Background There are both mountainous and coastal landforms in the Yantian district of Shenzhen city. Studying on the niche characteristics of dominant species in tree layer and shrub layer of the forest community in Yantian district has important research value for the study of soil erosion in the transition from mountain to coastal landforms, and provides a corresponding scientific reference for local vegetation allocation and soil and water conservation projects and theoretical support for forest resource management and operation.

Methods To explore the niche characteristics of the dominant species in the forest community in Yantian district of Shenzhen city, 6 large quadrats representing regional population characteristics were selected for investigation in August 2018. Data on tree number, tree height, DBH, crown diameter and height under the branches of tree layer species, as well as data on tree number, base diameter, crown diameter and height of the shrub layer species were investigated. Niche breadth and niche overlap were used to discuss the niches of the dominant species in the tree and shrub layers of the community on the basis of field plot surveys.

Results 1) The Levins (B_L) and Shannon (B_S) niche breadth indexes for Psychotria asiatica in the shrub layer were 2.77 and 0.10, ranking 5 and 14, respectively, but the importance value was 18.02. 2) In the tree layer, the niche width of Ficus variolosa Lindl. ex Benth. was the largest, and the B_L and B_S were 5.08 and 1.70, respectively and, the niche width of Rhododendron henryi Hance was the smallest. 3) In the shrub layer, the niche width of Diplospora dubia (Lindl.) was the largest, and the B_L and B_S were 4.67 and 1.26, respectively, and the niche widths of Enkianthus quinqueflorus Lour. and Symplocos stellaris Brand was the smallest. The average niche overlaps of the tree layer and shrub layer were 0.40 and 0.32, respectively, and the overlap values of most species pairs were below 0.5. In addition, the niche breadths of Schima superba Gardn. et Champ. and Acacia confusa Merr. in the tree layer were relatively small, but the niche overlap reached 0.9.

Conculsions The Levins and Shannon niche breadth index values ranked in the same order but were different than the important values. The niche overlap of species pairs with larger niche breadths was larger, but they were not completely consistent. The competition of the dominant species in the community of the study area was not intense and the community was relatively stable.