内蒙古中部四子王旗荒漠草原过渡带表土花粉分析

POLLEN ANALYSIS OF SURFACE SAMPLES FROM THE DESERT-STEPPE TRANSITIONAL AREA OF SIZIWANGQI,CENTRAL INNER MONGOLIA

通过研究内蒙古中部四子王旗地区的表土花粉,试图揭示荒漠草原地区小尺度范围中表土花粉的植被和气候指示意义。源自4个不同植物群落的19块表土花粉显示:研究区表土花粉组合主要以草本植物蒿属(Artemi-sia)、藜科(Chenopodiaceae)花粉占优势,两者百分含量一般在60 %以上;禾本科(Poaceae)花粉具低代表性,平均含量在5 %左右;另含有一定数量的白刺属( Nitraria)、麻黄属( Ephedra)、菊科( Asteraceae)和葱属(Allium)等花粉为特征。笔者首次提出的(蒿属+禾本科+菊科)/(白刺属+麻黄属+藜科)百分比值,有效地揭示了研究区北部较南部要干旱,与A/C比值及当地现生植被生境和气候因子相吻合。研究结果对我国内陆干旱、半干旱荒漠草原区第四纪古植被的恢复,以及古气候的重建提供了参照依据。

A total of 19 surface samples were palynologically analyzed in attempt to reveal the implication of surface pollen data under the modern vegetation and climate conditions in the desert-steppe area in Siziwangqi, Central Inner Mongolia, NE China. The results show that the pollen flora is characterized by the dominant Artemisia and Chenopodiaceae, usually accounting for above 60%. Poaceous pollen is at low level with an average percentage about 5% and some typical desert-steppe taxa are common such as Nitraria, Ephedra, Asteraceae and Allium. Exotic are limited arboreal pollen such as Pinus, Betula,and Quercus induced by winds from the southern mountainous areas. The pollen flora is much similar to those from the arid and semi-arid area in NE China but is significantly different from the modern Stipa-Salsola dominant plant communities where the surface soil was sampled. This may can be mainly attributed to the high productivity and dispersal of Artemisia and Chenopodiaceae in windy arid-semiarid areas, which overshadows the representation of the Poaceae-dominated steppe. The ratio of （Artemisia＋Poaceae＋Asteraceae）/（Nitraria＋Ephedra＋Chenopodiaceae） [（A＋P＋A）/（N＋E＋C）] in pollen percentage proposed by the authors is useful to significantly identify the climatic condition in terms of relative aridity which is comparable to the ratio of Artemisia/ Chenopodiaceae （A/C）. The result shows that the northern part （Zone A-1） with lower （A＋P＋A） / （N＋E＋C） and A/C is drier than the southern part （Zone A-2） corresponding to the modern precipitation distribution in the study area.