Temporal Variation of Airborne Cupressaceae, Pinus, and Quercus Pollen and Their Relationship with Environmental Variables in Three Sites of Mexico City

Climatic factors influence plant physiology and distribution, thereby affecting pollen production and its aerobiological processes. We analyzed the relationship between the reproductive phenology of Cupressaceae, Pinus sp., and Quercus sp. Airborne pollen was sampled using a Hirst-type volumetric spore trap at three locations: Coyoacán, Cuajimalpa, and Desierto de los Leones. For the three pollen types, the main pollination period (MPP), seasonal variation, and peak pollen emission dates were determined. The relationship between meteorological parameters and the MPP was assessed using Spearman’s correlation test, while the Kruskal–Wallis test (Dunn’s post hoc) was applied to compare pollen types and sampling sites. Wind trajectory and pollen grain deposition were analyzed using the HYSPLIT model. The pollination period of the Cupressaceae family began in July–August and ended in February. Pinus sp. started between August and December and concluded between May and July, whereas Quercus sp. began between February and March and ended between May and June. Spearman’s analysis revealed positive correlations with temperature and solar radiation, and negative correlations with precipitation and relative humidity. The number of pollination days for Cupressaceae and Pinus sp. was similar between Coyoacán and Cuajimalpa, but differed significantly from Desierto de los Leones. In contrast, Quercus sp. showed no significant differences among the three sampling areas. The HYSPLIT model indicated that wind currents at different altitudes originated from varying directions, highlighting potential emission sources of the different pollen types. Cupressaceae pollen was present in the atmosphere throughout the year, whereas Pinus and Quercus pollen exhibited interannual and seasonal fluctuations due to their biennial periodicity and the flowering patterns of different species.