干旱、寒冷的气候条件是我国北方,尤其是广大西北地区树种分布和生长的主要限制因素。在长期的自然选择过程中,不同的树种其抗旱耐寒能力明显不同,分布区广的树种,不同分布区的种群间其抗寒、抗旱性也有显著差异。所以,正确评定树种的抗旱、抗寒能力,筛选出适合我国干旱、寒冷 Drought and cold climatic conditions are the main limiting factors for the distribution and growth of tree species in the north of our country, especially in the vast northwest of China. In the long-term natural selection process, the drought resistance and cold tolerance of different tree species are obviously different. There are also significant differences in the cold-hardiness and drought resistance among the widely distributed tree species and populations in different distribution areas. Therefore, the correct assessment of tree species drought, cold ability, selected for our drought, cold