The Borečský vrch Hill NNM (446m) is a mostly forested trachyte knob. The protected area lies close to the town of Lovosice in the Ústecký kraj – Ústí nad Labem Region and within the České středohoří Mountains PLA. The monument covers an area of 18.7ha and was declared in 1951. The most distinctive feature on the block field are the ventaroles – artificially widened openings or fissures on the upper slopes from which warm, damp air flows out in winter time. The snow around these ventaroles always melts as the temperature difference between these air flows and the surrounding air can be up to 16°C in winter.
The Boreč massif is a morphologically perfectly built knob of sodalite trachyte, with a complicated labyrinth of fissures inside. Through the summer the hill acts as a temperature accumulator, meaning that it is considerably warmer than the surroundings when winter comes. Among the clumps of the Irish saxifrage (Saxifraga decipiens), which grow at the foot of the slopes, we can find openings where air is sucked in, warmed up and made damper as it passes up through the fissures in the hill. This lighter air then passes out of the openings at the summit of the hill. In frosty weather a misty haze hangs over the upper openings of the fissures. When spring arrives the air flow reverses and cold air flows down through the hill and out through the vents at the foot of the talus, where icicles can be seen until late spring.
The occurrence of a range of plant species here is bound to the specific microclimate on the hill. These include the liverwort Targionia hypophylla, which cannot endure temperatures below 0°C. The slopes of the Borečský vrch Hill have a very rich and varied vegetation cover, which includes rare and protected plants such as eastern pasque flower (Pulsatilla patens), large pink (Dianthus superbus), miniature tall bearded iris (Iris aphylla), northern rock-cress (Cardaminopsis petraea) and Alpine forget-me-not (Myosotis stenophylla).
The fauna of the territory consists mostly of forest species and its composition is also influenced by the specific microclimate on the hill. Among the vertebrates we can observe large numbers of fire salamanders (Salamandra salamandra) here after a rainy day. Among the invertebrates, the molluscs have been researched and some of the beetles. The most significant beetle species which has been recorded here is the ground beetle Pterostichus negligens, which lives in the talus fields and is a glacial relict which has survived from the ice ages to the present day.
The forests on Borečský vrch are predominantly natural, deciduous stands and talus and tavine stands with limes, maples and ash. The southern slopes are covered by thermophilous oakwoods with a rich shrub layer. On some sections of the talus on the northern slope we can find birches and rowans, with hazels growing at the foot of the slope.
The Lovoš-Boreč themed trail passes through the monument and this section of the trail is especially attractive on frosty winter days. The territory is also included as a proposed Site of Community Importance under the Natura 2000 network to protect the eastern pasque flower.