ISSN 1067-4136, Russian Journal of Ecology, 2007, Vol. 38, No. 6, pp. 440–443. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © V.S. Mazepa, N.M. Devi, 2007, published in Ekologiya, 2007, Vol. 38, No. 6, pp. 471–475.
The Siberian larch (
at the limit of its distribution in high-mountain regions
in the Urals has a number of adaptive properties provid-
ing for its successful existence under extreme climatic
and edaphic conditions (Gorchakovskii and Shiyatov,
1985). One of these features is the ability to grow in dif-
ferent life forms. The development of such trees has
been studied insufﬁciently, although Goroshkevich and
Kustova (2002) described some mechanisms of struc-
tural adaptation of forest trees to extreme environmen-
tal conditions in the mountains and their place in the
system of life forms. Such studies are important for
assessing the response of forest ecosystems to climatic
changes, which is a fundamental problem of global and
On the eastern macroslope of the Polar Urals (in the
Sob’ River basin), the timberline ecotone is occupied
mainly by pure larch communities differing in density.
Open larch forests and sparse tree growth ascend to ele-
vations of 300–400 m a.s.l., while single trees occur in
the tundra even at 500–550 m. Their altitudinal distri-
bution depends on air temperature in summer, wind
conditions in winter, and the presence of steep rocky
slopes (Shiyatov et al., 2006). Matlike, stem–shrub,
prostrate (procumbent), multistemmed, and single-
stemmed ecomorphs are distinguished in the larch. In
the study region, many larch trees are multistemmed,
each resembling a clump of trees with several vertical
stems (Fig. 1). Such trees appear due to the formation
of erect stems in the prostrate ecomorph and usually
grow in windswept habitats.
In this study, we show that the development of ver-
tical stems in prostrate and stem–shrub ecomorphs of
Siberian larch takes place mainly in climatic periods
with conditions favorable for tree growth.
The material was collected in the timberline ecotone
on the southeastern slope of the elevation whose sum-
mit (312.8 m a.s.l.) is located 4 km east of Mount Tch-
ernaya, in the Engayou–Kerdomanshor interﬂuve
49'27.90" N, 65
32'21.23" E). The position of the
timberline in this locality is determined mainly by
wind. Model multistemmed trees were selected in the
course of root surveys in areas where this life form was
more frequent. In these areas, Siberian larch trees grow
at distances no less than 50–60 m from each other. We
chose 23 trees of different sizes (from smallest to larg-
est), with different numbers of vertical stems, which
had no signs of suppressed growth or mechanical dam-
age. All these trees were photographed, schemes of
branching of their stems during plagiotropic growth
were drawn, and the height of each stem and its diame-
ter at the base of the vertical part were measured.
The trees were then rooted out, as studies on the struc-
ture and distribution of different aboveground and
underground phytomass fractions in multistemmed
trees were performed in parallel (unpublished data).
At the bases of the vertical parts of stems, crosscuts
were made for dendrochronological determination of
the date when the central tree ring was formed.
To estimate the time when the tree emerged, the root
system was carefully examined to ﬁnd the central tap
root and determine the location of the hypocotyl. As a
rule, it is difﬁcult to ﬁnd the growth point, as the tree
forms a large number of additional roots during life.
Rooting nodes on second-order branches submerged
into the moss–lichen layer were determined by means
of expert evaluation. When the root collar could be
detected, a crosscut was made in the corresponding
place. The corresponding parts of the root system were
sometimes dried out. In ambiguous cases, several
Development of Multistemmed Life Forms of Siberian Larch As
an Indicator of Climate Change in the Timberline Ecotone
of the Polar Urals
V. S. Mazepa and N. M. Devi
Institute of Plant and Animal Ecology, Ural Division, Russian Academy of Sciences,
ul. Vos’mogo Marta 202, Yekaterinburg, 620144 Russia
Received April 25, 2007
: Siberian larch, morphogenesis, life form, timberline.