Photo 1. The effect of the bora wind on the slopes of Mala Peša in the area above Kripanjski Put: bent in the direction of the bora wind, this whitebeam tree is a sign that the bora is a frequent and strong wind here (Photo by Ana Randić and Marko Randić)
NARROW-LEAVED MOOR GRASS – A BIO-INDICATOR OF THE FREQUENCY AND STRENGTH OF THE BORA WIND?
Grasslands exposed to the bora wind stretch across the area above Kripanjski Put (Peša and Krušvica, “by the chapel”) (Photo 1). At least two abiotic features of this habitat – the bora wind and the geological substrate – have a powerful influence of the botanical composition of the grassland plant communities. The geological substrate (as well as the bora wind) drives the soil-forming processes here and we can distinguish between soil on moraines (Photos 2 and 3) and soil on solid limestones (Photo 1). On the very peak of the ridge of a glacial moraine, in a spot that was the most exposed to the gusts of the bora wind (which we witnessed at first hand, because the wind was blowing when we were there, see Photo 2), we noticed several solitary hassocks of narrow-leaved moor grass (Sesleria junicfolia), growing on the shallow rendzina soil. We could not find this resistant grass species on any of the other parts of the moraine ridge, which were covered in rock knapweed and dwarf hedge. This leads us to conclude that the narrow-leaved moor grass, a species highly adapted to the gusts and force of the frequent bora wind, could be a reliable bio-indicator of the effect of the bora wind on the botanical and floral composition of grassland.
Ana Randić and Marko Randić