نبذة مختصرة : Sixième inventaire des placettes permanentes de la Réserve (1994, 1997, 2000, 2004, 2015, 2022) ; The main lesson that can be learned from the census of permanent plots of the Caravelle reserve in January 2022, after a two-year long severe drought, is the high level of vegetation decline and dieback, in forest canopy as well as the undergrowth and herbaceous layers. Vegetation cover was dramatically reduced, because of both plant mortality and a high level of defoliation of survivors, while most plants usually keep their whole foliage in January, the end of the rain season. It was difficult to assess whether defoliated trees and shrubs, particularly those from evergreen species supposed to remain green in the dry season, were dead, dying, or simply in an exceptional transitory leafless stage to cope with the extreme drought and may recover at the next rain season. In case of survival, they will be severly weakened. A high proportion of living trees and shrubs displayed dead branches, sometimes whole top-crown death. These droughts have made vegetation density to loose most of what had been gained in the previous 30 years of positive dynamics. They led to more losses and damages than each of the two last hurricanes. The replenishment of the canopy by the growth in height and diameter of young trees dropped by 41% compared to previous censuses, with a 15% loss of total number of trees. Mean annual tree diameter growth declined by 60%, confirming an intense and long lasting stress. Unlike all previous censuses, the undergrowth did not take advantage of canopy openings, as it was also severely affected by drought, with some dominant species showing up to 50% of mortality. The upper strata (from 30 cm to 1 m) of nearly all patches of flagged vegetation along the coast was leafless, dry or dead, with many dead scattered individuals and sometimes whole rows fully dead. The follow-up of all plots during the next rain season (to check vegetation resilience or dieback aggravation) is necessary to assess real drought ...
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