DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu
| ŠUMARSKI LIST 1-2/1966 str. 86 <-- 86 --> PDF |
selected. This work is being done already for several years by the Institute of Dendrology and Körnik Arboretum of the Polish Academy of Science. So far 1144 trees have been selected, and they are presented in Table 2 according to species within our major forest administrative units. ;: A fm«.*« 3Ađ % ^» ´* ´´ ´ -./´ ´ >l --1 pi * " ** ´ ´ X N { l * . i Fig. 2. Distribution of pine seed stands presented cumulatively for each climatic-forest region. Presently plus trees are being sought in these parts of the country which have little been searched to-date. In this work there is much cooperation between the Institute of Dendrology and the employees of the Forest Administration, who report prospective plus trees on small »survey cards« that are being verified later by members of the Institute of Dendrology staff. Accepted trees are then placed on an official plus tree registry, whereupon such trees become protected against felling. In the choice of plus trees, on the basis of phenotypic characters orriginally Swedisch criteria were employed, however these had to be modified later, particularly as regards the demands for crown form. At present the largest number of selected trees are Pinus silvestris (337 trees), concentrated mainly in the north-eastern part of Poland, on the Mazurskie Lake District and in the 84 |