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characterized by reduced richness of species, especially trees and shrubs, and, thus,
The vegetation cover of sandy deserts has a complicated spatial structure, which
forms as a result of initial heterogeneity of the micro- and mesorelief landscape due
to processes of soil denudation, salt accumulation and changing moisture content
along soil profiles. Numerous seasonal surveys done by us during 2005-2011
have identified more than 380 species of different groups of salt loving plants
(wild halophytes representing 19 taxonomical families). The study areas show a
high endemism in plants (about 3.4 % from total species). Most noticeable is the
relative richness of the Chenopodiaceae with nearly 33 %, equivalent only with
Australia's chenopods. It is also quite rich in Asteraceae (20 %), Poaceae (11 %);
Fabaceae and Brassicaceae (about 11 %). Species belonging to Polygonaceae,
Plumbaginaceae, Zygophyllaceae, Cyperaceae account for a smaller share (3-5 %),
whereas, Eleagnaceae, Plantagainaceae and Frankeniaceae make up an even smaller
part (
1.0 %) of rangelands halophytic pastures. Among cited plant resources there
is a number of native and exotic halophytes both C
3
and C
4
plants suitable for
reclamation of arid and semi-arid, salt/affected and waterlogging areas that have
proven very useful in demonstration trials.
The distribution of halophytic vegetation is related to inter-specific and intra-
specific plant species competition, grazing capacity and land management. Desert
topographical features and salinity gradient are of primary importance in determin-
ing the contribution of species with different photosynthetic pathways or taxonomic
relations in forming of core ecological plant community types or vegetation units.
Relative abundance of different growth forms and different pathways vary with
seasonality of precipitations; e.g. spring-summer rainfall favors the abundance of
C4 pathways chenopods. Annual ephemerals (short-lived) and ephemeroids occur
in spring-early summer in times of moisture availability both in open rangelands
areas and/or beneath the canopy of perennial plants. Our observations show that
as results of drought impact the prevalence of open areas on rangelands increases
with aridity and many species become increasingly restricted to run-on or moisture
accumulation places. In high saline areas (named solonchaks) there is virtually no
plant cover or only limited number of salt loving (halophytes) can grow.
Based on this mapped vegetation pattern distribution (Fig.
13.6
) and on ground
data we found that there were only a few core species, which determine productivity
of rangelands of the studied biotopes/niches. Assessing the grazing potential of
degraded rangelands by mapping zonal halophytic vegetation allowed us to identify
salt pioneer plant species for each studied zone in order to initiate the reclamation
process of saline prone soils. Among frequently found species there were
Cli-
macoptera lanata
,
Kochia scoparia
,
Atriplex nitens
,
Salsola rigida
,
Halothamnus
subaphylla
(Chenopodiaceae),
Glyzhyrrhyza glabra
(
Fabaceae
) annual and peren-
nial species, growing well both on salty crusts (solonchak-alkaline soils), on clay
and gypsum deserts, on takyr and high saline sandy soils . Therefore, we consider
these species as a model plant for calculation of rangeland productivity both on
virgin area and under cultivation (agro-silvi pastoral model) by using supplement
irrigation with low quality water and application of fertilizers (Toderich et al.
2008
).
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