ObjectiveThis study aims to provide scientific basis for the restoration and reconstruction of vegetation in the Loess Plateau by studying the characteristics of plant diversity and its correlations with the environmental factors in different forestland.

MethodTaking 3 kinds of artificial forests (Pinus tabuliformis forest, Robinia pseudoacacia forest, mixed forest of Pinus tabuliformis and Robinia pseudoacacia)) and 2 kinds of natural secondary forests (Populus davidiana, Quercus liaotungensis) in Caijiachuan Basin of Jixian County, Shanxi Province of northern China as research objects, we carried out vegetation investigation by standard sample land survey method.

ResultThe results showed that there were 52 species of undergrowth plant, including 17 shrubs and 35 herbs, and the species composition and distribution of different forest types were quite different. The number of shrub species in natural secondary forest was more than artificial forest, but the number of herb species was less than artificial forest. There was no significant difference in the evenness index of shrubs among the five forest types. Species richness index and diversity index both showed natural secondary forest > artificial forest, while the species richness index, evenness index and diversity index of the herb layer all showed as artificial forest > natural secondary forest. Environmental factors had a significant impact on plant diversity, especially canopy density, soil water content and capillary porosity.

ConclusionThe characteristics of plant diversity varied significantly in different forest types. Considering the composition and diversity of shrubs and herbs, the mixed afforestation of P. tabuliformis and R. pseudoacacia was better than pure afforestation, so the area of mixed forest should be expanded reasonably. In addition, canopy density was the main environmental factors affecting plant diversity. Therefore, the appropriate intervening forest could improve the diversity of undergrowth plants.