Abstract: To understand the degradation mechanism of Père David’s deer habitat, an investigation was made on the plant community characteristics in Père David’s Deer Natural Reserve in Dafeng of Jiangsu Province. In the Reserve, the community similarity index of the grassland inside and outside the fence was low. The aboveground biomass, species number, richness index, Shannon index, and evenness index of the plant community inside the fence were all lower than those outside the fence, whereas the ecological dominance index of the plant community was in adverse. The further the distance between grassland communities, the lower the plant community similarity index was. Inside the fence, the species dominance of Pennisetum alopecuroides was absolutely dominant. With the increasing distance from the activity center of Père David’s deer, the plant community evenness index increased, and the percentage of P. alopecuroides aboveground biomass in total plant community as well as the population characteristic values of P. alopecuroides declined. It was considered that the fire for killing Haemaphysalis longicornis could be one of the major reasons causing the habitat degradation. The results could serve as the theoretical references for ecological restoration of Père David’s deer habitat.

Key words: Photosynthesis, Elevated CO₂ concentration, Photosynthetic characteristics