Light and water have only been discussed in the leaf phenology studies of low latitude tropics, though soil nutrients were also included as potential contributive factors. We investigated the relationship between these environmental factors and leaf phenology in the tropical montane forests of Mount Kinabalu, Borneo. Three montane forests of different vegetation were compared during the 1998 El Niño drought in order to differentiate the effect of each environmental factor. As a result, the relationship between soil pulsed nutrient release and leaf flushing was denoted in the forests with an affluent water supply, while water stress suppressed leaf flushing in all vegetation. However, the contribution of light could not be determined. This study is the first to indicate the contribution of soil nutrients to leaf phenology in the tropics.