Niche characteristics of the primary understory populations of a Picea asperata plantation in the subalpine region of Gansu Province

Based on the data from 110 plots obtained from field surveys, and using the Levins and Shannon-Wiener niche breadth index and Levins niche overlapping index, a quantitative analysis was conducted on the niche characteristics of 30 species, including 15 shrub species and 15 herb species in the understory populations of a spruce plantation in the subalpine region of Gansu Province. In the shrub layer, Rubus pungens, Sinarundinaria nitida and R. amabilis had a greater niche breadth than other species. In herb layer, Fragaria orientalis, Dactylis glomerata, and Cardamine tangutorum had greater niche breadths. These species were highly adaptable, had broad habitats, and tended to be generalist species. The populations with greater niche breadth exhibited smaller niche overlap, whereas those with smaller niche breadth exhibited larger niche overlap. Niche breadth and niche overlap did not have a positive direct liner relationship. In conclusion, niche overlap of the primary understory populations in a spruce plantation was relatively low, and interspecific competition was not intense. Betula albo-sinensis and Geranium wilfordii were more aggressive than other species based on their eco-response, and they will develop as the dominant species of main understory population in the spruce plantation in the future.