PL
Stanowisko cisa pospolitego Taxus baccata L. koło Mogilna jest aktualnie jednym z najbogatszych skupisk tego gatunku w polskiej części Karpat. Od kilkudziesięciu lat podlega ochronie rezerwatowej. W ciągu ostatnich 50 lat liczba osobników w populacji zwiększyła się prawie dwukrotnie, a sporo z nich wyrosło poza granicą rezerwatu. Badaniami objęto całość populacji, która liczy 1272 osobniki. Większość cisów nie wytwarza organów generatywnych (85%). W odniesieniu do danych sprzed 5 lat udział cisów o cechach pozwalających zidentyfikować płeć jest ponad czterokrotnie mniejszy, a w porównaniu do innych populacji karpackich badanych przez autorów - cisy w Mogilnie najsłabiej obradzają (15% populacji). Większość osobników posiada zdrową i żywotną koronę (89%), ale aż u 67% cisów stwierdzono różnego rodzaju uszkodzenia pnia, wśród których dominują porażenia grzybowe. Głównym problemem w rozwoju populacji jest słabe obradzanie osobników i brak odpowiednio licznego odnowienia, które zapewniałoby ciągłość rozwoju populacji.
EN
"Cisy w Mogilnie" is one of the nine nature reserves that protect European yew in the Polish Western Carpathians. The local yew population is one of the largest mountain populations of this species in Poland. Detailed studies of the population structure and health status of each specimen were carried out in 2011 and 2012. A total of 1 272 yew specimens (over 0.5 m high) occur on an area of ca. 36 ha, which means that the number of yews increased almost twice during the 50 years. Also seedlings and undergrowth of the protected species occurred in the reserve, but their spatial distribution was irregular. The yew specimens are distributed over the nature reserve area in clusters. The majority of them grow on gentle slopes exposed to the north, while others prefer steep slopes of the streams' banks (Fig. 2). In terms of altitude, their distribution in the reserve ranges from 556 m to 715 m above sea level. The height distribution of the local yew population specimens resembles, to some extent, the theoretical normal distribution, however, a discrepancy between the actual height distribution and the theoretical one is rather high (Fig. 7). The tallest yew in the nature reserve is 13 m high, while the female yew specimen growing outside the boundaries of the reserve is 19 m high (Fig. 9). The most numerous are 5.5-6.5 m yew specimens. Similarly to the height distribution, also the DBH distribution resembles the theoretical one. Also in this case, however, there are discrepancies between both patterns (Fig. 10). The DBH of yew specimens varies from 1.3 to 44.6 cm. The thickest specimen (nature monument) is growing outside the borders of the nature reserve - its stem circumference is 393 cm (Fig. 9). In the whole population, only seven specimens of varying size were found dead. The percentage of specimens with determined sex is very low (15%), including ca. 12% produced female flowers, and 3% - male flowers. The sex could not be determined for 85% of specimens, because they have not produced any flowers in the year when the study was carried out. It was found that as many as 89% of the yew population consist of specimens having vigorous, healthy crowns with deeply green needles and with no signs of any discolouration or defoliation (Fig. 12). On the other hand, the damaged stems were found in many yew specimens (67.4%; Fig. 13), which was caused mainly (35.5%) by various rot fungi. As far as the health status of the yew specimens is concerned, an interesting phenomenon was observed in the reserve, i.e. ca. 4.4% of stems had symptoms of bark peeling, and another 3.6% had traces of being grazed by red deer and roe-deer. Despite the fact that the European yew population protected in the nature reserve is large and still growing, its further maintenance is far from being secured. A low percentage of specimens producing flowers and poor seed production result in unsatisfactory natural regeneration of yew. Adverse growing conditions, such as a disturbed stand structure and strong competition from herbaceous vegetation dominated by blackberry (Rubus hirtus), reduce the establishment of seedlings and regeneration of yew specimens.