ISSN 1067-4136, Russian Journal of Ecology, 2007, Vol. 38, No. 4, pp. 223–227. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © S.G. Shiyatov, M.M. Terent’ev, V.V. Fomin, N.E. Zimmermann, 2007, published in Ekologiya, 2007, Vol. 38, No. 4, pp. 243–248.
In a previous study, we analyzed the spatial distribu-
tion of different types of tundra communities (individ-
ual trees in the tundra, sparse tree growth, open forest,
and closed forests) in the Polar Urals in the 1910s,
1960s, and 2000s (Shiyatov et al., 2005). During the
past 90 years, open and closed forests in the timberline
ecotone have markedly expanded due to natural affor-
estation of the tundra and increase in the density and
productivity of existing forest stands. The upper bound-
aries of sparse tree growth, open forests, and closed for-
ests on many mountain slopes have ascended, but accu-
rate data on the extent and rate of their displacement is
The purpose of this study was to quantitatively
assess the altitudinal and horizontal shifts of the upper
boundaries of pure larch (
and closed forests between 1910 and 2000, i.e., in the
period with favorable climatic conditions for tree
growth. Areas with sparse tree growth and individual
trees in the tundra were not considered because of dif-
ﬁculties in determining their boundaries in the ﬁeld.
The mapped area included in the analysis (approxi-
mately 50 km
) is in the timberline ecotone, extending
from the eastern spur of the Rai-Iz massif in the north
to the Orekh-Yugan stream in the south. Low-angle
slopes prevail there, and the position of the timberline
is determined mainly by climatic factors and, in partic-
ular, wind at the foothills of Mts. Tchernaya and
Malaya Tchernaya, and ambient temperature on the
southern slope of Rai-Iz (Shiyatov, 1970).
We apply the term “timberline ecotone” to the tran-
sitional belt of mountain vegetation between the upper
limit of closed forests and the upper limit of single tree
growth in the tundra. Today, this ecotone in the study
region lies at elevations ranging from 140 to 560 m
a.s.l. Closed and open larch forest grow at the bases and
in the middle parts of slopes, with their upper bound-
aries passing at the average elevations of 230 and 260 m,
respectively. According to our classiﬁcation, these
terms refer to communities in which the average dis-
tances between trees are less than 7–10 m and from 7–
10 to 20–30 m, respectively. More detailed data on the
study region and cartographic methods were published
previously (Shiyatov et al., 2005).
The altitudinal and horizontal shifts of the upper
boundaries of open and closed forests were quantita-
tively assessed using the ARC/INFO geographic infor-
mation system (GIS) (ESRI Inc., United States) with
the AML language and ﬁeld-derived thematic geobo-
Altitudinal and Horizontal Shifts of the Upper Boundaries
of Open and Closed Forests in the Polar Urals in the 20th Century
S. G. Shiyatov
, M. M. Terent’ev
, V. V. Fomin
, and N. E. Zimmermann
Institute of Plant and Animal Ecology, Ural Division, Russian Academy of Sciences,
ul. Vos’mogo Marta, 202, Yekaterinburg, 620144 Russia;
Swiss Federal Research Institute WSL,
Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland;
Received April 7, 2006
—In the Polar Urals (the Rai-Iz massif and Mounts Tchernaya and Malaya Tchernaya), altitudinal and
horizontal shifts of the upper boundary of open and closed larch forests in the 20th century have been studied.
Spatiotemporal parameters of these shifts have been assessed with the aid of the ARC/INFO geographic infor-
mation system (ESRI Inc., United States), using our original large-scale geobotanical maps showing the distri-
bution of different types of forest–tundra communities in the early 1910s and 2000s. The results show that tree
vegetation has been actively expanding to higher elevations over the past 90 years. On average, the upper bound-
aries of open and closed forests have ascended 26 and 35 m and shifted horizontally 290 and 520 m, respectively.
These shifts have been conditioned by climate warming and increasing humidity observed since the 1920s.
: timberline ecotone, altitudinal and horizontal shifts of upper boundaries of open and closed forests,
climate warming, increasing humidity, geographic information system,
, the Polar Urals.