Grzegorz Iszkuło, Anna Katarzyna Jasińska, Karolina Sobierajska
Dendroecological differences between Taxus baccata males and females in comparison with monoecious Abies alba
Dendrobiology 2011, vol. 65: 55-61
Abstract: Taxus baccata L. is a rare and endangered dioecious species in Europe. Species of this mating system are considered to be the most vulnerable to extinction. It is believed that one reason for this state may be the uneven reproductive effort and different habitat requirements of the two sexes. Silver fir and European yew have very similar ecological requirements, but fir is a monoecious species. The aim of this study was to compare the growth rate and the effect of precipitation and temperature on the annual tree-ring width of silver fir and both sexes of European yew. The study site was the Knyazhdvir reserve in western Ukraine, located near the limit of the geographical range of both species. Knyazhdvir reserve is the site of one of the last yew populations in Europe with a large number of individuals (about 15,000 individuals above 1.3 m height) growing alongside fir. Wood samples were taken from 15 male and15 female specimens of T. baccata and from 15 specimens of A. alba and were subjected to a standard dendrochronological procedure. The results showed high positive correlation between the temperatures in February and March and the tree-ring width in the studied species and genders. The response of annual tree-ring width to the examined climatic factors was relatively similar in yew and fir. However slight differences were found between males and females of T. baccata. The growth rate decreased more rapidly in females compared to males, probably following sexual maturation. Precipitation in April had a positive effect on firs and female yews, but not on male yews. This confirms earlier reports of the requirement of female specimens of dioecious species for a higher humidity than male individuals.
Additional key words: reproductive effort, dendrochronology, European yew, silver fir