Plant diversity and dynamics in industrial plantations of eucalyptus

The species richness, evenness and species diversity of plants in industrial plantations of eucalyptus were studied during 6 years from 1998 to 2003, using the methods of "time specific" and "fixed position monitoring". The main results are as follows: 1) Seventy-eight species of plants appeared in the first generation stand and 39 species in the second from 1998 to 2003. The species number in the second generation stand was 50% lower than that of the first. The species richness, Shannon-Wiener index and Simpson index of the second generation stand decreased by 39.39%, 17.76% and 5.45% compared with those of the first. 2) The species richness of the industrial plantations of eucalyptus showed a "S-type" change from 1998 to 2003, and Shannon-Wiener index and Simpson index both increased with the increase of stand age, but the early increase speed was faster than the later one. The continuous cropping and short-term management will reduce the diversity because the species recovery cannot reach the primary diversity level in a management period. 3) The species richness and species diversity index of shrub layer are obviously higher than those of herb layer. But continuous cropping has effects on reducing species richness and species diversity index of shrub layer and improving those of herb layer.