Prognozowanie wystąpień faz fenologicznych pierwiosnki omączonej Primula farinosa L. (Primulaceae) – krytycznie zagrożonego gatunku - w odniesieniu do fenologii innych składników lokalnej flory i panujących warunków termicznych
Authors:   University of Agriculture in Krakow, Gajewski Zbigniew 
Published: November 2021

In Poland, the bird’s-eye primrose (P. farinosa) is a rare and critically endangered species. Currently, it occurs only in one location in the area of the Jaworki village in Radziejowa Range (of Beskid Sądecki mountains). This is the last of the nine previously existing locations, and the only one occurring in the mountains. To maintain the species, as well as the moutain fen on which it grows, a multiannual conservation program has been implemented, including, among other measures, conducting environmental monitoring and performing active protection procedures. In 2012–2014, studies were carried out, aiming to identify the phenology of P. farinosa in its natural location amid other elements of local flora, and to elaborate reasonably accurate forecast methods of its phenological phases, in relation to the performed procedures. One of the methods was based on comparing subsequent phenological phases of P. farinosa, mainly the dates of flowering and opening of the fruits, with the dates of flowering of other species that commonly occur in the vicinity. On the basis of temperature data from the IMGW meteorological station in Krościenko nad Dunajcem, available via the Internet, an attempt to forecast the phenophases of P. farinosa has also been made, based on the developed network of nearby meteorological stations. A degree-days method was used. Prior to that, a value of base temperature (Tb) characteristic for P. farinosa was assessed, as necessary for further calculations, and the values of SAT (Sum of Active Temperatures, using the formula for GDD values) have been determined for the dates of occurrence of subsequent phenological phases of P. farinosa. These parameters were calculated using temperature data recorded at the location. During the observations, it was established that the dates of flowering for P. farinosa were dependent on the air temperatures during spring. The flowering period of the population in Jaworki took place in the months of April through to June, and it did not exceed 7.5 weeks. P. farinosa is one of the earliest blooming species in that location. Other species, also flourishing during the blooming thereof, included Eriophorum angustifolium, Caltha laeta, Chrysosplenium alternifolium, Oxalis acetosella, and Primula elatior. The full bloom of P. farinosa lasted for about 2 weeks, and it took place between the end of April and the end of the second decade of May. During its full bloom, in that same location, Cardamine pratensis, Geum rivale, and Valeriana simplicifolia also flourished. Trees and bushes from the rose (Rosaceae) family proved to be especially useful in the forecasting of P. farinosa flowering period. During the flowering of P. farinosa, in lower locations, species from the Prunus and Cerasus genera subsequently flourished, followed by the Malus, Sorbus, and Crataegus genera. The opening of P. farinosa fruits was observed in the last days of June or at the beginning of July. The date of commencement and duration of this phase is probably subject also to the degree of air humidity. Although in this period numerous species flourish such as Ononis arvensis, Valeriana sambucifolia, Cichorium intybus, Melilotus alba, Achillea millefolium, Daucus carota, Geranium pratense, and Agrimonia eupatoria, the forecasts based on those are not accurate. When forecasting this phase, as well as the majority of other phases, the SAT value calculation based on the degree-days method works well. The Tb base temperature (threshold temperature) for P. farinosa from Jaworki, determined for its calculation, is 0.75°C. However, for the calculation purposes, the rounded value of Tb = 1.0°C can also be used. When adopting the value of Tb = 0.75°C for calculations, the full bloom of P. farinosa falls within the period in which the SAT values remain between 310°C and 469°C, the optimum (culmination) of the full bloom occurs at about 408°C, and the beginning of capsules opening and release of P. farinosa seeds occur when the SAT values reach 1049°C. For Tb = 1.0°C the full bloom falls within the period in which the SAT values are between 295°C and 449°C, the optimum of full bloom occurs at 390°C, and the capsules begin opening at 1018°C. When using this method, the differences between the forecasted and the observed dates of P. farinose blooming were between –4 and +3 days, and the beginning of opening of its fruits, between –1 and 0 days. In case of no temperature data available from the given location, the forecasting can be also performed based on the data from the IMGW meteorological station in Krościenko. The accuracy of calculations is increased through the implementation of appropriate temperature data adjustments, resulting from the difference of location and height. The temperatures in Jaworki are 2°C lower compared to the station in Krościenko. The dates determined in this way are less accurate than those determined directly at the location, and they differ from the actual dates: in case of full bloom, the difference is in the range of –6 to +2 days, and in case of the beginning of capsules’ opening, it is –2 to –1 days. Probably, it is also possible to implement forecasting based on the data from new automated meteorological stations situated closer to the location, but this can be done only after the adjustment appropriate for every station has been determined and implemented. As demonstrated, the elaborated forecasting methods of P. farinosa phenological phases at the location in Jaworki (Beskid Sądecki) are sufficiently accurate and they may be used in the future as a tool supporting the implementation of measures related to active protection of the species.