Environmental Engineering Reference
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where
P
is a share of species group,
x
is the
time from the start of self-organized vegetation
(years),
ʱ
and
ʲ
are coeffi cients, and
A
and
a
0 are
empirically set minimum (
a
0) and maximum (
A
)
levels of function. Coeffi cients were found by a
method of iterative numerical estimation.
Coordinates of critical points of infection of
functions (
x
lower
and
x
upper
points), marking the end
of the rapid changes of function values, were
found in accordance with recommendations by
Vorobeychik et al. (
1994
).
Selivanov et al.
1964
), but is higher than the
known estimates for the northern deserts of
Kazakhstan (65 %; Eleusenova and Selivanov
1973
). The greatest number of non-mycorrhizal
species, among indigenous for heap, belongs to
the Brassicaceae and Chenopodiaceae and myc-
orrhizal ones mainly include representatives of
the Asteraceae and Poaceae (Table
2
). Such dis-
tribution is to be expected, since this is observed
often (Selivanov
1981
; Wang and Qiu
2006
).
The dynamics of plant species of different
mycorrhizal status during self-organized vegeta-
tion of dump is described in Table
3
. At plots I
and II the fi rst descriptions were made in the
beginning year of overgrowing (1978). Therefore
a increase of the total number of recorded species
at these plots was well expressed (from 4 to 21
species in 1978 to 28-33 species in 2006).
Dumping of the plot III was done in 1971, that is
why observations of the fi rst dynamic stages of
overgrowth were not carried out, therefore at this
plot a increase of the species number was not
expressed (Table
3
).
On plots I and II during the fi rst 3 years of
observations in varying degrees, the number of spe-
cies of all categories of mycotrophy increased. And
over the next 26 years, only the number of mycor-
rhizal species increased, while the number of non-
mycorrhizal and changeable mycorrhizal species
during this time reduced or remained unchanged.
For plot III during the observation period, an almost
double decrease in the number of species of all
groups of mycotrophy and, accordingly, the total
number of plant species was registered - from 67
species in 1978 to 36 in 2006 (Table
3
).
Grass ecosystems are characterized by consid-
erable fl uctuation in species composition (Mirkin
and Naumova
1998
). During the observation
period, properties of ecotopes infl uencing the
settlement and survival of plants changed (con-
solidation of substrates and increase of saliniza-
tion were registered) (Kuprijanov and Manakov
2008
). Therefore it is more justifi ed to analyze
not absolute number of different plant groups but
their share. In preparation for such comparison
we have used different durations of the vegeta-
tion development on plots I-II on one hand and
on plot III on another (Fig.
3
).
3
Results
By the time of the last registration in 2006, plots I
and II were overgrown for 29 years, and plot III
for 36 years. During this time, at the dump there
were formed the communities are less diverse in
the fl oristic terms compared with the zonal plant
communities. The total projective cover of plants
in the last accounting period in 2006 was
30-40 %. High participation of Brassicaceae and
Chenopodiaceae and less abundance of gramine-
ous, forbs and ephemeroids is characteristic fea-
ture of dump's plant communities (Kuprijanov
and Manakov
2008
). The presence of halophilic
species such as
Bassia
,
Halimione
,
Limonium
,
Petrosimonia
,
Salsola
,
Saussurea
, and
Suaeda
refl ects expressiveness of salinization processes,
particularly evident on plot III.
From the 97 registered species on three plots
for 85 species mycorrhizal status was set. Species
for which on the literary data failed to fi nd the
characteristics of the relationship with mycorrhi-
zal fungi most often refer to the Polygonaceae
(three out of four recorded species of the family)
and Chenopodiaceae (4 of 13 registered species
of the family). A total of non-mycorrhizal are 19
species of plants, 17 species are facultatively
mycorrhizal, 47 form arbuscular mycorrhizas,
and 2 woody plants species form both arbuscular
endomycorrhizas and ectomycorrhizas. Thus,
78 % of species for which the type of interact
with mycorrhizal fungi is set have mycorrhizal
colonization. This value (78 %) is less than esti-
mates of the share of mycorrhizal species in the
subzone of northern forest steppe (90 %;
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