104 KURT HOLZER 



P. cembra that are 50 years old, but only a few cm in height (Figala, 

 1927; Oswald, 1963), especially in stands above timberline. Here climate 

 is very severe; but P. cembra is very resistant to such high-elevation 

 climatic conditions (Holzer, 1959; Tranquillini , 1956, 1958). Under these 

 severe timberline conditions medium height at age 50 is about 1.5 to 2.5 m 

 for P. oerrbra in closed stands (Gregori, 1887). It is much greater (about 

 6 to 15 m) for P. peuce , because the yearly growth of this species is 

 about 30 to 50 cm (Fig. 2, MUller, 1928; Nedjalkov, 1963). This best 

 height growth of P. peuce is found at an age of 20 to 40 years (MUller, 

 1928; Nedjalkov, 1963). So we find much better growth in P. peuce than 

 in P. cembra, because the best shoot growth of P. oembra is about 20 to 

 25 cm. Even though P. peuoe is supposed to be a fast growing white pine, 

 the very slow early growth of this species gives difficulties - especially 

 at nursery stage. 



Both species are resistant to frost throughout the year, especially 

 to late frost (MUller, 1928); only winter coldness and temperatures fluc- 

 tuating around the freezing point of the needles may injure the leaves 

 (Holzer, 1958, 1959; Tranquillini, 1964; Tranquillini and Holzer, 1958). 



ADULT GROOTH POTENTIAL 



As shown in Figure 3 the height growth potential of European white 

 pines is not very high, when compared with other native species like Norway 

 spruce or Scots pine. The height growth begins very late but lasts for a 

 very long time. Both species are adapted to cold mountainous climates 

 with long winters and short summers. The slow growth appears to be under 

 genetic control - it cannot be accelerated by planting into warmer 

 climates. The longer vegetation period (growing season) at lower sites 

 does not accelerate growth through secondary, or lammas-shoot growth 

 (Holzer, in press) . Adaptability to zones colder than the source locality 

 is possible only with restriction of growth potential; in fact P. cembra 

 is able to grow at an average temperature of 0°C per year (Fuschlberger, 

 1928; Tranquillini, 1957, 1964). 



The best height growth is found in P. sibirica. Here we have seven 

 classes of height growth potential (Fig. 3, after Leskov and Semeckin, 

 1963); the best individuals attain heights up to 40 m after 300 years, but 

 at an age of 100 years the best heights are only 25 m. P. peuce in 

 the Balkan Mountains reaches a height of 26 m at an age of 160 years 

 (Nedjalkov, 1963). Most comparisons with Piaea abies or Pinus sylvestris 

 L. in natural stands show that these latter species are growing faster, 

 but not in the best region of the white pines (Hengst, 1967; Nedjalkov 

 and Krastanov, 1962; Schikov, 1965). The height growth of P. peuoe on 

 the best sites is about the same as that attained by P. sibirica on 

 site class III (Fig. 3). The alpine P. cembra shows the poorest height 

 growth of all (Figala, 1927); on its best sites (Class I-III) it only 

 reaches heights equivalent to those of P. sibirica on its 3 poorest sites 

 (Classes IV-Va) . The best, selected trees of P. cembra in Austria, how- 

 ever, are on the average, one site class better (Holzer, 1969). They 

 reach about 26 m at an age of 150 years. Here also the comparison with 

 alpine Picea abies (Fig? 3) shows that the growth of P. cembra is not 

 good at optimal climatic conditions. 



It is the same way with diameter growth and wood production; we can 

 see the slow growth of all these white pine species. However, diameter 

 growth is much better than height growth in all three species. Most 



