%0 Journal Article
%T Preliminary palynological analysis of a Holocene peat bog from Apakar¨¢-tepui (Chimant¨¢ Massif, Venezuelan Guayana)
%A Rull
%A V.
%A Montoya
%A E.
%A Nogu¨¦
%A S.
%A Huber
%A O.
%J Collectanea Botanica
%D 2011
%I Consejo Superior de Investigaciones Cient¨ªficas
%X Preliminary palynological analysis of a Holocene peat bog from Apakar¨¢-tepui (Chimant¨¢ Massif, Venezuelan Guayana).- This paper reports the preliminary palynological results, at a millennial scale, of a Holocene peat bog sequence, since around 8.0 cal kyr BP to the present, obtained in the summit of the Apakar¨¢-tepui (2170 m elevation), in the Chimant¨¢ massif, located in the neotropical Venezuelan Guayana. The early Holocene was characterized by a vegetation different to the present, in which trees and shrubs dominated and Myrica (Myricaceae) was the main element of the gallery forests around a permanent water body, as indicated by the continuous presence of Iso tes (Iso taceae) in high percentages. Around the middle Holocene (5.3 cal kyr BP), a shift towards more herbaceous and non-flooded communities occurred, and the present day vegetation established. This has been interpreted as a shift from warmer and wetter climates to cooler and drier conditions. The first phase, from 8.0 to 5.3 cal kyr BP, falls within a warming phase widely documented worldwide, known as the Holocene Thermal Maximum. The millennial trends shown here will be refined with further studies at centennial to decadal time scales. These results support the hypothesis that the best sites to detect paleoenvironmental changes in the summits of the tabular Guayana mountains are close to altitudinal ecotones. An¨¢lisis palinol¨®gico preliminar de una turbera holocena del Apakar¨¢-tepui (Macizo de Chimant¨¢, Guayana venezolana).- Este art¨ªculo presenta los resultados palinol¨®gicos preliminares, a escala de milenios, de una secuencia holocena, desde 8.0 cal kyr BP hasta la actualidad, obtenida en la cima del Apakar¨¢-tepui (2170 m de altitud), en el Macizo del Chimant¨¢, situado en la regi¨®n neotropical de la Guayana venezolana. El Holoceno temprano se caracteriz¨® por una vegetaci¨®n diferente a la actual, dominada por ¨¢rboles y arbustos, en la que Myrica L. (Myricaceae) era el elemento principal de los bosques de ribera que circundaban un cuerpo de agua permanente, como indica la presencia cont¨ªnua de Iso tes L. (Iso taceae). Durante el Holoceno medio (5.3 cal kyr BP), se produjo un cambio a una vegetaci¨®n m¨¢s herb¨¢cea, estableci¨¦ndose las comunidades que actualmente ocupan el ¨¢rea. ¨¦sto se interpreta como indicativo de un cambio desde climas m¨¢s c¨¢lidos y h¨²medos a condiciones m¨¢s fr¨ªas y secas. La primera fase, de 8.0 a 5.3 cal kyr BP, coincide con una fase clim¨¢tica c¨¢lida ampliamente documentada a nivel global, conocida como el M¨¢ximo T¨¦rmico del Holoceno. Las tendencias milenarias obtenidas e
%K Neotropics
%K Paleoclimatology
%K Paleoecology
%K Palynology
%K Quaternary
%K Cuaternario
%K Neotr¨®pico
%K Paleoclimatolog¨ªa
%K Paleoecolog¨ªa
%K Palinolog¨ªa
%U http://collectaneabotanica.revistas.csic.es/index.php/collectaneabotanica/article/view/187/189