Abstract: Due to a long history of hunting and habitat deterioration,many populations of the critically endangered western black crested gibbon (Nomascus concolor)are distributed in small scattered areas． We established 55 sampling quadrats and conducted a floristic investigation in an isolated and disturbed forest occupied by a small group at Bajiaohe, southern Yunnan, China． A total of 85 species in 57 genera and 28 families were recorded in the forest, which was dominated by Fagaceae, Lauraceae and Staphyleaceae．The floristic composition and structure differed significantly between areas in different forest fragments and varied with topography．We studied diet and home range use of the group over two years using a scan sampling method．The gibbons at Bajiaohe relied on some dominant tree species such as Litsea subcoriacea and Turpinia pomifera as food resources．They visited more liana fruits in secondary vegetation when tree fruits were less available, but did not consume more leaves and buds．It is noteworthy that the gibbons did not feed on any figs．This may be explained by the low availability of fig plants caused by human disturbance． The tree community structure did not have an effect on habitat use by the gibbons in the primary forest, but they showed significant preferences in different fragments．There was remarkable variation in the floristic characteristics between the four habitat sites used by the western black crested gibbon in Bajiaohe, Dazhaizi, Pinghe and Tea-horse Ancient Road．The gibbons’behavioral adaptation or flexibility in relation to this environmental variation requires more detailed studies at a larger temporal and spatial scale．

Key words: Ecobehavioral adaptation, Floristic composition and structure, Habitat fragmentation, Nomascus concolor

摘要： 由于长期的捕猎及森林破坏，许多西黑冠长臂猿群体生活于零散的小型生境片段中。在云南南部芭蕉河地区，利用55个样方测量了西黑冠长臂猿一个隔离小种群栖息地植被，共记录乔木28科57属85种，其中壳斗科、樟科及省沽油科占优势地位，植被组成与结构在不同的森林片段、地形及干扰程度区域中差异显著。利用瞬时扫描法在两个年周期中的系统观察发现，与连续森林中的群体相比，芭蕉河长臂猿更加依赖对桂北木姜子、大果山香圆等优势乔木树种的取食，在乔木果实缺乏的季节，其并未取食更多叶类，而是进入次生植被搜寻藤本果实。可能受人为干扰及植被结构的影响，长臂猿未取食无花果类植物。原始林中植被结构并未对长臂猿生境利用造成明显影响，但其在不同森林片段间表现出显著的选择性。通过对芭蕉河、大寨子、平河及新平茶马古道四地的比较发现，西黑冠长臂猿栖息地植被特征存在较大的地区差异，其生态与行为可能因此表现出较强的适应性，但这需要更大时空尺度的研究予以验证。

关键词: 西黑冠长臂猿, 栖息地片断化, 植被组成与结构, 生态行为适应