Vegetation patterns and species—environment relationships in the Gurbantunggut Desert of China

Abstract

The Gurbantunggut Desert is the largest stable and semi-stable sand desert in China, yet few data exist on vegetation pattern and species-environment relationships for these diverse desert landscapes. The sand dunes of the survey area are mainly of the longitudinal form from north to south, but checkerboard-shaped and honeycomb-shaped forms are also present, with the height of 10-50 m. We measured vegetation and soil data on north-south transects and compared them with vegetation and soil data on east-west transects. Analysis revealed that the varying trend and strength of the species diversity, dominance and cover of the plant communities in the longitudinal and transverse directions across the landscape are significantly different. The results of CCA ordination show that the microhabitats of soil organic matter (OM), soil salts (TS), sorting index (σ), topsoil water-content (SM) and pH relate to the differences in vegetation observed as differences in species assemblage from salt-intolerant ephemerals, micro-subshrubs and subshrubs to salt-tolerant shrubs and micro-arbors. The terrain (alt.) and soil texture (the contents of Mz and φ 1 ) affect the spatial differentiation of many species. However, this spatial differentiation is not so marked on transects running longitudinally with the landscape, in the same direction as the dunes. The species of the desert vegetation have formed three assemblages under the action of habitat gradients, relating to three sections running transversely across the landscape, at right angles to the direction of the dune crests. In the mid-east section of the study area the topography is higher, with sand-lands or dune-slopes with coarse particles. Here the dominant vegetation comprises shrubs and subshrubs of Seriphidium santolium and Ephedra distachya, with large numbers of ephemeral and ephemeroid plants of Senecio subdentatus, and Carex physodes in spring and summer. On the soil of the dune-slopes in the mid-west of the study area, with coarse particles and abundant TK, the plant assemblage of Haloxylon persicum, Soranthus meyeri and Agriophyllum squarrosum is developed. The species composition in the east marginal belt of the study area has similar characteristics to the mid-west section. There is no corresponding section in the north-south transects (except for the north and south margins). This is because the habitats of most plants are located in the middle of QIAN Yibing et al.: Vegetation patterns and species-environment relationships in the Gurbantunggut Desert 401 the microhabitat gradients in the north-south direction in the desert.

Vegetation coverage, species richness, and dune stability in the southern part of Gurbantünggüt Desert

“…Sang (2009) showed that, on a small scale, the vegetation coverage in the southern Gurbantu¨nggu¨t Desert was mainly affected by soil water content. Qian et al (2008) showed that on a large scale, species richness in the southern Gurbantu¨nggu¨t Desert was probably caused by the shape of the dune. From the inter-dune to the dune crest, the coverage of trees, shrubs, and herbs was mainly affected by the salinealkaline content in the soil.…”

“…The spatial distribution of the plant community is influenced by both environmental and spatial factors (Borcard et al 1992). The relationship between the vegetation and environmental factors in the Gurbantu¨nggu¨t Desert has recently been explored in several studies: these showed that the main factors causing vegetation variation were the physical and chemical properties of soils, the type of terrain, and the underground water level (Butler et al 1986;Flowers 1975;Cantero et al 1998;Requena et al 2001;Qian et al 2007Qian et al , 2008Stavi et al 2008;Sang 2009). However, the relationship between vegetation coverage, species richness, and environmental factors has not been investigated.…”

Cyanobacterial composition and spatial distribution based on pyrosequencing data in the Gurbantunggut Desert, Northwestern China

“…With coverage of less than 30%, natural vegetation is dominated by Haloxylon ammodendron and H. persicum . The elevation is from 520–550 m . The desert has fixed sand dunes.…”

“…The evidence of field survey and remote sensing indicated that BSC distribution existed distinct variations in the Gurbantunggut Desert . Moreover, the landscapes of the Desert are diverse and the landform morphology represents apparent differentiation from east to west and north to south . The differences of BSCs distribution and landscape of desert can lead to variation of environmental factors .…”

“…Moreover, the landscapes of the Desert are diverse and the landform morphology represents apparent differentiation from east to west and north to south . The differences of BSCs distribution and landscape of desert can lead to variation of environmental factors . Though cyanobacterial composition and distribution within BSCs were previously characterized in detail morphologically and have been discussed in several reports in different arid regions.…”