Airborne pollen assemblages and their relationships with climate factors in the central Shaanxi Province of the Loess Plateau:a case in Xiaheimugou,Luochuan County
The research of airborne pollen is one of important contents of modern palynology, vegetation changes and prediction. The airborne pollen analysis results in the Luochuan County Shaanxi Province from 2007 to 2009 shows that airborne pollen assemblages are mainly consistent with the distribution characteristics of regional vegetation and their parent plant florescence. The total fluxes and Artemisia fluxes were obviously increased, and woody plant pollen fluxes are significantly reduced in 2008-2009 than in 2007-2008. That should be closely related with the precipitation decreasing. In 2007-2008, the annual rainfall precipitation is higher than 500 mm; correspondingly, the tree pollen percentage is higher than 30% , showing the characteristics of forest vegetation. In 2008-2009, the annual rainfall is less than 450 mm, herbaceous pollen percentages are more than 80% and the tree pollen percentage is less than 10% , more indicating the characteristics of steppe vegetation, however, no obviously vegetation changes can be directly observed, suggesting that pollen assemblages can be more sensitively to the change of climate than the vegetation. The correlation analysis between major pollen taxa fluxes and climate factors shows that climatic factors can influence the pollen assemblages and fluxes. Pinus, Quercus, Rosaceae pollen fluxes are mainly related with the temperature in spring, and pollen fluxes increase with the increase of temperature; In the other seasons, these three pollen fluxes are mainly influenced by the relative humidity, and the pollen fluxes reduce with the increase of humidity. Ulmus pollen fluxes are mainly influnced by the temperature in winter, and the higher the temperature is, the larger of the fluxes are. Populus fluxes are only controlled by the spring temperature, with the increase of spring temperature, the pollen fluxes are decreased. Elaeagnaceae fluxes are mainly affected by the relative humidity and wind speed in spring, and when the relative humidity is lower and the wind speed is higher, the pollen fluxes become higher. Most of the herbaceous pollen fluxes are mainly affected by the relative humidity and wind speed in spring and winter, the lower relative humidity and the higher wind speed are benefit to the increase of herbaceous pollen fluxes. In addition, Poaceae pollen fluxes are also affected by the spring temperature, and the pollen fluxes rise with the increase of temperature. Compositae fluxes are also affected by temperature, humidity and wind speed in summer and autumn, when the lower temperature and humidity, and higher wind speed are benefit to the increase of pollen fluxes. All of the results indicate that the airborne pollen assemblages in the central region of loess plateau, can reflect the regional vegetation composition, and are very sensitive to the climate changes, and suggesting airborne pollen assemblages have very important role in understanding and predicting the local climate change, vegetation dynamic and so on.
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NSTL
万方数据
维普
