Nicola Arndt und Matthias Pohl - Neobiota

As shown in Table 2 there is a good correlation between zonal positions and temperature sums. The
eight stations situated in the arctic polar desert zone have extremely low temperatures. This zone is
developed with temperature sums from 0 to 5 o C, the northern arctic tundra zone in the range 5-11 o C,
the middle arctic tundra zone in the range 11-18 o C, the southern arctic tundra zone in the range
18-27 o C, and the arctic shrub tundra zone between 27 and 36 o C. The ranges increase gradually from
5 to 9 o C, through the various zonal units. This is not equal, but one degree change can have more
easily observed effects in an extremely cold area than in the southern parts of the Arctic.
A polynominal trend line for the correlation between the zonal positions and temperature sums vs.
mean July temperatures presents the data in the best way as the ranges in the zonal units are not
equally large (Figure 2). However, r 2 values from the linear trend line shows a considerably higher
correlation between zonal position and temperature sums (r 2 = 0.957) than with mean July
temperatures (r 2 = 0.914).
These data support the subdivision of the Arctic into five units. A lumping of NATZ and MATZ as
proposed by WALKER (2000), would make this unit span about 13 o C in biotemperatures, contrasting
the other units by being climatically about twice as large. A similar lack of balance would result from
uniting the two southernmost zones as proposed by some Russian authors (e.g. MATVEYEVA &
CHERNOV 2000) and BOHN et al. (2000).
The arctic treeline has traditionally been considered to follow a mean July temperature of 10 o C, which
has also been considered to be a definition of the Arctic. However, the treeline occurs probably in the
range 8-9 o C in Iceland (data not processed yet), near 9.5 o C in coastal Finnmark, near 10.5 o C at the
coast of the White Sea, and is near 12-12.5 o C in the most continental parts of the study area.
However, the temperature sum varies around 36 o C, and is a much better criterion as there is no
general variation between oceanic and continental areas. The only previous study focusing on this
aspect is the one by YOUNG (1971), who had similar conclusions, but only had available data from 16
meteorological stations in the present study area.
Figure 2: Correlation between temperature sums and zonal positions of arctic meteorological stations in Europe.
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