The Countryside around Portz Insel
The countryside of today’s floodplain of the stream Včelínek (in German Niklasgraben) which begins a short distance south of Mikulov in Austria, has a rich and varied history.
In geological history there was a larger watercourse probably flowing here, equivalent in volume to the present-day river Dyje, which now flows northwards around the Pavlov Hills in the layers deposited in the Mesozoic and in particular Tertiary eras. Sedimentation soils with high salinity developed here and sulphur springs arose. That is why people built and operated ponds in this area from the Middle Ages onward
At present, Nový and Sedlecký ponds are in the vicinity, more distant is Šibeník pond, Horní and Dolní Mušlovský ponds are situated on the outskirts of Mikulov, and in the opposite direction the system of Lednice ponds extends, with the biggest Moravian pond named Nesyt. Diverse biotopes, more or less affected by water, gradually evolved here. The floodplain is favourable for mixed ash-alder floodplain woods, but the largest areas here are covered by wetland willows and reeds. Locally they are adjoined by fields and, near the summer house, by the newly planted vineyards.
The appearance of Portz Insel surroundings was greatly changed due to the development of the railway line (Břeclav – Znojmo) and the establishment of the “border zone”.
The territory of approx. one square kilometre represents a diverse range of different nature and landscape protection regimes. Nový pond and the adjacent willow and poplar woods north of the railway and Sedlecký pond, the land extending as far as Sedlec u Mikulova are part of the Pálava protected landscape area and are included in the 1st - 3rd protection zone, and they also belong to the Important Bird Area under Natura 2000, which is identical with the Protected Landscape Area (CHKO). With the part along the national border included, it also belongs to the Lower Morava Biosphere Reserve (UNESCO).
There are several small protected areas around Portz Insel. In the Pálava protected landscape area, the Šibeničník natural reserve (NR) rises south of Mikulov, also the Holy Hill NR in Mikulov is in sight, situated northwards is Liščí Hill and, near Sedlec u Mikulova, The nearby sandpit Mušlov (proposed natural monument) with its finds of Mesozoic mollusc shells and shark teeth, is also of great interest. Closest to the island, though already outside the Natural monument Skalky of the Pálava protected landscape area, is the Natural monument Skalky, extending along the national border, or the Natural monument Paví Hill, surrounded by the field.
It is the variety of natural conditions and diversity of landscape features that determines relative abundance of the protected plant and animal species. Attractive among plants is Dactylorhiza incarnata, the early marsh-orchid growing on the meadow among reedbeds. Predominantly represented are animals, in particular the groups and species depending on wetland or water environment. Inconspicuous are representatives of various insects, of which the flat bark beetle (Cucujus cinnaberinus) lives under the bark of dying poplars, protected under the Natura 2000 protected sites network.
Among amphibians, we regularly find here the green tree frog, both species of toad, several species of common frogs and the rare spadefoot toad. Wetlands and canals with water are home to grass snakes and in particular to the landscape “builder”, Eurasian beaver, who constructs dams and beaver ponds here. The traces of beaver teeth on trees are well visible everywhere. The western marsh-harrier is frequently seen flying out of and over the reedbeds, while the water rail, bearded tit and little bittern live in them. The hanging nests made by penduline tits are seen on trees around the pond, and on the water surface we will catch glimpses of greylag geese and various duck species, the most interesting of them being red-crested pochards or gadwalls, grey herons and great white egrets. Flute-like calls of golden orioles are heard from the tops of tall trees.
The Natural Reserve “Liščí vrch”
The reserve north of the village of Sedlec protects dry grasslands, fallow land and shrubs with many specially protected plant and animal species. One example is hairy flax which, through its ground covering summer flowering, lends the area sky-blue colouring. The reserve is part of the Mikulov Highlands.
The National Park “Slanisko” (Salt marsh) around Lake Nesyt
Our largest salt marsh (7 ha) lies in the vicinity of the village of Sedlec and the largest Moravian pond named Nesyt. The salty character of soil in the reserve is caused by the leaching of salt out of the bottom layers; sulphur springs also occur here. Plants, i.e. sea aster (Tripolium pannonicum), sea plantain or swamp prickle grass (Heleochloa schoenoides), adapted to such environment, are called “halophytes”.
The Natural Monument “Paví” Hill
Situated south of the village of Sedlec, surrounded by the field, the area is characterized by thermophilic steppe turf, where the greater pasque flower (Pulsatilla grandis) and pheasant's eye (Adonis vernalis) bloom in the spring. In the summer it is an important insects locality.
The Natural Monument Skalky near Sedlec
Features several abandoned earth pits (former limestone mines) where limestone was extracted from the blocks deposited in sands. The locality is recorded as a site of special geological interest for a rich occurrence of fossils from the Tertiary Baden seas.