<p>This monograph is divided into three parts. The first part explores the impact of drought on root morphology. It is found that the root systems of introduced trees (such as poplar, elm, and birch) show a trend of shallow rooting, the horizontal root system expands significantly (up to 2-3 times the crown diameter), and the vertical root system depth is limited by the soil structure, and most are concentrated in the 0-50 cm soil layer. Studies point out that the horizontal distribution of root systems is an adaptive strategy to shallow soil moisture. For example, the roots of Robinia pseudoacacia and Elaeagnus angustifolia expand their water absorption range through lateral extension during drought periods. The second part studied the relationship between root physiological characteristics and drought resistance, indicating that drought-resistant tree species (such as Caragana and Hippophae rhamnoides) have higher osmotic pressure in root cells and smaller xylem vessel diameters, which can reduce water loss. Experimental data showed that root respiration rate decreased by 30%-50% under drought stress, but soluble sugar and proline content increased, enhancing cell water-retaining ability. In addition, mycorrhizal symbiosis significantly improves the absorption efficiency of phosphorus and water by roots. The third part evaluates the application potential of introduced tree species and proposes screening criteria based on root characteristics: priority should be given to species with developed horizontal root systems and high root-to-crown ratios (such as Populus simonii, White Ulmus chinensis), and recommends promoting lateral root development through root cutting at seedling stage. The study also pointed out that the mixed planting model can optimize the spatial distribution of root systems, improve the overall drought resistance of the community, and provide a theoretical basis for vegetation reconstruction in arid areas. </p>