Abstract: Based on the 1961-2009 daily mean and minimum temperature data from 62 meteorological stations in the fluecured tobacco planting areas of Yunnan Province, Southwest China, and by using lowtemperature indicators and weighted index, the chilling damage index model for the flue-cured tobacco was constructed, and the variation characteristics of the chilling damage index were analyzed by the methods of linear tendency and MannKendall test. In 1961-2009, the yearly variation of the provincial average chilling damage index of the flue-cured tobacco in spring, summer, and autumn presently a decreasing trend, being most obviously in spring, and with a similarity in summer and autumn. The provincial average chilling damage index of the flue-cured tobacco in spring and summer reached the maximum in the 1960s and 1970s and the minimum in 2001-2009, while that in autumn reached the maximum in the 1960s and the minimum in the 1970s. Much more stations showed a decreasing trend in the chilling damage index, and the latter changed significantly in spring and summer but less in autumn. The Mann-Kendall test showed that the yearly variation of the provincial average chilling damage index in spring was significant, with an abrupt change in 1997, but the yearly variation in summer and early autumn was not significant. Thirty percent of the stations in the Province showed a significant abrupt change in spring, and less than 10% of the stations showed the abrupt change in summer and autumn. Most of the abrupt change in each station mainly appeared in the late 1980s and 1990s.

Key words: Taxus chinensis var. mairei, species diversity, community structure, competition., regeneration