Abstract
<title>Abstract</title> <p> Airborne pollen is increasingly recognized as a valuable tool for assessing plant biodiversity in mountain ecosystems where traditional field surveys are logistically challenging. In Alpine bioregions, pollen data can provide critical insights into vegetation dynamics, climate change impacts, and conservation priorities. However, the relationship between modern airborne pollen and local plant biodiversity remains understudied in high-altitude ecosystems. This study investigates the pollen–plant biodiversity relationship across four protected high-altitude sites in Trentino (2022–2024). Airborne pollen was sampled using Sigma-2 passive traps, while plant biodiversity was quantified via multi-scale vegetation surveys (10 m, 100 m, and 1000 m radius). Data were analyzed using Jaccard similarity indices, non-metric multidimensional scaling (NMDS), and Pollen-Vegetation ratios (R-values) across separate plant growth forms. A total of 53 pollen taxa and 306 plant species (corresponding to 38 pollen-equivalent plant taxa) were identified across the sites. Herbaceous pollen richness selectively captured fine-scale local plant diversity of open alpine habitats; woody pollen reflected broader, landscape-level downslope forest belts. Anemophilous arboreal taxa (e.g., <italic>Alnus</italic> , <italic>Pinus</italic> ) yielded high R-values (pollen-to-vegetation abundance ratios > 1), while entomophilous herbs scored significantly lower. High-resolution aerobiological data demonstrated a 2-week lag in Poaceae flowering between 1900 and 2600 m a.s.l. Airborne pollen data obtained via gravitational deposition offer a cost-effective, scalable, and non-invasive approach to complement traditional field-based plant biodiversity metrics. Integrating modern aerobiological data with multi-scale vegetation data provides a reliable environmental baseline for tracking climate-driven changes, such as in plant phenology and biodiversity in vulnerable mountain ecosystems. </p>