西北干旱地区表土孢粉与植被关系研究进展

较全面地综述了西北干旱地区表土孢粉与植被和气候关系的研究进展, 讨论了部分有指示意义的花粉,如云杉、杨、桦、禾本科、豆科等代表性花粉以及花粉浓度、A/C(蒿属Artemisia/藜科Chenopodiaceae)比值等问题.并提出了自己的一些见解和未来进一步开展工作的方向:如,在新疆某些地区很少发现桦属花粉可能属个别现象;可以根据藜科的生理习性解释草原区植被的A/C值较低即表明草原植被退化严重;进一步开展杨属(Populus)和桦属(Betula)花粉在林中的代表性、西北地区Ch(藜科Chenopodiaceae)/Po(禾本科Poaceae)值的研究,以及草原带与森林带之间的过渡地带的孢粉组合研究;今后需要将整个中国西北干旱区作为一个整体来研究,以深入了解孢粉-植被-气候的关系.

Progresses about the Studies on the Relationship between Topsoil Spore-pollen and Vegetation in Arid Areas of Northwest China

The progresses about the studies on the relationship of topsoil spore-pollen and vegetation and climate in arid areas of northwest China are summarized.The representation of some indication spores and pollens and other research issues are discussed.The main factors affecting the quantity of the Picea pollen are the distance to the Picea forests,altitude,air current,stream flow and climate.Some studies reveal that the Populus pollen can be preserved well.In some areas of Xinjiang,however,the Populus pollen and Betula pollen were rarely found due to the pollen themselves and the environment.The representative Gramineous pollen varies from different areas.The concentration of the representative Legumina pollen is low in the Altay region of Xinjiang because of the low pollen production perhaps.The factors affecting the pollen concentration in arid areas are moisture,soil pH value,oxidation or deoxidizing environment.The lower the A/C(Artemisia/Chenopodiaceae) value is,the drier the environment is.Moreover,the low A/C value can also reflect the slight disturbance of human activities in central Inner Mongolia.The correlation analysis was applied to research the spore-pollen assemblages in topsoil in northern slope of the Tianshan Mountains,the surface dust flux method was used for collecting pollen samples in topsoilin west Tibet.Some opinions about this topic and the future research direction are also discussed.The concentration of the representative Betula pollen is high in the temperate zone,Inner Mongolia and other places,it might be a exception that Betula pollen was rarely found in some areas of Xinjiang.The low A/C value of steppe vegetation indicates that the steppe vegetation is seriously degenerated.This can be explained by the physical habitat of Chenopodiaceae to absorb nitrogen and grow prosperously in the jamming area.Cy/Po(Cyperaceae/Poaceae) value is controlled by precipitation In Africa but by temperature in northwest Tibet.Referring to these two areas,some scholars can try to calculate the Cy/Po values in northwest China.It is deserved to research the pollen assemblages of woodland-steppe ecotone because it is seldom researched in this zone.The study on topsoil pollen in northwest China was carried out only in limited range.