DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 1-2/1972 str. 59     <-- 59 -->        PDF

to find out what repercussion had the dieback of Fir stands on their
increment.


Considering that in the last mass attack chiefly defoliators took part,
I thought it would be best to establish first how much the assimilating´
surface of attacked Fir stands was reduced. To this purpose I described
a special working method, which was published in »šumarski list« No 7/8,
1970 under the title of »How to determine the percentage decraase of
assimilation area in infested Silver Fir Forests?«. According to this method
I found out the percentage of reduction of assimilating surface in the whole
management unit of »Belevine« in the month of May, 1969. I take the data
about this from the mentioned number of šumarski list.


Reduced assimilating
Forest district Compartment No. Area ha surface in %


VII, 1 a 11,3 6
VII, 1 b 21,5 7
VII, 1 c 19,7 5
VII, 1 d 23,2 10
VII, 1 e 8,7 5
VII, 1 f 18,4 7
VII, 2 a 22,4 7
VII, 2 b 25,0 7
VII, 2 c 22,1 8
VII, 3 a 17,6 7
VII, 3 b 18,6 6
VII, 3 c 18,1 7
VII, 4 a 12,7 13
VII, 4 b 21,0 7
VII, 4 c 11,2 8
Total : 271,15


If the areas of individual compartments are taken as weights, we obtain
the average percentage of reduction of the assimilating surface for the
management unit of »Belevine«. It amounts to about 7%.


Two years later, i. e. at the beginning of July, 1971, I applied the same
working method and established the percentage of reduction of the assimilating
surface to be 9%. This figure was computed on the basis of measurements,
which consisted in that in the management unit of»Belevine« were
laid out 13.550 km of sample-strips 10 m. wide making a total of 13.55 ha.
sample-strips, or about 5% of the total area of the management unit (271.15
ha.). On these strips were measured the breast height diameters (d. b. h.) of
all trees above the minimum measurement limit of 10 cm. In addition to
this there were observed by means of a field-glass the crowns of each
measured tree and was estimated the loss of needles in percents from 0 to
100, where 0 means a healthy Fir tree and 100 a dead one without needles;
10% means that there were destroyed 10% of needles, or that the actual
assimilating surface amounts to 0.9 in relation to the full crown, 20% means