Popis článkuPříspěvek k problematice porostotvorné funkce jehličnatých dřevin - tlumení mrazových extrémů v horách.
[Contribution to role of conifers in stand-forming process - moderating of frost extremes in mountains] 157 - 165.
|Název článku:||Příspěvek k problematice porostotvorné funkce jehličnatých dřevin – tlumení mrazových extrémů v horách|
|Autor:||Vratislav Balcar, Ondřej Špulák, Dušan Kacálek|
We evaluated results of air-temperature investigation (October 2004 – September 2008) in several experiments situated at altitudes of 610 – 980 m above sea level in the Jizerské hory Mts. The temperature was measured automatically every hour. Sensors were fixed on wooden posts in heights of 200 cm and 30 cm above ground in a gap and in 30 cm under cnditions of canopy shelter of spruce and pine. Objective of our study was to assess climatic conditions of experiments in terms of temperature oscillation expressing severity of microclimate during vegetation period (May – September). Investigation of both incidence and duration of ground-frost events helped to assess efficiency of deciduous conifers in terms of frost-stress moderation. The best efficiency was found under conditions of microclimatically harsh locality situated in shallow mountain valley at the altitude of 860 m a.s.l. as the coniferous cover shortened frost-stress span. The ground-frost events occurrence was by 15 – 55% less frequent under conditions of coniferous crown shelter during the investigated vegetation period compared to gaps. The stress-temperature events (duration of frost at least 4 hours when minimum temperature dropped below -2°C) were by 25 – 64% less frequent compared to gaps.