DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 1-2/1972 str. 58 <-- 58 --> PDF |
Zaražena stabla izgubila su određenu količinu iglica. Navedenim se istraživanjima došlo do zaključka, da smanjenje asimilacijske površine prouzrokuje padanje debljinskog prirasta, koje smo za istraženi objekt mogli izraziti eksponencijalnom krivuljom na slici 6, gdje x = 1 označuje potpunu krošnju; x = 0.9 krošnju u kojoj nedostaje 10% iglica; x = 0.8 označuje krošnju koja je izgubila 20% iglica itd., a 0 označuje stablo bez ijedne iglice. Iz spomenute krivulje vidi se ovo: — ako je asimilacijska površina smanjena za 10% debljinski prirast pada za 20% — ako je asimilacijska površina smanjena za 20% debljinski prirast pada za 35% — ako je asimilacijska površina smanjena za 30% debljinski prirast pada za 45% — ako je asimilacijska površina smanjena za 40% debljinski prirast pada za 55% itd. itd. To je prvi rezultat istraživanja samo na jednom objektu. Istraživanja će se nastaviti na drugim objektima i u drugim uvjetima, da bi se mogla utvrditi zakonitost. Investigations of the effect of defoliators on the increment of Fir forests Withih the framework of complex investigations on »The epidemic dieback and drying of Silver Fir (Abies alba Mill.)« my role was among other things to investigate what repercussions the mentioned dieback had on the increment. Thanks to the financial funds of the Institute of Forest Research, Faculty of Forestry, Zagreb, it was possible for me to investigate the mentioned problem. Taking into consideration that already in previous years I was concerned with similar problems — either on my own initiative or as a collaborator of the Institute of Forest Research of the S. R. od Croatia — this paper represents in some measure a continuation of my previous studies. Therefore it is quite understandable that as the object of my research I chose the management unit of »Belevine« in the Gorski Kotar region (Croatia), i. e. the same acidophilus Fir forest (Abieto-BlechnetumHorvat) which has been the subject of repeated investigations, and was described in detail in Šumarski list (Forestry Review), Glasnik za šumske pokuse (Annals for Forest Research) etc. So far we have at our disposal very different and valuable data of measurements and observations regarding this faculty demonstration forest. As it was simultaneously subjected to various attacks, beginning with mistletoe (Viscum album f. sp. abietis Tub.) to the Fir needle moth (Argyresthia fundella F. R.), and other defoliators, I decided to focus my observations and measurements on this forest in order to give an answer to the query under discussion. The magnitude of increment is influenced by various factors. It is very difficult to isolate but one factor and to investigate its effect only. In the present investigations we have exactly to deal with such a case: it is neccessary 54 |