通过对广东湛江湖光岩玛珥湖B孔顶部8～0.6m岩芯较高分辨率的孢粉分析,揭示了该区全新世植被、气候变化的历史:早全新世(约11600～7800cal a BP),木本植物花粉含量为56.0%,其中热带木本植物花粉含量占优势,最多的时期发生在9500～8000cal a BP左右,达到木本植物花粉的60.2%,反映气候热暖潮湿;中全新世(7800～4200cal a BP),热带-亚热带植物花粉含量明显下降,而草本植物和山地针叶植物花粉含量增加,指示了中全新世温度下降;晚全新世4200cal a BP开始,草本植物和山地针叶植物花粉明显增多,揭示出晚全新世湖光岩地区温度、湿度明显下降.研究结果表明,中国南方热带-亚热带地区高温湿润的全新世适宜期发生在早全新世(9500～8000 cal a BP),与全球低纬地区全新世气候变化格局一致.初步认为,全新世早期,在岁差周期的控制下,北半球较强的太阳辐射驱动了热带辐合带(ITCZ)和副热带锋面季风降水带同时向北推移,造成中国热带低纬度地区早全新世最适宜期.湖光岩地区中晚全新世气候干旱趋势和气候波动除了与北半球夏季太阳辐射强度减弱有关外,可能与该时期ENSO的活跃也有一定的联系.
205 surface pollen samples from different communities in Northern China were analyzed to understand the quantitative relationship between pollen and its original vegetation. Pollen analysis and vegetation investigation show that the pollen assemblages differ a lot in different vegetation regions. Arboreal pollen account for more than 30% in temperate broad-deciduous forests region. In temperate steppe regions, herb pollen percentages are more than 90%, where Artemisia and Chenopodiaceae are domi- nant pollen types with Artemisia percentages more than 30%. In temperate desert, Chenopodiaceae pollen percentages are more than Artemisia, where ferns are rare. Cyperaceae pollen percentages are more than 20% in sub-alpine or cold meadows. The relations between pollen percentages and vegeta- tion cover indicate that most arboreal pollen shows a close relationship with parent plant covers, most shrubby pollen types have more or less correlations, but most herbs do not show clear correlations. For arboreal pollen types, Picea pollen shows the closest correlation with spruce trees coverage, then is Quercus and Carpinus. Betula, Larix and Juglans have also high correlation coefficients with their plants coverage, but Betula pollen is of overrepresented pollen type and more than 40% in birch forest, while Larix and Juglans pollen is underrepresented and pollen percentages are more than 10% in Larix or Juglans pure forests. Pinus is of overrepresented pollen type, and pollen percentages have some relations with plants cover. Pine forest might present when Pinus pollen percentages are more than 30%. The relations between Ulmus and Populus pollen percentages and vegetation cover are not close, where they are mixed with other arbors, they cannot be recorded easily, but if their pollen percentages are more than 1%, Ulmus or Populus trees should exist. For shrubby pollen types, the correlation be- tween Vitex pollen percentages and vegetation cover is the highest, then is Corylus, Tamariaceae and Nitraria, and their pollen percent
