Impact of adjacent trees to mensurational characteristics of yew

In December 2015 the next part of the research population yew (Taxus baccata) took place in NPR Chlumská stráň. The specimens exceeding 4 meters at height at which the sex is possible to determine were selected from the total population. And from this group 50 individuals were randomly selected and the following characteristics were measured height, breast-height diameter, girth, height deployment of the first green branches, distances ends of the branches from the trunk, a distance of 5 nearest trees, their height and azimuth, also was intended sexes and crown shape. Volume and height of the crown were calculated. The aim is to determine how the surrounding tree species affect mensurational characteristics of the yew not only basic characteristics such as thickness at breast height and tree height, crown but also the crown characteristics and health status. The average diameter of the examined yews is 41,53 cm and a height of 13,66 m. The yew crowns were investigated in detail. The most important and interesting data are the yew crown projection and distances of competing species. The average crown projection yew is 79,25 square meters, the average height of the crown is 12,26 m, the surface of the crown is 2531,46 square meters, the average crown width is 10,36 m and the average volume of 429,80 cubic meters. 95 % of all surveyed yew has asymmetric crown, making it likely the high impact of competitive species. The most abundand species of competitors is hornbeam (Carpinus betulus) with a total of 60 individuals, an average height of 13,6 meters and an average distance of 5,79 meters, followed by lime(Tilia cordata) and manna ash (Fraxinus ornus). Crown yew are deflected to the north, northwest and west direction because of terrain conditions and competing trees. Research in the future should be also focused to the marginal tree species and for yew it should be very appropriate to establish permanent sample plots and to use collected information for return of yew to our forests