Fog and People in Xishuangbanna, Yunnan Province, China

The Xishuangbanna Dai Autonomous Prefecture, located in the extreme south of Yunnan Province (China), comprises 49 basins and is known as a region that experiences frequent foggy days. Different ethnic groups have long coexisted in this region, separated from one another by this fog. The Dai people inhabit the basin floors, where they have traditionally maintained trees, which are the water source for the fog, in order to use the latent heat of the fog droplets to protect their crops from cold nighttime temperatures. Meanwhile, the mountain ethnic minorities inhabit the nighttime thermal belt that exists on the slopes above the fog layer and also receives early morning sunlight, where they have traditionally practiced a form of swidden agriculture that promotes forest regeneration. The peoples in this region have thus been able to maintain stable geoecosystems over entire basin areas. Since the 1960s, however, large-scale development driven by national policy has started to erode the geoecosystems of this region.