ABSTRACT
Introduction Global change and its direct result, change in the living environment of humans, is gaining more and more attention from international scientific circles and governments of many countries (Zhang, 1994; Ye and Chen, 1992; Fu and Yan, 1996; Peng 1997; Peng and Ren, 1998; Koch, 1996). Research results from many scientists in the world show that global change exerts an obvious influence on the structure and functional processes of agricultural ecosystems (including forest, grassland and farmland ecosystem) (Liu 1993; Feng et al. 1999; Zhou et al. 1997; Wang 1965; Xu et al. 1997). In addition, the elevated C 02 concentration itself affects the * Address for correspondence : Hai Ren, South China Institute of Botany, Chinese Academy
primary producer-vegetation-in the ecosystem. The "greenhouse effect" resulting from elevated C02 concentration will also affect the existing energy regional differentiation, and cause change in water, heat, and other ecological factors of the biotic zone inside the biosphere (Melillo et al., 1993; Zhang, 1993; Martin, 1990; Li and Wang, 1997; Lorius et al., 1990; Deng and Yu, 1993). The energy flow of the ecosystem, however, will also react to this water-heat change. Change in the process and intensity of the material cycle, namely the biogeochemical cycle, in the ecosystem will also occur (Parton et al., 1993; Neilson, 1995; Peng and Ren, 1996).
