The southern mystery of Soteska

Is cold anomaly a biotrigger or a life support for boreal Pleistocene relict species? In Soteska, Sava valley, Julian Alps, Slovenia a cold scree slope sustains an unusual plant community, usually found at altitudes higher than 1500 m above sea level. Talus slope lies close to the well-ventilated, glacier reshaped valley bottom, with northern exposure. It is an overlit forest clearing, 2185 m2 in size, surrounded with thicker birch forest, with thick undergrowth and scarce larch and spruce trees. Numerous holes between rocks act as ventilation points, sucking cold air in winter and emitting cold air, just above freezing, in the warm part of the year. Association of typically alpine species, various rhododendrons (Rhododendron hirsutum, Rhodothamnus chamaecistus) and European larch (Larix decidua) is uncommon at elevations between 490 and 590 m above sea level and is so far the only such occurrence found in Slovenia. It is famous for being one of the most southern European habitats of twinflower (Linnaea borealis), a flower presently mainly found in subarctic, boreal, or mountainous regions of the northern hemisphere. Presence of twinflower and its habitat conservation was the main reason for a project of ice temperature measurements began in 2012. Air temperatures were measured in different locations and different distances from the ground, in cold anomaly and in the neighbouring forest. Presented temperature measurements will try to correlate the cold scree conditions with the peculiar habitat, give relation with possible ice cave occurrence and act as base for protected area management, mainly regarding the interaction with critical infrastructure.