). The herb layer includes the Oxlip (Primula elatior), Snowdrop (Galanthus nivalis), Large Bittercress (Cardamine amara) etc. In several places by the Dyje river (Ledové sluje) and in the tributary stream valleys (Klaperův potok) we can currently find regenerating stands of waterlogged alder carrs, which are often taking over meadows which have been abandoned.