滇西北兰科植物海拔分布格局

根据实际调查和整理相关文献资料，确定滇西北兰科植物409种，其分布的海拔范围为650～4700m；并按400m划分海拔段，共9个梯度，分析其垂直分布格局。结果表明：滇西北兰科植物的垂直分布格局呈“中间膨胀型”或“单峰型”，随着海拔升高，各海拔段兰科植物的数量依次为92、167、194、223、192、159、129、58、32种，其中1051—3000m海拔范围的物种多样性较高；相邻海拔段兰科植物种类相似性系数较高，海拔段相隔越远，相似性系数越小；生活型以地生兰为主，1051～1450m海拔段附生兰种类较为丰富，1851～3450m海拔段地生兰种类较为丰富，各海拔段腐生兰种类较少；1851—2250m海拔段区系成分最多，物种数为223种，占该区域兰科植物总数的54．52％；该区域的区系平衡点在海拔2115m左右，生活型平衡点在海拔2050m左右。

Altitudinal Distribution Pattern of Orchid Plants in Northwest of Yunnan Province

According to field survey and related literature review, 409 species from Orchidaceae family were identified in the northwest of Yunnan Province. The analysis on the vertical distribution pattern showed that these wild orchid plants were distributed between 650 -4 700 m. 9 altitudinal gradient groups were divided if each group covered 400 m elevation difference. It was revealed that the vertical distribution pattern of these wild orchid species in the northwest of Yunnan represented as ＇ intermediate expandable＇ or ＇ single peak＇ types, along with the incre- ment of elevation, the species number of wild orchid plants in each elevation group was 92, 167, 194, 223, 192, 159, 129, 58 and 32 species individually. The higher species diversity appeared between 1 051 m and 3 000 m in elevation. There was a higher similarity coefficient of orchid species between the adjacent elevation groups. The further in distance, the less was species similarity coefficient between the elevation groups. There were less sapro- phytic orchid species in each elevation group. There were more epiphytic orchid species from 1 051 m to 1 450 m, whereas there were more ground-living orchid species between 1 851 m and 3 450 m in elevation. There were 223 orchid species between 1 851 -2 250 m, accounting for 54. 52% of the total orchid plant species in the area with the most abundant flora component. The flora equilibrium point of this area was about at 2 120 m in elevation, and the life form equilibrium point was around 2 050 m.