A lowland river-valley forest reserve protecting rare alder wetlands and endangered birdlife in the Mazovian countryside.
Dolina Mławki Nature Reserve
Dolina Mławki Nature Reserve is a forested nature reserve in north-central Poland, designated to preserve a large, floristically typical complex of alder and ash-alder swamp forest along the Mławka River valley. Established in 1994 on land belonging to the village of Grądek in Gmina Szreńsk, Mława County, Masovian Voivodeship, the reserve covers roughly 147 hectares of lowland wetland woodland.
The protected area lies within the administrative forests of the Ratowo forestry district of the Dwukoły Forest Inspectorate and is administered primarily for scientific and educational purposes. Its alder-dominated canopy, mixed with birch, ash, elm, spruce, and brittle willow, supports a wide range of wetland plant species, including 192 recorded vascular plants, while its damp, structurally varied habitat hosts a rich bird community of around 57 species.
The reserve is notable for combining high conservation value with a strong educational mission. Several breeding and threatened bird species depend on its mosaic of swamp forest, wet clearings, and riparian corridors, making it an important site for wetland-forest conservation in the Masovian region.