Phenological description of Ailanthus altissima (Mill.) Swingle using the BBCH-scale: Groundwork for developing strategies to control invasive species and mitigate potential allergy risks

Abstract

Alien species pose a growing threat to biodiversity and ecosystems due to their capacity to establish and proliferate beyond their native ranges. Among them, Ailanthus altissima (Mill.) Swingle ranks among the most concerning species globally, especially across the Mediterranean basin, where its spread continues to intensify. Native to China and northern Vietnam, this tree has been widely introduced for ornamental purposes. Its invasive success facilitates the displacement of native flora, disruption of ecological processes, and significant impacts on public health due to its allergenic potential, including in urban areas. This study applies the BBCH-scale to describe the full phenological cycle of a population in Cuenca (Spain). A total of 20 adult individuals were monitored (10 males and 10 females) leading to identify 8 of the 10 main BBCH-scale stages and 41 secondary stages, covering the entire cycle from bud emergence to leaf senescence, while linear interpolation was used for the temporal analysis of stage duration. Additionally, statistical comparisons between sexes were conducted using one-way ANOVA with post-hoc Tukey HSD test, while Pearson’s correlation analysis assessed to correlate these patterns with meteorological conditions, highlighting the influence of key meteorological variables (temperature, relative humidity, insolation and precipitation) on phenophase timing. These findings demonstrate that the BBCH-scale offers a precise framework to monitor phenology in this species, supporting improved management of invasive populations and enabling better forecasting of pollen release, crucial for public health monitoring in areas with high allergy incidence.