黄土高原气候干旱:雨量稀少,降雨分布主要集中在7、8、9三个月,占全年降雨量60—70%,干旱发生频率高。年温差及日温差大,夏季极端气温30—40℃,而地表温度有时可高达60—70℃。这种气候特点对飞播造林种子的发芽出苗影响很大。因为飞播造林是模拟天然更新的机械化造林方法,是将种子直接 The arid climate of the Loess Plateau: rainfall is scarce, rainfall distribution is mainly concentrated in 7,8,9 three months, accounting for 60-70% of the annual rainfall, drought frequency. Annual temperature difference and daily temperature difference, the summer extreme temperature 30-40 ℃, and sometimes the surface temperature can be as high as 60-70 ℃. This climate has a great influence on the germination and emergence of aerial seeding and afforestation seeds. Because aerial seeding is a mechanistic afforestation method that simulates natural regeneration, the seeds are directed directly