Uzbekistan: Rehabilitation of Desert Rangelands Affected by Salinity, to Improve Food Security, Combat Desertification and Maintain the Natural Resource Base - Combating Desertification in Asia, Africa and the Middle East - page 252

Spring Summer Autumn

a

11% 6%

7%

89%

94%

93%

b

9%

20%

26%

74% 80%

91%

c

30%

19%

45%

70%

55%

81%

C3 C4

Fig. 13.7 ´ 4 types of photosynthesis in different plant associations

( a - xerophytes, b - xerohalophytes, c - haloxerophytes) during vegetation season

Ratio of species with ´ 3 and

as H . aphyllum , S . paulsenii , H . hispida accumulate 20-90 g kg 1

of sodium in

green above ground parts. The representatives of ´ 4 species ( C . lanata , Sueda

sp.) of haloxerophyte plant association are capable to accumulate up to 300 g
kg 1 of sodium. Proportion of species with C 3 and C 4 type of photosynthesis
at the three plant communities considerably differentiated along the spatial and
temporal scales (Fig. 13.8 a, b). The highest density of xerophyte and xerohalophyte
plant communities belongs to C 3 species consisting of 89-94 % and 74-91 %,
respectively. The ratio of C 4 plants showed smaller values than C 3 plants for
both plant communities. These plant resources have not yet been widely used as
part of the arid production system of Uzbekistan by the pastoralists and farmers.
Previous studies have shown that many wild halophytes grow well in association
with a variety of salt tolerant traditional crops and often provide severe competition
to tree/shrubs species, both in natural and improved pastures both on saline and
disturbed mine sites (Toderich et al. 2007 , 2008 ).
Investigations in 2011 identified that the ratio of C 3 and C 4 plants in vegetation
communities differs both along the salinity gradient and on seasons of the year.