The effects of phenological change on Populus euphratica under the background of climate change

Although phenology is a key indicator of climate change, the effects of phenological change under the background of climate change remain unexplored in arid and semi-arid region. We studied the phenological change of Populus euphratica during 1960–2019, and investigated the relationships between phenological change and climate change. The results showed that the annual average temperature in the Lower reaches of Heihe River was increased significantly over the past 58years, which directly led to the flower bud opened early, and delayed the time when the leaves turn yellow of Populus euphratica. The growth season of Populus euphratica was significantly prolonged after 1990, and the mean growth season length were 230, 236, 245 days in 1960–1969,1990–1999,2010–2019, respectively. Temperature is the major environmental factor affecting phenological change, and the length of growing season was prolonged with the increase of annual average temperature and accumulated temperature. Phenological changes have an important effect on plant growth. Our study showed that the frost days of Populus euphratica increasing from 1990 to 2019, and the frost days was increased with the growth season length. The accumulated frost days were 19, 21, 23 days in 1990–1999, 2000–2009, 2009–2019. The results also indicated that phenological changes also affect socioeconomic, especially the delay of leaf yellow period maybe has an important impact on tourism due to the best viewing period is postponed. This study of phenological change law and its relationships with climate changes could guide the government formulates tourism policies and help tourists to arrange best viewing time.