Agriculture Reference
In-Depth Information
Chapter 8
A C OLD S ITE L OCATED B ELOW THE L IMIT OF
D ISCONTINUOUS A LPINE P ERMAFROST : P LANT
C HARACTERISTICS AND S OIL N UTRIENT D YNAMICS
D URING THE W INTER S EASON
Michele Freppaz a,1 , Luisella Celi a , Fulvia Rosso a , Veronika Stöckli b ,
Marcia Phillips b and Ermanno Zanini a
a University of Torino, Di.Va.P.R.A. - Laboratorio Neve e Suoli Alpini, 44 Via Leonardo
da Vinci, 10095 Grugliasco (TO), Italy
b Swiss Federal Institute for Snow and Avalanche Research,
7260 Davos Dorf, Switzerland
A BSTRACT
Exceptional occurrences of permafrost exist in the forest belt well below the limit of
discontinuous alpine permafrost. There are several such sites in the Alps, all steep scree
slopes located at the foot of high limestone cliffs. A particularly interesting and important
characteristic is that they are vegetated with subalpine vegetation and that some plants
display signs of severely limited growth. Research carried out in the last years has
demonstrated that the ground is not frozen as a result of a particularly cold microclimate
at these locations, but that permafrost is present due to a particular air circulation
phenomenon. Under these conditions, soil organic matter accumulates due to the slowing
down in degradative processes of plant residues. Consequently, the nutrient availability to
plants may be limited and contribute to the reduced plant growth, although scant attention
has been devoted to this topic.
To determine vegetation and soil characteristics, tree height, tree ring width
measurements and soil analysis were performed in two contiguous areas differently
affected by frost conditions in Western Switzerland and characterized by different growth
of trees: (I) dwarf trees; (II) reference trees. Near surface soil temperature in the two sites
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