Population structure and health conditions of European yew in 'Cisy nad Liswarta' reserve

Abstract

The aim of the study was to recognise the structure (sex, height, diameter) and vitality of European yew (Taxus baccata L.) population in the ‘Cisy nad Liswartą' reserve (50°46'27,12"N 18°47'11,86"E). The field investigations were performed in years 2005−2009. We measured diameter at breast height, diameter at root collar and height of all yews in the reserve. Sex of the individuals was determined as well as their health condition was classified into one of five classes. Total number of life and dead yew specimens (with height over 0,5 m) accounted to 466. Majority of the population grew in dense stands (stand density index 0.5−0.7). Sex was described for 55% of the population. Number of female individuals was 142 (30%) and male 116 (25%). Lack of or small crown transparency was found for 30% of life yew trees. The share of high transparency crowns equalled 11%. Damage caused by the game (especially deer) was older than 10 years and found for 42% life trees. Seedlings occurred under the canopy of 47 mature trees (10% of population). 15 relevés were established in the investigated stands. Natural regeneration of yew was found on 11 of them. 5 characterised with small number of yew seedlings. The greatest number of seedlings equalled 200 individuals. It was found that the number of yews higher than 0.5 m decreased in comparison to the previous surveys. Female and male yew trees occurred in the reserve, so the generative breeding is possible. Health condition of the analysed yew population is moderate. Problems with survival of the seedlings was observed. The special treatments should be recommended – cutting of some competitors to give more light for natural regeneration and fencing the greater number of yew seedlings