2.4. Data analysis

The number of pollens of each taxon, the plant biological type and their anthropogenic status were built in a data base. The samples were characterized by the quantitative and qualitative analyses. The quantitative Melissopalynologic analysis determined the number of pollens, their average concentration per 10 g honey (P), and their relative percentage (P %). The qualitative Melissopalynologic analysis was performed using the presence-absence spectrum of the different pollen species to calculate their relative frequencies (F %) per sample, and per site [29,36]. A descriptive analysis, based on the number of pollens and their frequency, was first performed per apiary, plant biological type, plant anthropogenic status and the collection period. A multifactorial analysis of variance was also performed comparing the total pollen density per species, the relative pollen density and pollen frequency of the reference period (May 2012) to the one of May 2022 for assessing the decennial dynamic in pollen collection. The same analysis was performed for comparing the pollen content of each season in 2022 and this also helped determine the factors that best explained the decennial and seasonal dynamics in the relative frequency and pollen density.

The honey total pollen includes rare pollens. They represent less than 1 % of the pollen density in the considered periods or region and are exogenous pollens, brought to the hive by wind deposit at the hive entrance or atmospheric pollen that may be fixed to the pistils of the visited flowers [29,37]. Some plants species are also intrinsically poor pollen producing or are preferentially visited for nectar. These are “the frequent plants with rare pollen” which represent more than 1 % of the relative frequency (P%<1 and F% ≥ 1).

Targeting on the main pollen plant (P%≥1 %), the rare pollen plant (P%<1 %) and the frequent plant with rare pollen (P%<1 % and F%≥1 %), the pollinic status of the reference year and each season were characterized by the total pollen average density per 10 g of honey, the relative pollen density, and the relative pollen frequency as indicated in equations (1)–(3).