Coelho Luciane G, Barth Ortrud M, Araujo Dorothy S Dde
Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis, Rio de Janeiro, Brazil.
An Acad Bras Cienc. 2008 Sep;80(3):531-41. doi: 10.1590/s0001-37652008000300013.
The Poço das Antas National Biological Reserve is located in Rio de Janeiro State, southeast Brazil. This paper presents information on past environmental characteristics of the area through pollen analysis. Two sedimentary columns were collected and five samples were selected for radiocarbon dating. The following ages of the columns from bottom to top were detected: column 1 - 1.20-1.16 m: 6080 +/-40 years BP, 0.775-0.735 m: 4090 +/-40 years BP, 0.385-0.345 m: 1880 +/-80 years BP; column 2 - 1.22-1.18 m: 3520 +/-40 years BP, 0.23-0.19 m: 1810 +/-40 years BP. Three samples from column 1 and two samples from column 2 were selected for pollen analysis: 1.20 m, 0.77 m and 0.37 m of column 1 and 1.22 m and 0.21 m of column 2. Chemical treatment followed standard methodology. The palynological analysis shows that around 6080 years BP the study area was dominated by a rain forest and from around 4090 years BP the vegetation changed to a fragmented forest, restricted to low hills and surrounded by an open area of grassland and pioneer plants, swamps and peat areas. The pollen assemblage of the samples 3520, 1880 and 1810 years BP suggest the permanence of this kind of vegetation between 4000 years BP and the actual.
波索达斯安塔斯国家生物保护区位于巴西东南部的里约热内卢州。本文通过花粉分析展示了该地区过去的环境特征信息。采集了两根沉积柱，并选取了五个样本进行放射性碳测年。从下到上检测到的柱样年龄如下：柱样1 - 1.20 - 1.16米：距今6080±40年，0.775 - 0.735米：距今4090±40年，0.385 - 0.345米：距今1880±80年；柱样2 - 1.22 - 1.18米：距今3520±40年，0.23 - 0.19米：距今1810±40年。从柱样1中选取了三个样本，从柱样2中选取了两个样本进行花粉分析：柱样1的1.20米、0.77米和0.37米处，以及柱样2的1.22米和0.21米处。化学处理遵循标准方法。孢粉学分析表明，在距今约6080年时，研究区域以雨林为主，从距今约4090年起，植被转变为碎片化森林，局限于低山，周围是草地和先锋植物的开阔区域、沼泽和泥炭地。距今3520年、1880年和1810年样本的花粉组合表明，这种植被在距今4000年至现在之间一直存在。
