DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 1-2/1966 str. 95 <-- 95 --> PDF |
This will give rectangular plots 4,20 X 8,40 m = 35,28 m2 for pine and square plots 6 X 6 m = 36 m2 for spruce. With the 8 replicates planned each provenance will cover 282,24 m2 and 288,0 m2 for a pine and spruce plantation respectively. Thus on a site of 5 ha it will be possible to include about 170 provenances. Smaller number of provenances will require a relatively smaller area. In Table 1 the number of trees per plot at different ages is given for pine and spruce. The number of trees per ha. at different ages shown in Table 1 were taken from Schwappach´s yield tables (1943) for the best site class. On poorer sites there will be more trees per ha. Table 1 Number of trees per hectare and per plot at different ages for pine and spruce Age, years Pin e per ha. 1.20 X 0.60 m. per plot 35.22 sq. m. Spruc e per ha. 1 X 1 m. per plot 36: 1 14,000 49 10,000 36 25 4,380 15.5 5,110 18.4 30 2,880 10.0 3,702 13.3 35 2,080 7.3 2,800 10.0 40 1,570 5.5 2,210 7.9 5(1 998 3.5 1,468 r>.´i 60 739 2.6 1.037 3.7 70 583 2.1 771 2.8 80 480 1.7 598 2.2 90 403 1.4 479 1.7 100 342 1.2 396 1.4 120 265 0.9 284 1.0 The values per plot have been calculated from Schwappach´s figures corrected for the actual plot size. If the site quality is lower than class I, then there will be more trees per plot at a given age. As can be seen from Table 1, the proposed arrangement will give about 8 trees per plot at 1/3 of the rotation age assuming a rotation of 100 years for pine and 120 years for spruce. Thus, as has been discussed above, there will be enough trees to evaluate the productivity per unit area. At the end of the rotation there will still be one tree per plot and, with the 8 replicates, 8 trees of the same provenance in the whole experimental area. This will be sufficient to compare the provenances in respect of tree quality and of numerous other features. Productivity per ha will of course no longer be estimable. However, it will be possible to corroborate all other characters with those tested earlier, and to establish juvenile-mature correlations. For the reconstruction of the population by means of a seed orchard, 40 trees are deemed necessary. These will be available at the age of 40 years in pine (from all the 8 replicates), and at the age of 50 years for spruce. At these ages both the productivity per hectare and most of the other qualities of interest will have been reliably compared for the provenances in the experiment and the best ones would have been selected. |