Researches on the relationships between forests and″occult precip itation″(dew and fog precipitation)in foreign countries,focused on the forma tion mechanisms of dew and fog,forest canopy interception from dew and fog,in fluence of dew and fog on the distribution of species and the dynamics of vegeta tion,and its ecological effects were briefly introduced with the aim of promoti ng the studies in this field in China.According to the re ports,the dew and fo g water is one of the most important environmental factors determining the plan ts growth and dis tribution,and an important input for water balance and nutr ients cycling of the forest in cloud or fog-dominated montane regions,and its ecological effects take on many aspects.So it is essential to make further rese arch in this field and the future of ecological requires regarding occult precip i-tation should be directed towards quantify ing its hydrologic as well as its chemical significance to fog and cloud dominated ecosystems.Among the study met hods,the Dawson's work that ap-plied stable tools,using hydrogen and oxygen i sotopic 'signatures' and an iso topic mixing model that made it possible to dist inguish the plants' proportional use of deep-ground versus above-ground(i.e .precipitation and fog)water,is the best way and can be used in further resea rch.