Distribution Patterns of Vegetation as a Fundamental Factor in Mongolian Ecosystems

Abstract

In central Mongolia, south of Ulan Bator up to Dalanzadgad, vegetation is classified into three zones from north to south: the forest-steppe, steppe, and dry steppe zones, with trees and shrubs specific to each of these zones. The deciduous conifer Larix sibirica is the dominant tree in the forest-steppe zone; the shrub Caragana microphylla (Fabaceae), which fixes nitrogen, is widespread in the steppe zone between Ulan Bator and Mandalgobi; and two shrubs, Caragana stenophylla on sandy soils and a mixture of Kalidium foliatum and Reaumuria soongorica on silty soils, dominate the dry steppe zone between Mandalgobi and Dalazadgad. In the steppe and dry steppe zones, species of Allium and Stipa differ between zones, with Allium mongolicum and Stipa glareosa, and Allium polyrrhizum and Stipa gobica, in the former and latter, respectively. In each zone, shrubs that are palatable for livestock are decreasing and becoming extinct through overgrazing by livestock for a long time. In degraded pasture, Artemisia species dominate, changing from Artemisia dracunculus and Artemisia adamsii to Artemisia pectinata with decreasing altitude. Desertification does not advance in the sense of the complete loss of vegetation, but is progressing in the sense of vegetation and soil degradation.