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 650-4700m. 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 increment 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 1051m and 3000m 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 saprophytic orchid species in each elevation group. There were more epiphytic orchid species from 1051m to 1450m, whereas there were more groundliving orchid species between 1851m and 3450m in elevation. There were 223 orchid species between 1851-2250m, 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 2120m in elevation, and the life form equilibrium point was around 2050m.