Restoration of tropical seasonal evergreen forest depends on improving soil fertility and species diversity. Research has shown that soil fertility can be improved gradually after vegetation recovery. In this paper, the development of species diversity and its effect on the restoration process in tropical China have been studied based on the survey of a long-term site. The main results are as follows. (1) After vegetation recovers in a degraded ecosystem, species diversity expands quickly. Species structure moves toward that of the climax structure in spite of different initial species combination and habitat. Of 72 tree species existing in a 1400 m(2) site of man-made mixed forest, 47 tree species are natural colonizing species which are all common species native to this region of China. These results show that species diversity can be restored in a degraded tropical seasonal evergreen forest ecosystem. (2) The restored forest develops toward the zonal vegetation type. The speed at which it develops seems uneven. By measuring the P-diversity index of restored forests established at different times, it can be shown that the community habitat differences between subsequent years become increasingly larger. Although this pattern is affected by many tangled factors, forest age is probably the most important. This might suggest that the restoration of species diversity occurs faster in the early and middle stages of the process of vegetation development. (3) The soil fertility, plant species diversity and the diversity of mammals, birds and microbes appear to mutually facilitate one another. (C) 1997 Elsevier Science B.V.
