Abstract:Dominant species and natural rattan populations in secondary lowland rain forest of Ganshilin Natural Reserve Area in Hainan Island were as test materials. According to contrastively analyzing important values of rattan and dominant species in the community, we conductedto identify utilization and competition relationships of rattan interspecies with dominant species at layers,niche breadth, niche proportional similarity and niche overlap to explore the mechanism of rattan and dominant species at forest layer, so as to provide some theoretical references for protection to rattan resource. The results were presented as follows:(1)Vatica mangachapoi and Hopea reticulata were constructive species, 5 kinds of rattan hadrelatively upper IV in community,but there was quite a difference.Calamus rhabdocladus (Cr) had maximum IV, was 0.286. Plectocomia microstachys(Pm)had the minimum, IV equal to 0.053, sorting as follow: Cr> Cf> Dj> Ct>Pm. (2) Rattan had greater niche breadth, in which the greatest one was Cr, Biand Bawere 2.900 and 0.612, respectively, obviously greater than the species at herb layer and had little difference with other layers. (3)The results of niche proportional similarity were indicated that the lower similarity was showed between rattan and dominant species in layers, only excepted for Dj and Callerya nitida, basically the species at layers of the largest similarity with rattan palms were same, which were Alpinia oxyphylla, Millettia reticulata, V. mangachapoi and H. reticulate. The similarity of Cr had the highest ratio with other rattan, on the contrary, Pm hadthe lowest ratio. (4) Lik and Lki between rattan and dominant species in layers were generally lower. All of those were less than 0.1, and niche breadth and overlap were not positively correlated. The value of overlap between 0-0.023 accounted for 63.5%, 36.0% of quantity were focused on 0.023-0.046, only 0.5% left for the rest. The study indicates that rattans in the region have relatively higher resource utilization capacity among the community species. However, great interspecies discrepancies and niche differentiations are showed among rattan interspecies and with dominant species, tending to resource sharing.