Abstract: he net primary productivity (NPP) of subtropical evergreen broadleaved forest(SEBF) in China was calculated by means of Holdridge's life zone classification system and Chikugo model. The change of NPP of SEBF was also estimated under the global warming caused by doubled CO₂ content in the atmosphere. The results showed that the NPP value of SEBF is meanly 12.81t·hm^-2·a^-1 under present climatic condition. When the annual mean temperature increases 2℃ and the annual precipitation increases 20%, NPP may increase 2.14t·hm^-2·a^-1 ,up to 14.95t·hm^-2·a^-1 . When the annual mean temperature increases 4℃ and the annual precipitation increases 20%, NPP may increase 2.60t·hm^-2·a^-1 , up to 15.41t·hm^-2·a^-1 .

Key words: courtyard forest, air negative ion, coefficient of air ion, air quality, Jinan of Shandong.