Effects of the 1997-98 El Nino drought on rain forests of Mount Kinabalu, Borneo

We examined the effects of the 1997-98 El Nino drought oil nine rain forests of Mount Kinabalu, Borneo, at four altitudes (700, 1700, 2700 and 3 100 in) on contrasting geological substrata (ultrabasic Versus non-ultrabasic). Measurements of rainfall and atmospheric aridity indicated that the departure front normal conditions during the drought became greater with increasing altitude. During 1997-99 (drought period) compared to 1995-97 (pre-drought period), median growth rates of stern diameter of trees decreased for both smaller (4.8-10 cut) and larger (greater than or equal to 10 cm) diameter classes in the six forests (greater than or equal to 2700 m on ultrabasic substrata and 1700 in oil non-ultrabasic substrata), but For neither diameter class in the other forests. The majority of species decreased or did not change growth rates during 1997-99, whereas some did increase. Tree mortality increased during 199799, at the larger diameter class in the two lowland forests (700 in) oil both substrata, and at least at the smaller diameter class in the four upland forests ( ! 1700 in) oil non-ultrabasic substrata. In two of these upland forests, mortality was restricted to particular understorey species. Mortality did not significantly increase in the three upland forests (greater than or equal to 1700 m) on ultrabasic substrata; this suggests that the adaptation to nutrient-poor soils might have provided the resistance to drought.