EPOW - Ecology Picture of the Week

Hardiest of the Asian Deserts

Black Saxaul (Haloxylon ammodendron), Family Amaranthaceae
Gobi Desert, Mongolia

Explanation:  Enduring the summer heat, winter freeze, and drained and dried sandy soil, is this hardiest of trees of the Asian deserts.  This is called a black saxaul, and is one of three species of this genus, all desert dwellers of central Asia.

This amazing and unassuming plant is strictly called a "psammophyte" ("SAM-oh-fite"), meaning a plant that thrives in sandy conditions.  

  

A temporary waterhole adorns the open sands of the Gobi Desert.
The black saxaul needs no such open water source, however, to thrive.

  
It has been planted in northern China on a large scale to help fight desertification there.  And the Uzbeks have planted it in the Aral Sea to stop the spread of toxic salts after the Aral Sea dried up.

Its thick, gnarled bark stores water, although because of the twists of its grain, it is mostly useless as a source of lumber.  However, black saxauls are largely the only tree -- and only source of fuelwood -- in much of the Gobi desert.  

The species has declined in distribution significantly in recent decades, perhaps owing to exploitation by people and to regional climate warming that continues to unduly increase the aridity of the tree's environment beyond even the tree's capacity to adapt.

  

The black saxaul can grow vertically, angled, or even horizontally,
strengthened by its twisted trunk.

This spot hosted a "black saxaul forest," to so speak,
maybe more appropriately called an open desert woodland,
with many saxaul trees scattered across this particular area
of the Gobi Desert of southern Mongolia. 

This tree is not just a survivor.  Black saxauls have been used for their bark's water content; its wood used for campfires; and its foliage used as fodder for livestock.  It serves as a structure for birds and reptiles to nest and hide.  The same-named saxaul sparrow feeds on its seeds.  And other sources suggest that its roots are used by herbalists for treating a variety of ailments.  

 

The stems and "foliage"
are green and photosynthetic, 
growing in segments,
appearing more like
horsetail (Equisetum) or
Mormon tea (Ephedra)
of the American 
southwest deserts.

  

 

Information:
     Yu, T., C. Ren, J. Zhang, X. He, L. Ma, Q. Chen, Y. Qu, S. Shi, H. Zhang, and H. Ma.  2012.  Effect of high desert surface layer temperature stress on Haloxylon ammodendron (C.A. Mey.) Bunge.  Flora - Morphology, Distribution, Functional Ecology of Plants 207(8):572-580.