Central Asia

Saxaul Forests as a Carbon Sink

„Climatic relevance of Saxaul and the carbon sink potential of cold-winter deserts and semi-deserts in Central Asia“

 

Two species of Saxaul (Haloxylon ammodendron and Haloxylon aphyllum) are the dominant plants in the cold-winter deserts and semi-deserts of Central Asia.
Ranging from Turkmenistan through Uzbekistan and Kazakhstan to Northwest-China (Xinjiang) and Mongolia, the two species of Saxaul cover an area of approximately 450,000 square kilometres.
In semi-arid and arid ecosystems, large quantities of biomass are sequestered belowground, and the dry climate conditions lead to a mid-range removal of carbon from the global cycle. Therefore, cold-winter deserts act as carbon sinks (C-sinks). Besides functioning as a C-sink, the Saxaul vegetation of the Central Asian semi-deserts takes on a multi-functional key role in offering additional benefits to the ecosystem. These include the stabilisation of lightly eroded soils, a reduced risk of sand and salt dust storms, the enrichment of phytomass and humus, and the regulation of the ecosystem’s water balance through shade formation and small-scale evapotranspiration.

 

Despite numerous desert-specific research projects by Soviet institutes the carbon fixation potential and the resulting climatic effect of Saxaul vegetation has not been satisfactorily quantified to date. The degradation of the ecosystem through overgrazing and timber harvest (within their entire range, Saxaul forests serve as valuable pastureland and a source of alternative fuel) likely leads to a significant decrease of the possible carbon fixation potential.

The main goal of the project was the quantification and evaluation of the climatic relevance of Saxaul vegetation and the C-sink potential of the cold-winter deserts and semi-deserts of Central Asia. Additional goals included the evaluation of the afforestation potential for Saxaul in Central Asia, the spatial evaluation of hemeroby in Saxaul stands and the subsequent limitation of the possible mitigation potential, as well as the establishment of supra-regional co-operation and consultation among the responsible administrative bodies.

 

Implemented Measures and Activities

Determination of the carbon pool and assessment of the C-sink potential of Saxaul stands by:

  1. A survey of ecosystem diversity and available biomass, both aboveground and belowground, in representative Saxaul stands in Kazakhstan, Uzbekistan and Turkmenistan.
  2. Measuring of the carbon content of aboveground and belowground biomass as well as deadwood biomass, followed by comprehensive laboratory analyses at Greifswald University.
  3. Extensive assessment of the Saxaul biomass and the carbon contents for Turkmenistan, Uzbekistan and Kazakhstan with the aid of remote sensing data.
  4. Assessment of hemeroby and utilisation pressure on Saxaul stands in the respective countries.

 

The degradation of Saxaul stands was estimated through surveys, interviews with experts, analysis of statistical data and remote proximation. The results were used to draw up recommendations for action to increase the carbon accumulation through Saxaul vegetation.

 

Co-operative Project Partners were:

the junior research group “Adaptation strategies for climate change and sustainable land use in Central Asia (Turkmenistan and Xinjiang, China)“ at the University of Greifswald; the research centre for forestry and horticulture in Uzbekistan (Republican Scientific Production Centre for Decorative Gardening and Forestry); the Institute of Botany and Ecology at Al-Farabi University in Almaty; and the National Institute for Deserts, Flora and Fauna in Aschgabad, Turkmenistan.

 

 

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