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Navadna ameriška duglazija je zaradi nazadovanja smreke in svojih izjemnih dimenzij ter lastnosti že dolgo kandidat za vnos v naše gozdove. V diplomskem delu smo preučili, kakšna sta zgradba in negovanost sestojev z navadno ameriško duglazijo in kako se ta naravno pomlajuje. Meritve smo opravili v petih sestojih v gozdnogospodarskem območju Kranj. V sestojih smo postavili ploskev z duglazijo in kontrolno ploskev ter opravili polno premerbo, izmerili višine in ocenili kakovost. Na ploskvi z duglazijo smo postavili še ploskvice za analizo mladja. Povprečni premer duglazij se je gibal od 50,8 do 70,9 cm, v višino so merile od 33,9 do 45,2 metra, njihov volumen je znašal od 3,3 do 7,8 m3. Povprečni premer izbrancev je bil 76,0 cm, višina je merila 44,3 metra, volumen je meril 7,0 m3. Sproščenost izbrancev je bila primerljiva z drugimi vrstami, njihov delež krošnje je bil večinoma več kot 50 % dolžine debla. Gostota mladja duglazije je bila 6933 osebkov na ha. Večina mladja so bile klice oziroma velikosti do 20 cm. Delež objedenosti je bil 19,1 %. Duglazija bi bila primerna za manjše vnose v gozdove in dodatni prihodek iz gozda. K temu nakazujejo velike dimenzije in kakovost dreves. Douglas fir has long been a candidate for introduction into our forests due to decline of Norway spruce and its dimensions and properties. In this thesis we analyzed structure and tending of stands with Douglas fir and how it naturally regenerates. Measurements were carried out in five stands in Forest Management Region Kranj. A Douglas-fir plot and a control plot were set up in stands, and a full calipering, height measurements and quality assessment were carried out. In the Douglas-fir plot, we also set up plots for the natural regeneration analysis. The average diameter of the Douglas fir trees ranged from 50,8 to 70,9 cm, and from 33,9 to 45,2 m their height and their volume measured 3,3 to 7.8 m3. The average diameter of the crop trees was 76,0 cm, their average height vas 44,3 meters and average volume was 7,0 m3. Growing space of the crop trees was comparable to other tree species and their crown proportion was in most cases more than 50 % of the trunk length. Density of Douglas fir regeneration was 6933 individuals per ha. Most of the young trees were one-year-old seedlings or up to 20 cm in height. Proportion of browsed individuals was 19,1 %. Douglas fir would be suitable for small-scale introduction and additional income from forests. This is indicated by the large size and quality of the logs. |
