E02: This episode profiles the rich biodiversity of south-western Yunnan province. Forming the eastern boundary of the Himalaya, the Hengduan Mountains have buckled into a series of parallel ridges running north-south. The Nujiang River is one of a succession of deep gorges that carve their way through the mountains. In summer, monsoon rainclouds from the Indian Ocean are funnelled up the valleys, creating a unique climate in which species from the tropics can flourish at a more northerly latitude. Yunnanâ€™s 18,000 plant species, of which 3,000 are found nowhere else, attracted Western botanists and explorers such as Joseph Rock. In the snowbound forests surrounding the pilgrimage site of Kawakarpo (6740m), rare Yunnan snub-nosed monkeys are filmed feeding on lichen. In the Gaoligong Mountains, tropical and alpine plants grow side by side. Birdlife filmed here includes sunbirds feeding on epiphytes and the courtship display of a Temminck's Tragopan. The fruiting trees attract bear macaques and black giant squirrels, whilst Chinaâ€™s 250 remaining wild Asian elephants forage below. A Lesser Bamboo Bat colony is filmed at their roost inside a single stem; each bat is the size of a bumblebee. A giant elephant yam flower is pollinated by carrion beetles at night. Black crested gibbons are filmed in the forests of Wuliangshan. The people of Yunnan include the Dai, Hani and Jino tribes, each of whom regard the forests as sacred and harvest them sustainably, but modern times are bringing new threats such as rubber plantations and tourism.