Olsy Płoszyckie

Olsy Płoszyckie is a forest nature reserve of about 141 hectares in Lelis commune, Ostrołęka County, in the Kurpie Forest of Masovia. It was established in 1997 to protect a well-preserved complex of alder carr in the Rozoga river valley, valued for its fauna, plant communities and flora^[1].

Forty-nine bird species breed or probably breed here, including the common crane and the lesser spotted eagle, both strongly threatened; the Tengmalm's owl is also very rare in Poland^[2]. Beaver lodges are numerous in the reserve and the adjacent water body^[1].

Fertile black-currant alder carr covers about 94 hectares and ash-alder riparian forest about 43 hectares, with a small patch of pine forest. 199 vascular plant species have been recorded, and spurge laurel is very common and protected^[1]. The alders are about 70 to 90 years old^[2].

The reserve occupies the valley of the Rozoga river, where the waterlogged ground that alder carr needs persists^[1]. It is a lowland wetland, not a rocky or hilly landform.

North-eastern Masovia has a temperate climate with cold winters and warm summers. The reserve's alder carr depends on the high water levels of the valley, which fall and rise with the seasons.

The reserve is in the Kurpie Forest, with the forest settlements of Płoszyce to the south and Grale to the north on its edges, and the village of Płoszyce about 4 km away^[1]. Black alder wood from stands like these has been used for plywood and fencing^[2].

The reserve was created in 1997 by a ministerial order. Its protection plan was prepared by the National Fund for Environmental Protection in Warsaw, and the Ostrołęka Forest District owns and manages it^[2].

The Olcha educational trail, about 4 km long with 14 information stops, runs through the forest next to the reserve. Stops cover the reserve, forest ecology, black alder, spurge laurel, beavers at a pond on the trail, and the lesser spotted eagle, which sometimes flies over the forest^[2].

The trail lies along the Nasiadki–Golanka road, about 35 km from Ostrołęka, and is open to the public. A parking area is used for recreation, and local schools use the trail for lessons^[2].

The reserve protects some of the best alder carr in the area and the birds and beavers that depend on it, including two strongly threatened species. The Ostrołęka Forest District manages it and runs the educational trail beside it to teach visitors about forest ecology and protection^[2].