"The increase in diversity estimates started well before the LGM [Last Glacial Maximum] and accelerated from 20 ka ago onward. The highest diversity was then reached during the Younger Dryas dry event (~12.9 to 11.7 ka ago) (25), during a phase of major ecological disturbance and not during the following early Holocene phase of forest stability at 10 to 9 ka ago."

All of this has led the study authors to conclude "that Afromontane forests of Cameroon are neither 'glacial' nor 'contemporary' refugia. Glacial climates did not lead to forest disappearance but had a major impact on the upper treeline, which shifted dramatically, revealing the sensitivity of the upper montane biomes to climate change."