01612nas a2200193   4500008004100000245005900041210005800100300001200158490000800170520100900178653002801187653001801215653001301233653002101246653001501267653001501282100001801297856010301315       2001                        eng d00aLate Holocene rainforest disturbance in French Guiana.0 aLate Holocene rainforest disturbance in French Guiana  a161-1760 v1153 aPalm swamp forest sediments collected in French Guiana provide new data about late Holocene rainforest. Two cores were collected in 'Les Nouragues' ecological station (4 degrees 05'N, 52 degrees 40'W). The lithology shows two different types of sediment, organic peat in the upper part and oxidized clay with low organic content and lacking pollen in the lower part, both separated by a gravel horizon. Radiocarbon dates show that this gravel horizon could have been deposited between 4500 and 3000yrBP. Pollen analysis carried out on the organic sediments record rainforest disturbances between ca 1520-1380 and 1060-860cal yrBP suggested by the presence of the pioneer tree species Cecropia together with other shade intolerant genera. Cecropia is recorded for a period that lasts between 660 and 320 years. This abnormal duration for presence of a pioneer species in rainforest is explained by brief and repeated changes in the composition of the canopy asssociated to perturbations of the palm swamp.10acanopy gap regeneration10aFrench Guiana10aholocene10apaleoenvironment10apalynology10arainforest1 aLedru, M, -P.  uhttps://insectafgseag.myspecies.info/en/content/late-holocene-rainforest-disturbance-french-guiana