Libický luh National Nature Reserve

Libický luh NNR was declared in 1985 on a territory of 410 ha, to protect the largest complex of lowland alluvial forest in the Bohemia with a range of natural forest communities which have developed in connection with the height of the groundwater table and the periodicity of flooding, the flowing water and stagnant pools at various stages of sedimentation from open water surfaces to marsh alder stands and the hygrophilous and mesic Labe floodplain meadows with high species diversity. The NNR is included in the proposed Libické luhy Site of Community Importance.

The territory is located in the Central Bohemian region, near to the municipality of Velký Osek and on the alluvial plain on the right bank of the Labe river. The reserve lies at elevations of around 190 metres above sea level. The geological substrate is of sands and gravels, which lie on cretaceous marlstones. The soils consist of fluvisols and sediments from the oxbow lakes of the Labe river. The Labe, which originally migrated across the basin has left behind numerous pools and oxbow lakes, including the Staré Labe (Old Labe channel) – a Labe meander which was cut off from the river during flow regulation work in the second half of the 19th century. The Bačovka stream also flows through the reserve. Libický luh NNR lies in a warm climatic zone.

The great majority of the territory is covered by hardwood alluvial forest stands, with oak-hornbeam stands in drier areas. Smaller areas of willow-poplar alluvial stands and marsh alder stands are also found here. In addition to the forest stands with a near-natural character with a richer species, age and spatial structure and a higher proportion of dying and dead trees, significant areas are also covered by single-species, same-age stands especially of pendunculate oak (Quercus robur). In many parts of the reserve we can also find trees which are not natural for the geographical region or the local conditions, including false acacia (Robinia pseudoacacia), Norway spruce (Picea abies), red oak (Quercus rubra) and hybrid poplars. In places these non-native species form independent stands. Of the typical alluvial plain species we can find fluttering elm (Ulmus laevis) and small-leaved elm (Ulmus minor), but mostly in the lower levels and a few examples of black poplar (Populus nigra). The helleborine Epipactis albensis grows here on dozens of microlocalities and is closely bound to these poplars, even if they are not of natural origin. The violet helleborine (Epipactis purpurea) also grows here. In the alder carrs we can find small populations of greater spearwort (Ranunculus lingua) and tufted loosestrife (Naumburgia thyrsiflora). 

A significant element of these near-natural forest stands are the xylophagous insects which develop on the dead and rotting wood. Notable examples are flat bark beetle(Cucujus cinnaberinus), the hermit beetle Osmoderma eremita and stag beetle (Lucanus cervus). The NNR was also a significant butterfly locality in the past. The disappearance of the rarest species – clouded apollo (Parnassius mnemosyne) and scarce fritillary (Euphydryas maturna) in the 1990s is probably connected with the transformation of the forest towards a commercial high-forest type. On the other hand, the shaded forest suits the black storks (Ciconia nigra) which nest here.

Another significant element contributing to the biodiversity in the reserve are the pools and oxbow lakes. The fairy shrimp Siphonophanes grubii and the tadpole shrimp Lepidurus apus can be seen in many of the pools in the springtime. Interesting aquatic vegetation is found in the deeper pools and ones which are exposed to more sunlight. The rarest plants growing here are the white-water lilies (Nymphaea candida, Nymphaea alba). Water violets (Hottonia palustris) can be seen in the shallower pools and small growths of water germander (Teucrium scordium) are occasionally found in the reedbeds.

Meadow communities can be found scattered throughout the Libický luh alluvial forests and range from sedge stands to mesophilous oatgrass (Arrhenatherum association) meadows. Less common are alluvial foxtail (Alopecurus) meadows and continental inundated meadows on which typical but rare herbs such as marsh pea (Lathyrus palustris), common meadow-rue (Thalictrum flavum) and Cnidium venosum can be found.

The current condition of the territory is mainly the result of the regulation works on the Labe river. Straightening and deepening of the river channel restricted the regular flooding, which was the source of regular formation and renewal of the pools and of the maximal variety of biotopes. Some of the sediments which were dredged out of the river were also left in Libický luh. At the turn of the 20th century the forest stands in Libický luh still had the character of softwood alluvial forest with predominant willows, alders and poplars. At that time, extensive areas were planted with oaks, which formed the basis for the current appearance of most of the forest stands. The vegetation in many of the pools was seriously damaged by insensitive fishery management, including stocking of herbivorous fish species and some of the pools were also used for, and damaged by, breeding of semi-wild ducks. Parts of the meadows were either ploughed up or abandoned, both of which led to their gradual degradation. The D11 motorway runs along the northern edge of the NNR.