Environmental changes on grass flowering phenological trends (2000–2021)

Abstract

Societal Impact Statement

Climate change is impacting the flowering of grasses, which in turn impacts the health of people due to allergic reactions triggered by grass pollen. The timing of flowering was studied for 15 grass species across various habitats in the Cordoba region of Spain. This analysis revealed that the grass flowering season is lengthening, as early-flowering grasses are blooming even earlier in spring and the blooming of late-flowering grasses is delayed. This work highlights the impact of climate variations on the lifecycle and environmental responses of grasses and the consequences of this for human health and wellbeing. Summary

Phenology examines recurring biological events in organisms and their relationship with climate. The Poaceae family's phenology is crucial due to its pollen production, the main cause of European pollinosis, affecting 35% of the population. This study, conducted around Córdoba city (Spain) from 2000 to 2021, analyzed the reproductive phenology of 15 spring-blooming grass species across different land covers (pasture, shrub, riverbanks) and altitudes to identify climate change indicators. The study observed various phenological stages, including pre-flowering, flowering, and fruiting. Results suggest that increasing winter and spring temperatures, along with decreasing March rainfall, are extending the pollen season. Early-flowering species are blooming sooner, while late-flowering species are delayed, leading to prolonged pollen exposure for allergy sufferers. Key species indicating climate change include Bromus, whose phenology shifts with water availability; Hordeum muralis, which responds to temperature changes based on altitude; and Dactylis glomerata, which is flowering significantly earlier despite its perennial life cycle. These findings highlight the impact of climate variations on grass phenology and their consequences for human health.