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Accueil du site → Doctorat → Allemagne → 2006 → The assessment of tree species and irrigation techniques for afforestation of degraded agricultural landscapes in Khorezm, Uzbekistan, Aral Sea Basin

Rheinischen Friedrich-Wilhelms-Universität Bonn (2006)

The assessment of tree species and irrigation techniques for afforestation of degraded agricultural landscapes in Khorezm, Uzbekistan, Aral Sea Basin

Khamzina Asia

Titre : The assessment of tree species and irrigation techniques for afforestation of degraded agricultural landscapes in Khorezm, Uzbekistan, Aral Sea Basin

Auteur : Khamzina Asia

Université de soutenance : Rheinischen Friedrich-Wilhelms-Universität Bonn

Grade : Doctoral Thesis 2006

Résumé
Land degradation in the irrigation-based production systems of Uzbekistan impedes the country’s agricultural development. The adverse effects of land degradation are ubiquitous in the Khorezm Region in the north-west of Uzbekistan, as its entire irrigated area is affected by various degrees of soil salinity and hydromorphy. Afforestation, as an option to mitigate land degradation, necessitates a judicious selection of multipurpose tree species (MPTS) to make use of the otherwise unproductive land and lower the elevated groundwater table (GWT) via biodrainage.
During 24 months, root system establishment, dry matter (DM) production, quality of fodder and fuelwood, and transpiration of 10 MPTS were studied on sandy and loamy slightly saline soils under adequate irrigation. The ANOVA revealed superior biomass growth of Elaeagnus angustifolia L. and Tamarix androssowii Litv., respectively producing up to 3.9 and 3.6 kg tree-1 of utilizable above-ground DM by the age of three years. E. angustifolia showed a high potential for rapid establishment evidenced by root elongation of over 100 m tree-1. Wood of T. androssowii, Prunus armeniaca L. and Populus nigra var. pyramidalis Spach exhibited relatively high calorific values ranging from 14.4-16.2 MJ DM kg-1. Elaeagnus angustifolia and Morus alba L. offered good leaf fodder with a crude protein content of 216 and 117 g DM kg-1, respectively, which is superior to the feed quality of alfalfa hay. Mean daily transpiration, measured with a steady state porometer, differed significantly among the species (p<0.001) ranging from 4.5-5.2 mmol m-2 s-1 for P. armeniaca to 4.5-10.0 mmol m-2 s-1 for E. angustifolia. The N-fixing E. angustifolia performed best overall, followed by Populus euphratica Oliv. and Ulmus pumila L.

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