The study aim was to analyze and interpret long-term trends in temperature and olive reproductive features, including full flowering dates and daily pollen concentrations, in central Italy. A 40-year database (1982–2022) of pollen and temperature records was utilized. Temperature changes significantly affect spring phenology and olive trees, sensitive to climate change, exhibit earlier flowering in response to higher spring temperatures. Although this adaptation may lower pollen levels, benefiting public health, it could negatively impact agricultural yields. Olive trees in the study area demonstrated phenological plasticity, transitioning from rigid to flexible flowering behaviors. They adjusted the Growing Degree Days (GDDs) required for flowering once they reached a threshold of maximum advancement. Until 2004, the trees accumulated similar GDD values. With rising temperatures, earlier flowering occurred at fixed GDD values of 650 and 750. Subsequently, the trees began accumulating higher GDD values, stabilizing the flowering date and preventing further advances. This phenological plasticity allows olive trees to adapt their life cycle and developmental stages to environmental changes such as temperature, light, and water availability. This flexibility helps them survive in changing conditions and prevents excessively early flowering. By avoiding flower opening and pollen release during periods of unstable weather (such as late spring rainfall and strong winds), the trees enhance pollen transport and successful pollination.

中文翻译：

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意大利中部橄榄开花和气候关系的长期分析


该研究的目的是分析和解释意大利中部温度和橄榄繁殖特征的长期趋势，包括完整的开花日期和每日花粉浓度。利用了 40 年（1982-2022 年）的花粉和温度记录数据库。温度变化显着影响春季物候，对气候变化敏感的橄榄树会因春季温度升高而提前开花。尽管这种适应可能会降低花粉水平，有益于公众健康，但它可能会对农业产量产生负面影响。研究区的橄榄树表现出物候可塑性，从刚性开花行为过渡到柔性开花行为。一旦达到最大进展的阈值，他们就调整了开花所需的生长期数天数 （GDD）。直到 2004 年，这些树积累了相似的 GDD 值。随着温度的升高，在 650 和 750 的固定 GDD 值下开花较早。随后，树木开始积累更高的 GDD 值，稳定了开花日期并防止了进一步的进步。这种物候可塑性使橄榄树能够根据环境变化（如温度、光线和水的可用性）调整其生命周期和发育阶段。这种灵活性有助于它们在不断变化的条件下生存，并防止过度提前开花。通过避免在不稳定天气期间（如春末降雨和强风）开花和花粉释放，树木增强了花粉运输和成功授粉。