Abstract:

The dead Halogeton arachnoideus can still remain upright and play a role in sand fixation， making it a hotspot in the study of wind prevention and sand fixation in arid and semi-arid regions. On the basis of field investigation and grain size experiment， this paper analyzes the morphological and sedimentary characteristics of the shadow dunes of H. arachnoideus， a dead vegetation in the southern margin of Qaidam Basin， by using relevant statistical methods. The results show that： （1） The correlation between the parameters of shadow dune is significant （P<0.01）， in which the vertical and horizontal scales of dune have good correlation， and the fitting relationship between the length and width of dune （R²=0.6） is better than other parameters. （2） There is a significant positive correlation （0.8≥r>0.5， except dredge degree） between the parameters of dead H. arachnoideus and the shape of shadow dune. The contribution of vegetation length and width to the extension of dune length is gradually decreasing， while the contribution of vegetation height to it is increasing. （3） The canopy area， length and dredging degree of H. arachnoideus were significantly correlated with the volume of shadow dunes （P<0.01）， and the fitting relationship between canopy area and volume was good （R²=0.8）， which jointly affected the sand interception capacity of H. arachnoideus. （4） The main grain size fractions of the sediment are very fine sand and fine sand， Under the influence of plants， the wind force gradually decreases， and the grain size of sediment along the wind direction gradually becomes thicker.

Key words: shadow dunes, Halogeton arachnoideus, morphological character, grain size characteristics, Qaidam Basin