Pollen and climate change: is the signal more evident in the natural enviroment? A case study in the Alps (province of Trento, northern Italy)

Climate change affects physiology, phenology and distribution of plants. Several authors report an advance in spring phenomena in relation to climate change. Airborne pollen are considered good proxy to describe the phenological phases of flowering. Referring to phenological events, an early pollen release has been observed, in addition to an increasing trend in quantities. Usually, aerobiological monitoring stations are located in urban context with high antropogenic disturbance: in fact, in addition to climate change, such areas are subjected to the presence of air pollutants and changes in land use. Aim of this study is to verify if the climate change effects on pollen season are more clearly detectable in a natural remote situation than in an antropized one. To achieve this goal pollen data collected by an aerobiological monitoring station located in an Alpine ecosistem (Paneveggio Pale di San Martino natural park, Trentino, north Italy, 1020 m a.s.l.) were considered, and compared to those obtained by the other station present in the same region, located in the valley bottom in a rural/urban context (San Michele a/A, 228 m a.s.l.). The pollen sampling was performed using two Hirst-type samplers, according to the UNI CEN/TS 16868 protocol. Data of 10 arboreal and herbaceous pollen taxa collected between 2006 and 2016 were considered. The dataset was checked and validated. The pollen seasons have been defined using 10 different descriptors; non-parametric statistic was used to evidence the influence of meteorological parameters. First results show an early start of the pollen seasons expecially for the arboreal taxa. In this study area, where water availability is not a limiting factor, the meteorological parameters related to air temperature seem the most relevant in influencing the pollen seasons. The monitoring of airborne pollen in natural remote areas with low anthropogenic disturbance is helpful in detecting the effect of climate change on pollen season