Abstract: The niche breadths and overlaps of 14 main tree populations and 22 main shrub populations in deciduous broad leaved forest in Baotianman, Henan Province were measured using the formulas described by Levins, Hurlbert and Pianka, and the relationships among niche breadth, niche overlap and interspecific association were discussed in this paper.The results show that the niche breadths of main dominant species were greater. The Levins and Hurlbert's niche breadths of Quercus aliena var. acuteserrata and Toxicodendron verniciflnum,the main dominant species in tree layer, were 18.527, 7.488 and 0.889, 0.680 respectively,and those of Celastrus gemmatus, Vitis amurensis and Lespedeza bicolor, the main dominant species in shrub layer, were 18.964, 14.479, 13.251 and 0.908, 0.799, 0.785 respectively. The niche overlaps among the species with the same or similar environment requirements were great, while those between the species with broad niche breadth and other species were much greater. The more intense the positive association was, the larger the value of niche overlap was, and the more intense the negative association was, the smaller the value of niche overlap was.

Key words: Deciduous broad leaved forest, Population, Niche breadth, Niche overlap, Baotianman, tea cultivation, specialization, location, geographically weighted regression, Anxi County