Vegetation responses along environmental gradients on the Ordos plateau, China

The Ordos plateau is a unique ecotone and is a focal region for the campaign to reduce or reverse desertification in China. This paper explores the relationship between vegetation and environmental gradients on the Ordos plateau based on a field survey of species distribution, vegetation distribution patterns, plant community structure, ecophysiological properties, and soil water content along an environmental gradient. The vegetation on the Ordos plateau may be divided into three types from east to west: steppe (eastern part), desert steppe (middle part) and steppe desert (western part). From east to west, precipitation declines significantly (from 400 mm to 150 mm). The spatial distribution pattern of vegetation at different sites was random. The density of shrub islands decreased from east to west, and their height and diameter were negatively correlated with precipitation. From east to west, the transpiration rate increased as temperature increased. Stomatal conductance was positively correlated with percentage of sunshine hours and negatively correlated with temperature. Water-use efficiency was positively correlated with average annual precipitation but negatively correlated with increasing percentage of sunshine hours. The results suggest that for effective revegetation, highly drought-tolerant species, such as Caragana tibetica and C. stenophylla, should be used and a lower percentage of vegetation cover expected (30–40%) in the western half of the Ordos plateau. In the eastern half, moderately drought-tolerant species, such as Artemisia ordosica and C. korshinskii, could be used and a higher percentage vegetation cover expected (40–50%).