Toasted Forests - Evergreen Rain Forests of Tropical Asia under Drought Stress

This paper has been written to make an enormous threat known to the public. We all know about the forest fires that raged in Indonesia and parts of Malaysia in 1997, and about the noxious haze covering the whole region, but only a few experts are aware of the threat of extinction of the last rain forest areas in Southeast Asia. As this paper will show, droughts have always been a part of these ecosystems, which normally receive plenty of rain. Mild droughts can be regarded as slight or medium disturbances, which can even have a stimulating effect according to the Intermediate Disturbance Hypothesis. However, severe droughts and fires have a destructive effect, which will only be overcome in successional stages. Logging and forest fragmentation reduce the ability of forests to overcome severe droughts. Forest fires rage in selectively logged forests, whereas they are extremely rare in undisturbed rain forests. Forest regeneration in fragmented forests is disturbed, so that we have to expect a total degradation of even effectively protected forest areas. Due to drought and fire, the remnant rain forest areas are being roasted like slices of toast . New research is also revealing that rain forests under drought stress consume more oxygen than they produce. The “green lung” and carbon sink are thus out of function. Furthermore, severe ENSO-(El Niño/Southern Oscillation)-droughts have been increasing in recent years. The consequences both for development of the region and for the whole atmosphere are imminent. Forest fires during ENSO droughts have caused extensive damage to forests and plantations, and noxious haze clouds in the whole region. Awareness about ENSO and droughts exists and is growing within the local population. Strict regulations, drought and fire alerts, and law enforcement can reduce at least the effects of drought. A logging ban, also including selective logging, may have to be considered. While this paper covers the whole of tropical Asia, it focuses on Sumatra, Borneo and the Malay Peninsula, which are the main evergreen rain forest areas. Other areas in the region have either seasonal vegetation, which is more drought adapted, or only small pockets of evergreen rain forest depending on local rain exposure – or the lowland forests ha ve disappeared. The paper concentrates on Western Indonesia, Malaysia and the very south of Thailand