Group lightning mortality of trees in a Neotropical forest

Abstract

Gaps caused by multitree, multispecies lightning mortality have been documented for south-east Asian rainforests (Anderson 1964). The same author cites cases of multitree, though usually not multispecies, mortality due to lightning in the temperate zone. Although multitree lightning damage is more common in forests with relatively uniform canopies, such as mangrove forests, it occurs in a variety of tropical forest types, and Anderson (1964) concluded that lightning is one of the most important factors causing mortality among dominants in tropical rainforest. Apart from reports from mangrove forests in Florida (Smith et al. 1994) and Panama (W. Sousa, pers. comm.) we are unaware of any reports of multitree, multispecies mortality caused by lightning in Neotropical forests. Lightning gaps may be attributed to other causes because of the absence of the usual evidence of lightning damage, such as shattering or splitting of the bole or charring of the bark. However, Anderson (1964) states that 'this general absence of direct manifestation of lightning damage is not unusual'. Here we describe multitree, multispecies mortality in a Neotropical rainforest which local forestry workers attribute to lightning strikes. We were sceptical at first because we were unaware of the south-east Asian literature and also other experienced Neotropical forest ecologists did not know of the phenomenon (D. & D. Clark, C. Uhl, N. Higuchi, pers. comm.). However, the similarity of the gaps to those described for south-east Asia and the lack of other plausible causes leads us to conclude that such large lightning gaps are also typical of at least one Neotropical forest.