Study On The Niche Of Dominant Population In Jubaoshan Forest Park In Nanjing

Jubaoshan Forest Park is one of the main constructions of the country park in Nanjing, which is also the valuable ecological resource of the eastern Nanjing junction. Based on the 100 ×100m grids in Jubaoshan Forest Park, we chose 76 typical sections from each grid to layout the samples. According to the sample survey, the basic characteristics, internal structure and distribution of the populations in the forest park were analyzed. 13 populations from the arbor layer, 15 from the shrub layer and 11 from the herbal layer were chosen to research their niche characteristics, thus providing theoretical basis for inter-specific allocation and population improvement of plant communities, as well as the planning and construction of the whole country park. The results are as follows:(1) The main vegetation types of forest community in the park are the evergreen deciduous broad-leaved mixed forest, the deciduous broad-leaved forest and the coniferous and broadleaved mixed forest. The community composition of the park is rich in plant species, in which angiosperms accounted for advantage. Community floras were mainly the north temperate and pantropic distribution, which is consistent with the subtropical to temperate transition zone, Nanjing. The main components of the forest were regional monotypic genera and oligospermous genus, which suggested the complexity and diversity of the community composition in climate ecotone.(2) The results of two niche breadth indexes were basically the same. In the arbor layer, Celtis sinensis has the largest niche breadth, which along with Quercus glandulifera var. brevipetiolata and Pistacia chinensis was the main edificators in the community. In the shrub layer, the niche breadths of Symplocos paniculata Rubus hirsutus and Broussonetia papyrifera were considerably large because they were suitable for the underwood environment and played important roles in this layer. In the herbal layer, Ophiopogon japonicas and Trachelospermum jasminoides had larger niche breadths.(3) The niche overlap among the dominant populations was generally not high, the herbal layer is slightly higher, which suggested that niche differentiation among populations was obvious and the competition is not fierce. In conclusion, the community was in a relatively stable stage.(4) The niche similarities among populations with broader niche breadths were relatively high. There was a certain correlation between niche overlap and niche similarity.