When the El Niño drought ended in a remote Papua New Guinea rainforest, the trees did not immediately recover. Many kept dying. That is one of the findings of a recent study of more than 21,000 trees in the Wanang Forest Dynamics Plot, a 50-hectare (124-acre) research site in northern Papua New Guinea. Researchers measured tree mortality before, during and two years after the catastrophic 2015-17 El Niño drought and found that mortality was significantly higher after the drought than before or during it. “It was after the drought, the post-drought period, that you could actually see those trees dying,” said Hayden Wagia, the study’s lead author and a faculty botanist at the Papua New Guinea University of Technology’s School of Forestry. The findings suggest the effects of drought can linger long after rainfall returns. Trees that survive a severe dry period may still be weakened enough to die later, although the researchers say their study cannot determine exactly what caused the delayed deaths. The 2015-17 drought brought a substantial reduction in rainfall to the Wanang forest. According to the study, only 5.2% of the area’s total precipitation fell during the dry season during the drought, compared with 13.1% before it and 9.6% afterward. One of the study’s most striking findings was how differently trees responded depending on where they grew. Valley trees experienced relatively high mortality before and during the drought but recovered quickly afterward. Ridge trees showed the opposite pattern, with mortality increasing after the drought and remaining…This article was originally published on Mongabay

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