Geographia Polonica (2011) vol. 84, iss. 1
The influence of relief on microclimate and location of the upper tree-limit
In the hitherto works concerning the course of the upper tree-limit or mountain pine-limit and their relation with mean annual temperature, the limits of vegetation horizons were determined much more precisely than the location of isotherms - the latter were determined bas-ing on interpolation and extrapolation of data from meteorological stations. Thanks to the applica-tion of Onset HOBO data loggers, the measurements of air temperature were carried out in select-ed sites at the upper tree-limit in Sucha Woda Valley in the Tatra Mountains. The measurements were conducted every hour during 4 months in warm period in 2007. The measurement sites were located in different land reliefs of different exposition. The lowest temperature was recorded in the depression of a channel shape located about 100 m below the other sites. Also in the next site located in a concave land form - the bottom of the Czarny Potok valley, the recorded temperature was lower than in the sites located in non-dismembered area. Despite the fact that the investiga-tions had only a preliminary character, they showed that the upper tree-limit and probably also the mountain pine-limit should not be compared with the course of mean annual temperatures deter-mined basing on interpolation and extrapolation. Only direct measurements of temperature in the field give a true picture of relation between the relief and microclimate and the upper tree-limit.
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