Interaction between stem damage, crown vitality and growth performance of European yew in Central–East Europe

As long-lived, slow-growing tree species, European yew (Taxus baccata L.) has considerable potential for dendrochronological use. The increasing probability of decline and the worsening of yew health status endanger the species diversity of temperate forests. In 2015–2017, we sampled adult yew populations with scattered occurrence in limestone beech forests (Fagetum dealpinum), in which yew trees exhibit the top growth performance. Altogether, 150 trees were sampled (294 cores) at four localities. By using the general linear model, we investigated the interactions between stem and crown status, sex and growth performance of yew trees. Based on the previous results and innovative measures of competition and canopy closure, we explored the promotion of silviculture care for female over the male trees and formulated exact release cutting rules. The results demonstrate divergent growth trends between male and female trees and the pronounced negative effects of crown and stem damage on growth performance of European yew. Expected decreases in radial growth of damaged female trees in comparison with male ones is less confirmed. Despite this, making silvicultural treatments for females as a priority is recommendable. Our findings can improve the effectiveness of forest management and restoration activities in European temperate forests, where yew adults are threatened by the higher degree of shading and herbivory pressure.

Deer game, a key factor affecting population of European yew in beech forests of the Veľká Fatra Mts, Slovakia

Browsing and bark peeling by ungulates is known to affect biodiversity and may constitute the main driving factor of single tree population dynamics. In Slovakia, European yew (Taxus baccata L.) is a threatened species protected by law and present in many protected areas. In the study, we emphasize that protecting land and individual plants may not be sufficient for maintaining of yew populations, unless controlling over damage by deer game is also undertaken. Our results show that in beech forests of the Veľká Fatra Mts, browsing and bark peeling constitute the main negative factor affecting yew seedling-sapling ingrowth transition, and the mortality and vitality loss of adult yew trees. We argue that ungulates may have a larger effect on biodiversity conservation than currently realized.