Niche Characteristics of Dominant Populations in Pinus kwangtungensis Community in Hainan

Key words: 
• Pinus kwangtungensis /
• niche /
• Yingge Mountains /
• Jiaxi Mountains /
• Hainan

Abstract: Pinus kwangtungensis is a special species of conifers in China,mainly distributed from the north tropics to the north pan-tropics. As P. kwangtungensis was distributed in the southernmost area in China it is of a great scientific value and practical significance to analyze the coexistence mechanism of community species,the community structure and stability of P. kwangtungensis forest. Four sample plots or quadrats were established:three from the Yingge Mountains and one from the Jiaxi Mountains,with a total land area of 144 00 square meters,6 060 m each plot,to make a comparative study in dominant population niche and inter-specific associations. The results showed that the niche breadth of P. kwangtungensis population in the four plots was in the order of Plot 4（ 2. 101 4） ＞ Plot 1（ 1. 601 6） ＞ Plot 2（ 1. 444 1） ＞ Plot 3（ 1. 170 1）,indicating P. kwangtungensis in Plot 4 had the highest adaptation and competition but the lowest in Plot 3. The niche overlap of P. kwangtungensis and other dominant populations in the four plots was similar to the niche breadth in the order of Plot 4 ＞Plot 1 ＞ Plot 2 ＞ Plot 3. In Plot 4 the P. kwangtungensis population had the highest niche overlap with other dominant populations and hence competed and excluded most seriously with other dominant populations. The pairs of the species with high niche overlap in each plot contributed 85%,84%,71% and 84% to the total pairs of the species,and the species in the community had a very high niche overlap in their use of the resource and living space. The results showed that the P. kwangtungensis community had a high interspecific similarity in requirements of the species for habitat and resource in Hainan,and that the species in the community did not have a high niche differentiation and had a high competition in use of the resources,indicating that this community was still an instable and transitional community from the needle and broad-leaved mixed forest to the evergreen broad-leaved forest.