Keywords Drought stress;Droughty tolerance;Ecosystem;Hunshandak Sandland;Natural force;Photosynthesis;Sparse-elm grassland;Vegetation;Ulmus pumila;Water potential;Water use efficiency;

• 浑善达克沙地;榆树;榆树疏林草地;生态系统;植被;自然力;干旱;光合作用;水势;水分利用效率;