DEB-9812375 Laurance and Williamson This project funded by the Small Grants for Exploratory Research program will study the 1997 El Ni o (ENSO)-related drought impacts on tree mortality in the central Amazon. In the second half of 1997 the Amazon Basin experienced a severe ENSO-driven drought, considered the third worst drought in more than 100 years. One station recorded 80 consecutive days without precipitation at a station where the annual average is only 45 days without precipitation. There is significant reason for concern about impacts of this extended drought, both in terms of effects on tree survivorship as well as disturbances following this event. Unusually high levels of tree mortality are likely under these drought conditions and already the PIs describe signs that this indeed will be the case. This project will take advantage of a 66 ha primary forest with 18 year records of tree mortality and re-census 15,000 trees in 21 ha. This work will provide significant insight into species-specific differences in drought tolerance in Amazonian forest trees. There is the possibility that this ENSO-related event will alter the structure of these forests for decades if not longer. This proposal is valuable not only because of the extreme drought experienced this year but because of the dearth of such studies in tropical rainforest habitats.
