Stanisław Kędzia

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 basing on interpolation and extrapolation of data from meteorological stations. Thanks to the application of Onset HOBO data loggers, the measurements of air temperature were carried out in selected 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 investigations 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 determined 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.

Glacial Erosion in the Abisko Mountains: Kärkevagge and Vassivagge, Northern Sweden

Abstract This paper discusses direct current resistivity soundings and geomorphological studies of Quaternary deposits in two glacial troughs in the Abisko Mountains of northern Sweden. The subject of the fieldwork is the depth of Pleistocene glacial erosion. Studies were carried out in 1998 and 2003 in the Kärkevagge and Vassivagge. The estimated thickness of Quaternary deposits and bedrock properties are discussed in the broader context of glacial erosion studies in the Abisko area. Geophysical and geomorphological studies suggest that the depth of glacial erosion was highly differentiated from –190 m in the Torneträsk basin to the metric overall erosion on the upland plateau. In medium‐sized valleys several kilometres long, erosion depth measures 30–50 m. Present‐day stream channel patterns reveal a strong relation to the bedrock configuration in valley floors