ABSTRACT In this study we analysed fossil Poaceae pollen of the Holocene from the Coastal Plain of Rio Grande do Sul (Águas Claras region), southern Brazil. Through light microscopy analysis, we measured the size of 60 pollen grains in the 28 samples (or, in samples with low frequency of Poaceae, sufficient pollen grains for the number of measurements to show a stability curve). The measurements of fossil Poaceae pollen were interpreted applying information from the modern Poaceae pollen dataset. Fossil Poaceae pollen showed changes from the Early Holocene to the present. Results showed that it is possible to obtain more ecological information (vegetation and climate changes) from fossil Poaceae pollen. Furthermore, dynamics of Poaceae vegetation during the Holocene are revealed. The palynological record documents the predominance of Poaceae herbaceous grasslands (63%) during the Early Holocene (10,974±49 14C BP) and the low representation of Poaceae arboreal forests (Bambuseae – 15%). Vegetation changes are detected from 3420years BP with an increase in Poaceae arboreal forests (75%) and a decrease in Poaceae herbaceous grasslands (115cm). This significant change may indicate the late vegetation shift in response to sea-level change. At 1072years BP, a peak of Poaceae arboreal forests (85%) indicates warm conditions. The representation of Poaceae arboreal forests (Bambuseae) decreased drastically (27%) at 536years BP. Pollen grains from samples closer to the surface (5 and 15cm) reflect modern vegetation in the region. Poaceae pollen is shown to be sensitive to climate changes and therefore useful for the analysis of dynamics of grassland and forest vegetation.

中文翻译：

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利用巴西南部沿海平原全新世沉积物中禾本科花粉粒获取草地草本 (Campos) 和森林树栖 (竹科) 生态系统动力学

摘要 在这项研究中，我们分析了巴西南部南里奥格兰德（Águas Claras 地区）沿海平原的全新世禾本科花粉化石。通过光学显微镜分析，我们测量了 28 个样品中 60 个花粉粒的大小（或者，在禾本科频率较低的样品中，测量数量足够的花粉粒以显示稳定性曲线）。应用现代禾本科花粉数据集的信息解释化石禾本科花粉的测量结果。禾本科花粉化石表现出从早全新世到现在的变化。结果表明，可以从禾本科花粉化石中获得更多的生态信息（植被和气候变化）。此外，揭示了全新世禾本科植物的动态。孢粉记录记录了早全新世 (10,974±49 14C BP) 期间禾本科草本草地 (63%) 的优势和禾本科树栖森林 (竹科 – 15%) 的低代表性。从 3420 年 BP 开始检测到植被变化，禾本科乔木林增加（75%），禾本科草本草地减少（115 厘米）。这种显着的变化可能表明植被因海平面变化而发生晚期变化。在 1072 年 BP，禾本科树栖森林的高峰（85%）表明气候温暖。禾本科树栖森林（竹科）的代表性在 536 年 BP 时急剧下降（27%）。靠近地表（5 和 15 厘米）的样本中的花粉粒反映了该地区的现代植被。