Jacek's Bog

The Bagno Jacka Nature Reserve is a peatland protected area located in Warsaw, within the Wesoła district and the municipality of Zielonka. It was established on September 21, 1981. Covering an area of 19.76 hectares, it is situated in the Okuniewsko-Rembertowski Forest, near dunes along the Warsaw-Węgrów road. Although the name has been known since after World War II, its origin remains unclear – older residents of Wesoła remember it as the "Bartek" bog. The reserve consists of various water bodies and areas covered with characteristic peatland flora, including swamp birch forests, various reed beds, as well as low and high peat bogs. A total of 345 species of vascular plants have been recorded here, including many protected species such as the ostrich fern and the round-leaved sundew. Although the reserve is home to rich fauna, with 136 bird species and numerous mammals and reptiles, its ecosystem faces challenges such as declining groundwater levels and the expansion of invasive species. In the 1980s, birch trees proliferated, affecting vegetation diversity, while in 2011, heavy rainfall significantly raised water levels, contributing to the regeneration of the marsh. The area was once exploited for peat extraction, leaving traces in the form of old mounds and embankments. Culturally, the site gained prominence as a filming location – Andrzej Wajda's film "Brzezina" (The Birch Wood) was shot here. The Bagno Jacka Reserve is a vital part of the local natural heritage, requiring protection and responsible management to preserve its unique ecosystem and biodiversity.