Ancient tea gardens play important role on in situ conservation of epiphytic orchids in southwest Yunnan, China

Southwest Yunnan of China is the homeland of famous Pu'er tea and preserved the largest area of ancient tea gardens in the world. The ancient tea gardens keeping a large number of shade trees have prevailed for hundreds of years persist and formed typical agroforestry systems. To assess the potential of the ancient tea gardens for in situ orchid conservation, in this study, three typical ancient tea gardens located at different elevations, JiNuo Mountain ancient tea garden (JNM, 1150 m asl.), JingMai Mountain ancient tea garden (JMM, 1345 m asl.), and LaoBanZhang ancient tea garden (LBZ, 1787 m asl.), were selected to investigate species diversity and composition, and conservation status of all orchids. Floral visitors, reproductive success, and seedling recruitment of selected epiphytic orchids were also investigated from 2019 to 2021. We identified 88 orchid species (85 epiphytic and 3 terrestrial orchids) in 33 genera in the three ancient tea gardens, including one critically endangered species (CR), four endangered species (EN) and 16 vulnerable species (VU). Although the orchid species diversity was not significantly different, the species composition varied greatly among the three ancient tea gardens. For the randomly selected 40 epiphytic orchid species, all species could set fruits naturally, and the natural fruit-sets ranged from 1.11 +/- 6.0% to 62.07 +/- 15.4% with great variations among species and years. For 60 epiphytic orchid species observed, seedling recruitment for 26 species (43.3%) were observed and confirmed. Among 42 insect visitors observed, 21 species including bees, flies and ants, were confirmed as effective pollinators to 16 epiphytic orchids. These results revealed that the ancient tea gardens maintained high species diversity of epiphytic orchids and provided pollinator services for reproductive success and suitable micro-environment for seed germination and seedling recruitment. We strongly suggested that the ancient tea gardens in the area could serve as important supplements for in situ conservation of epiphytic orchids.