作 者 ：郄光发,杨颖,王成*,牟少华
期 刊 ：生态学报 2010年 30卷 15期 页码：3974~3982
Keywords:pollen concentration, diurnal variation, soft ground, hard ground,
摘 要 ：以油松（Pinus tabulaeformis）、白玉兰（Magnolia denudata）、白皮松（Pinus bungeana）、臭椿（Ailanthus altissima）为被试树种，对比研究了春季静风晴朗天气中软质与硬质两种地表条件下不同树种在距树10 m高度1.5 m处花粉浓度的日变化特征。研究结果表明：（1）4个树种在相同地表环境的花粉浓度日变化趋势基本一致，但同一树种花粉浓度的日变化特征在软、硬两种地表条件下的差异明显。软质地面一天内空气中花粉浓度最大值出现14:00时前后，04:00时花粉浓度最低，这与全天内空气温度的变化正好一致，而与空气相对湿度的变化恰好相反。硬质地表近地空间空气中的花粉浓度则呈现“双峰型”日变化特征，两次峰值分别出现在14:00时和20:00时，硬质地面花粉浓度20:00时晚高峰的出现时间与硬质地面温度日峰值一致。（2）分析硬质地表20:00时花粉浓度高峰出现的原因可能与硬质地面的散热特性有关，硬质地面夜间释放积蓄热量的过程会在一定程度上增强近地面空气的对流运动，并辅助空气中的花粉粒子不断飘散，形成花粉浓度晚高峰。（3）相对于软质地面来讲，硬质地表对空气中花粉飘散的影响作用持续时间更长，这也在一定程度上延长了致敏花粉的危害时间，加剧了致敏花粉的污染程度。研究还进一步在花粉致敏树种栽植、地表覆盖方式等方面进行了讨论；同时建议花粉症患者根据花粉污染发生规律合理规避花粉浓度聚集高峰期出行，从而有效缓解致敏花粉对易感人群的健康威胁。
Abstract:Influence of land surfaces on the pollen dispersal under urban environment is rarely investigated. We measured pollen concentration dispersed from four commonly used urban tree species (Pinus tabulaeformis, Magnolia denudata, Pinus bungeana and Ailanthus altissima) on two spring windless sunny days in 2006 in Beijing. The pollen concentration and microclimate measurements were conducted in the locations 10m away from the sampling trees at 1.5m above the ground. Our objectives were to contrast the impact of grass covered (Soft) and paved (Hard) surfaces on the diurnal variations of pollen disposal. Our research indicated that: (1) Diurnal variations of pollen dispersal among four species had similar tendency in same urban surface condition. But the same tree species showed distinctive diurnal variations under different surface conditions (soft and hard). Under soft ground, diurnal variation of tree pollen had one peak presented at 14:00pm while the lowest pollen concentration was at 04:00am. That was positively correlated with air temperature but had negative correlations with relative humidity. The diurnal patterns of tree pollen showed clear variation with high peaks at around 14:00pm and 20:00pm and low values around 04:00am and 18:00pm under hard ground. And the peak of pollen concentration appeared at 20:00pm was consistent with the peak of ground temperature in hard ground. Overall, the pollen concentration during the day was significantly higher than at night while the pollen concentration under hard ground was significantly higher than under soft ground during the night. (2) Peak pollen concentration at 20:00pm under hard ground could be attributable to the thermal dynamics of the ground. Heat strapped by hard ground during the daytime was released at night, causing the convection movement of air near the ground and promoting tree pollen release into the atmosphere. Consequently, the pollen concentration peak happened at night. (3) Pollen dispersal during the daytime was not significantly affected by different surface conditions. However, the surface impacts on the pollen dispersal were observed during the night. Comparing with soft ground, hard ground showed greater and longer influence on pollen dispersing in the air. That made the pollen concentration remained at high concentration level for several hours in the near ground air after the sunset. This phenomenon will lead to the extended time of allergenic pollen dispersal and aggravated pollen pollution. Therefore, urban forest tree species selection and urban surface mulching were recommended to avoid possible pollen pollution for urban dwellers, and most importantly for those pollen allergy-pro citizens. In addition, we recommended that the hay fever patients should avoid their outdoor activities and sports during the time when the pollen concentration is high. This would lead to lower the risks of allergenic pollen threats to their health.
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