Abstract: Based on the phenological phase change of Populus tomentosa in 4 observation stations in Qinghai during 1987-2003,its response to climate change were analyzed.The result showed that the green leaf growth period prolonged in resent 10 years.The response of the phenological phase change to temperature change was very sensitive.Due to the mean air temperature increased 1℃ from September to April next year,the mean leaf bud opening phase was ahead of 5 days,the leaf unfold phase was ahead 3 days,the florescence starting phase was ahead 4 days.Due to the mean air temperature increased 1℃ from September to June next year,the seed maturation phase was ahead about 3 days.When the mean air temperature increased 1℃ from September to August next year,the whole leaf turn color phase delayed 4-5 days,and the mean interval days was prolonged 12 days from leaf bud open to whole leaf turned color in autumn.There was not apparent response to precipitation and sunlight.

Key words: Populus tomentosa, Populus tomentosa, Phenological phase, Climate change, Response