Phenological Changes of Ligneous Plants in Xi'an Botanic Garden in Last 15 Years

Phenological data of 20 ligneous plants in Xi'an botanic garden from 1988 to 2002 was analyzed.The results showed that the spring phenological phenomena of all observed 20 ligneous plants had been earlier since 1988,while the autumn phenological phenomena of most observed 20 ligneous plants had been delayed.The response of the spring phenological phenomenon to the climate change was more obvious than that of autumn phenological phenomenon.As to majority plants,the change extent of reproduction growing phenological changes was greater than that of nutrition growing phenological changes.The results of this article are of great value to evaluate phenology and the response of different phenological index to climate changes on climate changes.