Abstract: Niche breadths and overlaps of 8 dominant species of Lithocarpus xylocarpus community in Ailao mountain area were researched in the present paper, and the results indicated that the community is co -dominated by Lithocarpus xylocarpus, Castanopsis wattii, Schima noronhae, and Lithocarpus chintungensis. Their niche breadth values were 0.8732, 0.7856, 0.6742. and 0.5798. respectively. Species pairs which had more similar biological and ecological properties in the mean time possess bigger niche overlap value rel-atively. For example. " Lithocarpus xyhcarpus + Castanopsis wattii" and " Schima noronhae + Hartia sinensis". Also the importance and position of Schima noronhae in the community should not be overlooked. This proposition was deduced from the fact that it had the higher niche breadth value and showed the higher niche overlap value with most of the other tree species, L. chintungensis was in an opposite situation. It usually acted as the dominant species in some special microhabitat. We used a comparative approach and a numerical analysis to study the various calculating methods of niche breadth and overlap. It should also be noted that stability of the plant community should be an important characteristic that is co - dominated by species with relatively high niche breadth means, and niche overlap exist in most species pairs of one com-munity ought to be a common characteristic of co - dominated communities.

Key words: Lithocarpus xylocarpus community

摘要： 通过多种方法比较研究了哀牢山木果石栎（Lith ocarpus xylocarpus）群落8个优势种的生态位宽度和重叠，结果表明，该群落是以木果 石栎、腾冲栲（Castanopsis wattii）、滇木荷（Schima noronhae）和景东石栎 （Lithocarpus chintungensis）为优势种的共优群落,它们的生态位宽度值分别为0.8 732，0.7856，0.6742和0.5798。木果石栎和腾冲栲、滇木荷和舟柄茶(Hartia sinens is)等生物生态学特性更为接近的物种之间的生态位重叠值较大。滇木荷与其它树种间具 有普遍较大的生态位重叠，它在群落中占有相当重要的地位；景东石栎同别的树种间生态位 重叠值较小，形成了局部小生境地段的优势种。文章指出，由几个生态位宽度都较大的种类 组成共优群落是植物群落稳定性的重要标志之一，群落中物种之间存在较为广泛的生态位重 叠是共优群落的一个普遍特征。

关键词: 木果石栎群落, 生态位宽度, 生态位重叠, 竞争, 稳定性, 哀牢 山