陕西中部黄土高原地区空气花粉组成及其与气候因子的关系——以洛川县下黑木沟村为例

空气花粉研究是现代孢粉学、植被变迁与预测的重要内容之一.陕西省黄土高原地区洛川县2007-2009连续2a的空气花粉分析表明:空气花粉组成与区域植被分布特征和植物花期一致.与2007—2008年相比,2008-2009年的花粉总通量及蒿属花粉通量明显增加,但木本植物花粉通量降低,这主要与2008-2009年降水明显偏少密切相关.2007-2008年降雨量高于500 mm,花粉组合中乔木花粉百分比高于30％,表现出森林植被特点；2008-2009年降雨量少于450 mm,花粉组合中草本花粉高于80％,乔木花粉低于10％,更多表现出草原植被特点.但从植被观测来看并没有明显的变化,表明花粉组合较植被对气候变化更为敏感.主要花粉类型与气候因子的相关分析表明:气候因子影响空气花粉的组成及数量.栎属、松属、蔷薇科花粉数量主要受春季温度影响,温度越高花粉数量越多；其他季节花粉数量主要受相对湿度影响,湿度越低,花粉数量越大.榆属花粉数量主要与冬季温度有关,温度越高,花粉数量越高.杨属只受春季温度影响,春季温度越低,花粉数量越多.胡颓子科花粉含量主要受春季相对湿度、风速影响,相对湿度越低,风速越大,花粉数量越多.绝大多数草本花粉数量均主要受春、冬季相对湿度及风速影响,相对湿度越低,风速越大,花粉数量越高；此外,禾本科花粉数量还受春季温度影响,温度越高,花粉数量越多；菊科花粉数量在夏秋季节还受温度、湿度和风速的共同影响,温度越低,湿度越低,风速越大,花粉数量越多.这些结果表明,黄土高原中部地区的空气花粉特征能反映区域植被组成,且对气候变化非常敏感,对认识和预测当地气候变化与植被动态等具有重要意义.

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.