## 4 Discussion
In the case of trees, 63.8% of the analyses resulted in significant positive correlations with temperature [39], which coincides with the results obtained from daily data within the MPP by the present study, where both _Olea_ and _Populus_ obtained significant positive correlations, while the opposite was true for Cupressaceae, with significant negative correlations with this meteorological variable. At the same time, 41% of the tree analyses found a positive correlation between precipitation and MPP onset date, with increases in precipitation leading to a later onset of the pollen season. And higher precipitation correlated with lower average daily tree pollen concentrations in 67.5% of the analyses [39]. This coincides with the present study, as it was verified, from the results obtained with daily data within the _Populus_ MPP, the only type of pollen for which significant correlations with precipitation were obtained, that the higher the precipitation, the lower the concentration of this pollen. Alterations in pollen seasonality vary according to the taxon studied and the geographical location. In the United Kingdom, from 1995 to 2020, an association was detected between the increase in temperature and an earlier onset of the pollen season of _Quercus_, as well as with a peak day of pollen concentration in the atmosphere of Poaceae [40]. In southern Spain, for several tree taxa with winter pollination and with the meteorological variables of temperature and precipitation, in the period 1994-2017, it was found that flowering was delayed, especially in the case of taxa with flowering closer to spring (_Populus_ and _Ulmus_) [40]. At the same time, _Platauns_, which generally begins its pollination period somewhat later than _Populus_ and _Ulmus_, may have a different start to flowering in two cities such as Badajoz and Malaga, the former with a markedly continental climate and the latter a coastal city with mild winters and warm summers, but both with the same Mediterranean macro-bioclimate. In fact, in Malaga, there is a very clear delay in the onset of flowering, due in turn to a delay in the cold requirement accumulated during the winter that is needed before flowering occurs [41]. Likewise, the _taxa_ with an earlier flowering of those studied [40] (Cupressaceae, _Almus_, and _Frazinus_) are more influenced by temperature and precipitation before flowering, while these parameters have more influence on the _taxa_ with a later flowering during the pollen season. This is seen in this study, according to the results obtained from monthly data; however _Populus_, _Ulmus_, and Cupressaceae _taxa_, contrary to the previous study, show negative correlations with temperature, and only the positive correlation with precipitation coincides in _Populus_[40]. The study conducted in the city of Granada, which also used a rank correlation analysis and coincided in some of the selected pollen types with those of this study, states that the meteorological variables that most influence, in general, the concentration of pollen of these types are maximum daily temperature, relative humidity, global radiation, and insolation, although with different effects on the different types of pollen. Specifically, those most correlated with pollen types in that study were daily mean relative humidity, precipitation, daily minimum temperature, and vapor pressure [12]. In the NW of the Iberian Peninsula, between 1993 and 2000 [42], a significant and positive correlation of pollen release and dispersion of _Pinus_, _Platanus_ and _Quercus_ with temperature and insolation was found, as well as a negative correlation with precipitation. In the case of the present study, temperature and insolation were obtained, followed by radiation and relative humidity, in all 4 cases in all their sub-variables.