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Stability of a Neotropical microrefugium during climatic instability

Montade V., Ledru M.P., Burte J., Passos Rodrigues Martins E.S., Verola C.F., Ribeiro da Costa I., Magalhães e Silva F.H.. 2014. Journal of Biogeography, 41 (6) : p. 1215-1226.

Aim The primary objectives of this study were (1) to assess, in the light of palaeoecological reconstruction, the climate stability hypothesis used by evolutionary biologists to explain high diversity in historically stable areas, and (2) to identify the response mechanisms of a tropical rain forest microrefugium to climatic variability. Location North-eastern Brazil, Serra de Maranguape. Methods Vegetation and climatic changes were reconstructed using a pollen record in a sediment core from a forest hollow, and the chronology was based on accelerator mass spectrometry radiocarbon analyses. Results Past vegetation dynamics consisted of three main forest types, shown by major compositional changes in rain forest assemblages between 5000 and 1000 cal. yr bp. Dense ombrophilous forest was abruptly replaced by heliophilous early successional tree taxa at 4275 cal. yr bp. These early successional tree taxa were established over a period of c. 100 years, and their dominance lasted for c. 750 years and was associated with dry conditions until 3525 cal. yr bp. Subsequently, the expansion of secondary successional tree taxa over a period of c. 550 years enabled the recovery of ombrophilous forest. Main conclusions The vegetation changes in the Serra de Maranguape provide evidence for the high sensitivity of this rain forest microrefugium to climatic variability on a multidecadal to millennial time-scale during the mid- to late Holocene. Despite the substantial compositional and climatic changes, this microrefugium apparently was continuously forested and responded to climatic instability by recruiting key species to its highly diverse stock. This evidence helps to address the joint concerns of evolutionary biologists and palaeoecologists regarding how forests can persist during periods of climatic variability by showing that some tropical regions can remain continuously forested despite reorganization during abrupt and short-term climatic changes. (Résumé d'auteur)

Mots-clés : biodiversité; taxonomie; lumière; composition botanique; couverture végétale; dynamique des populations; forêt; paléoclimatologie; changement climatique; forêt tropicale humide; brésil

Thématique : Foresterie - Considérations générales; Météorologie et climatologie; Ecologie végétale; Taxonomie végétale et phyto-géographie

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