| To find out the undergrowth plants diversity in western Shanxi Province forest region of the Loess Plateau,based on the data of 14 quadrats’vegetation, richness index, diversity index, Simpson index, evenness index were adopted
to study the species diversities of major communities. The results showed that there were 102 kinds of vascular plants,
including 73 kinds of herbaccous, 31 kinds of shrub and 12 kinds of arbors. The species diversities increased in the order
of the herbaceous layers，the shrub layers and the arbor layers in different forest communities. In the shrub layer, the
species diversity appeared higher than that in herbaccous layer, like Populus davidiana secondary forest and Quercus
liaotungensi secondary forest. In different communities, the species diversities in shrub layers secondary forest were higher than plantations in P. davidiana secondary forest and Robinia pseudoacacia plantations. In herbaceous layers, plantations was higher than secondary forest in Robinia pseudoacacia +Platycladus orientalis mixed forest and Pinus tabulaeformi planation. Robinia pseudoacacia platationg and Populus davidiana +Quercus liaotungensi secondary forest was lower.Richness index was different in shrub layers and herbaceous layer, in shrub layers, it appeared the order of secondary forest, mixed forest and purebred forests, and in herbaceous layer, it appeared the order of purebred forests, mixed forest and secondary forest. Diversity analysis showed that mixed forest had more similarity to secondary forest than purebred forests. The result indicated that the afforestation in low density and the afforestation of mixed forests with multiple tree species could increase the community diversity. The vegetation recovery could be promoted through creation of forest gap and mixed configuration of species. |
