The UNESCO International Biosphere Reserve “Western Polesie” was established in May 2002. It is the second in the world (after the Eastern Carpathians) three-state Biosphere Reserve. It covers the border regions of Polesie at the junction of the borders of three countries – Belarus, Poland and Ukraine. The International Biosphere Reserve “Western Polesie” covers within the Polish borders a large part of the Łęczyńsko-Włodawska Plain and small fragments of Sosnowicka Zaklęsieć, Parczewska Plain, Garb Włodawski and Chełm Hills.

It is the area of the largest group of lakes in Poland, not of glacial origin. Small differences in height and shallow groundwater deposition cause that there are many wetlands here – swamps and peat bogs. The area of the reserve is situated at the intersection of two important European ecological corridors. The first of them, with a latitudinal course, connects Eastern and Western Europe through Polesie, the Wieprz River valley and the Vistula valley; the second – runs longitudinally along the Bug river valley and connects through the valleys of the Dniester (in the south; Ukraine), San and the Vistula valley, the Pontic (Black Sea) Region with Northern Europe. The location in the ecological junction makes the Western Polesie an area of a true mosaic of plant habitats and communities. All types of bogs can be found here, including rare carbonate bogs, which have exceptional natural values. In this area, small groups of tundra and lasotundra have been preserved, located farthest to the south-west in Europe. The natural uniqueness of West Polessye is evidenced by the accumulation of northern plant species (approx. 150 species), and the presence of many plants in the Atlantic (25 species), East-continental (43 species) and southern (30 species) zones.

Many rare and protected plants have been found here, including the Polish “Red Book of Plants”. The peculiarities of this area include Drosera sp. Sundews, Aldrovand vesiculosa bladder aldrowanda, Betula humilis low birch, Salix lapponum Sami willow and Salix